Anticipation in familial pancreatic cancer

Philipps University of Marburg, Marburg, Hesse, Germany
Gut (Impact Factor: 14.66). 03/2006; 55(2):252-8. DOI: 10.1136/gut.2005.065045
Source: PubMed
ABSTRACT
Previous studies of anticipation in familial pancreatic cancer have been small and subject to ascertainment bias. Our aim was to determine evidence for anticipation in a large number of European families.
A total of 1223 individuals at risk from 106 families (264 affected individuals) were investigated. Generation G3 was defined as the latest generation that included any individual aged over 39 years; preceding generations were then defined as G2 and G1.
With 80 affected child-parent pairs, the children died a median (interquartile range) of 10 (7, 14) years earlier. The median (interquartile range) age of death from pancreatic cancer was 70 (59, 77), 64 (57, 69), and 49 (44, 56) years for G1, G2, and G3, respectively. These indications of anticipation could be the result of bias. Truncation of Kaplan-Meier analysis to a 60 year period to correct for follow up time bias and a matched test statistic indicated significant anticipation (p=0.002 and p<0.001). To minimise bias further, an iterative analysis to predict cancer numbers was developed. No single risk category could be applied that accurately predicted cancer cases in every generation. Using three risk categories (low with no pancreatic cancer in earlier generations, high with a single earlier generation, and very high where two preceding generations were affected), incidence was estimated without significant error. Anticipation was independent of smoking.
This study provides the first strong evidence for anticipation in familial pancreatic cancer and must be considered in genetic counselling and the commencement of secondary screening for pancreatic cancer.

Full-text

Available from: John P Neoptolemos, Jan 07, 2015
PANCREAS
Anticipation in familial pancreatic cancer
C D McFaul, W Greenhalf, J Earl, N Howes, J P Neoptolemos, for the European
Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer (EUROPAC),
R Kress, M Sina-Frey, H Rieder, S Hahn, D K Bartsch, for the German National Case
Collection for Familial Pancreatic Cancer (FaPaCa)
...............................................................................................................................
See end of article for
authors’ affiliations
.......................
Correspondence to:
Dr W Greenhalf,
Department of Surgery,
5th Floor UCD Building,
Daulby St, Liverpool L69
3GA, UK; greenhaf@
liverpool.ac.uk
Revised version received
2 May 2005
Accepted for publication
9 June 2005
Published online first
21 June 2005
.......................
Gut 2006;55:252–258. doi: 10.1136/gut.2005.065045
Background: Previous studies of anticipation in familial pancreatic cancer have been small and subject to
ascertainment bias. Our aim was to determine evidence for anticipation in a large number of European
families.
Patients and methods: A total of 1223 individuals at risk from 106 families (264 affected individuals) were
investigated. Generation G3 was defined as the latest generation that included any individual aged over
39 years; preceding generations were then defined as G2 and G1.
Results: With 80 affected child-parent pairs, the children died a median (interquartile range) of 10 (7,
14) years earlier. The median (interquartile range) age of death from pancreatic cancer was 70 (59, 77),
64 (57, 69), and 49 (44, 56) years for G1, G2, and G3, respectively. These indications of anticipation
could be the result of bias. Truncation of Kaplan-Meier analysis to a 60 year period to correct for follow up
time bias and a matched test statistic indicated significant anticipation (p = 0.002 and p,0.001). To
minimise bias further, an iterative analysis to predict cancer numbers was developed. No single risk
category could be applied that accurately predicted cancer cases in every generation. Using three risk
categories (low with no pancreatic cancer in earlier generations, high with a single earlier generation, and
very high where two preceding generations were affected), incidence was estimated without significant
error. Anticipation was independent of smoking.
Conclusion: This study provides the first strong evidence for anticipation in familial pancreatic cancer and
must be considered in genetic counselling and the commencement of secondary screening for pancreatic
cancer.
A
pproximately 5% of pancreatic cancers are inherited,
1–4
in some instances associated with a general familial
cancer syndrome such as familial atypical multiple
mole melanoma syndrome, familial adenomatous polyposis,
hereditary non-polyposis colorectal cancer, hereditary breast-
ovarian cancer syndrome, and Peutz-Jeghers syndrome.
5–9
Familial pancreatic cancer is a rare syndrome with an
apparent autosomal dominant pattern of inheritance,
although the main gene or genes responsible have not yet
been identified.
2310
Germline BRCA2 mutations may occur in
up to 20% of familial pancreatic cancer families
311
and the
chromosomal locus 4q32-34 has been associated with one
family.
12
Genetic anticipation refers to the earlier age of onset of
familial diseases in successive generations. Anticipation was
originally identified in some inherited neurological dis-
eases
13 14
and then in certain diseases with a non-mendelian
pattern of inheritance.
15–19
Anticipation is well established in
familial leukaemias
20–22
and lymphomas
23–25
and may also
occur in solid tumours.
26
It is important to determine if
anticipation is seen in familial pancreatic cancer because this
will provide clues as to the nature of the disease gene and
facilitate prediction of the age of cancer onset for an
individual. This will assist in estimating whether an
unaffected individual is a carrier, which is vital for linkage
analysis, and will be important for determining the most
appropriate age at which to commence secondary screening
for pancreatic cancer.
27 28
Evidence for anticipation in familial pancreatic cancer has
not been adequately tested.
29 30
One of the difficulties with
assessing genetic anticipation is ascertainment bias.
31 32
With
late onset diseases, particularly where the disease gene is
unknown, a retrospective study will show apparent anticipa-
tion because individuals in later generations who may go on
to develop the disease relatively late will appear to be
unaffected.
15 33
These kinds of data are also hierarchical in
structure due to the nesting of affected patients within
families and hence are not completely independent.
31 34
Ascertainment bias may be reduced by increasing the number
of families studied and by applying relatively new statistical
methodology to minimise biases.
31 34–36
This study of 106
European families has employed standard analytical techni-
ques as well as adopting a novel iterative approach to
minimise biases in the analysis of anticipation.
MATERIALS AND METHODS
Subjects
Subjects were recruited by the European Registry of
Hereditary Pancreatitis and Familial Pancreatic Cancer
(EUROPAC)
34
and the German National Case Collection for
Familial Pancreas Cancer (FaPaCa).
29
Following informed
consent the probands completed family and personal health
questionnaires. Patients’ clinicians also completed parallel
questionnaires which were used for confirmation of clinical
details, and hospital and pathology notes were also obtained.
Clinics were arranged and family members were invited to
attend via the proband.
Individuals were classified as affected based on histological
confirmation of pancreatic ductal adenocarcinoma where
Abbreviations: EUROPAC, European Registry of Hereditary
Pancreatitis and Familial Pancreatic Cancer; FaPaCa, German National
Case Collection for Familial Pancreas Cancer; G1, generation 1; G2,
generation 2; G3, generation 3
252
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available. Where histology was not available good quality
medical notes or reliable cancer registry information were
used, in all cases copies of reports or notes were considered by
at least two members of the study (for EUROPAC CDM or NH
and WG). Familial pancreatic cancer was defined as families
with two or more affected individuals not fulfilling criteria
for any other familial cancer syndrome. Previously described
familial pancreatic cancer families with a germline BRCA2
mutation identified were excluded from this analysis in order
to reduce genetic heterogeneity.
11
Too few cases of pancreatic
cancer are available in these BRCA2 families or families from
other cancer syndromes for meaningful subgroup analysis.
Statistical analyses
Age was expressed as median (interquartile range).
Improvement in diagnosis could give the impression of
anticipation if event time was taken as age of diagnosis while
improvements in treatment would reduce apparent anticipa-
tion if event time was taken as age of death; to be
conservative in our evaluation of anticipation, event time
was taken as age of death from pancreatic cancer. Affected
parent-affected child pairs were analysed with the paired t
test. Individuals were assigned to one of three generations
(G1, G2, and G3) depending on their position within the
family tree and the matched version of the anticipation test
described by Hsu et al employed.
35
G3 was the latest
generation that included any individual at significant risk
of cancer (defined as any individual aged over 39 years) and
preceding generations were then defined as G2 and G1.
Earlier and later generations were not classified (fig 1). For
comparison, affected individuals were also compared by three
year of birth cohorts (1900–1919, 1920–1939 and 1940–69);
individuals were excluded from this analysis where the
precise date of birth was unknown despite the age having
been stated. Survival from birth until death from pancreatic
cancer was analysed by the Kaplan-Meier method and
compared by log rank analysis. Survival analysis was also
undertaken by truncation to an equal 60 year observation
period for all individuals to correct for follow up time bias.
36
All at risk individuals were included from the families, with
data censored at present age or age of death from causes
other than pancreatic cancer. Because all of the aforemen-
tioned methods have an inherent bias, a novel iterative
approach was also developed. This involved multiplication of
the chance an individual is a carrier of the disease gene by an
age related measure of penetrance and establishing that this
would only reflect the observed incidence of cancer assuming
that the age related penetrance increases with successive
generations; this will be described in more detail later. To test
the influence of smoking, individuals were divided into those
who had ever smoked (ex- and present smokers) and those
who had never smoked. Smoking data were analysed using
survival analysis as well as the x
2
and Fisher’s exact
probability tests. The statistical package used was StatView
Version 5 and significance was set at p,0.05.
Ethics
The study was approved by the North West Multicentre
Research Ethics Committee (UK); MREC 03/8/069. Local
research ethics committees approval was obtained in
participating centres.
RESULTS
Description of families
At the time of guillotine, 106 families had been recruited with
multiple cases of pancreatic cancer, no BRCA2 mutation, and
a family tree that was complete over the range of individuals
to be analysed (not necessarily including siblings of the
earliest individuals in each kindred). Of these families, 88
had only pancreatic cancer, 10 had pancreatic (at least two
cases within the family) and gastric cancers (there were 21
cases of gastric cancer in total), and the remaining eight
families had pancreatic cancer (at least two cases) in
association with other malignancies. In 52 families histol-
ogical confirmation of pancreatic cancers was possible in at
least one case; in the remainder good quality medical notes or
reliable cancer registry information was used. A typical
family tree is shown in fig 1.
Description of affected individuals
There were a total of 1223 individuals at risk and 264
individuals with pancreatic cancer. Pancreatic resection is
only normally undertaken in 2.6–9% of patients as a result of
a high incidence of locally advanced and metastatic disease at
presentation.
37–40
Despite this, histological confirmation was
possible in 57 (22%) affected individuals; good quality
medical notes or reliable cancer registry information was
Affected Off kindred
64
89
3464
70
24424536
5711
46
62
8468
G1
G2
G3
Figure 1 A typical familial pancreatic cancer family tree. This is a family with eight affected individuals, showing their ages at death or last contact.
The generations within the family were defined on the basis that generation 3 (G3) was the first generation with any individual aged over 39 years and
G2 and G1 were defined from this.
Table 1 Differences in age of death of paired affected
parents and affected children
Affected child-affected
parent pairing
No of
pairs
Difference in age of death
(mean (95% CI)) p Value*
All child-parent pairings 80 210.7 (213.9, 27.6) ,0.001
Son-father 21 24(29.4, 1.4) 0.21
Son-mother 18 217.7 (223.4, 212.0) ,0.001
Daughter-father 18 28.4 (216.7, 20.2) 0.06
Daughter-mother 23 213.4 (218.1, 28.6) ,0.001
*Paired t test.
There were 80 pairs consisting of a parent and child who have died of
pancreatic cancer. The differences in age of death are given with 95%
confidence interval (95% CI). Children died at an earlier age than their
parents, this was statistically significant but may be explained by bias.
Thus more stringent testing of anticipation was applied.
Anticipation in pancreatic cancer 253
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used for all others. At least two affected individuals in each
family were first degree relatives.
Other diseases
We observed 22 cases of diabetes; 16 cases in as yet
unaffected and six in affected individuals. There were 10
cases of acute pancreatitis (three in patients who later
developed pancreatic cancer) and two cases of chronic
pancreatitis in as yet unaffected individuals. In addition to
cases of pancreatic ductal adenocarcinoma and gastric cancer
there were three basal cell carcinomas, two brain tumours,
four cervical cancers, 11 colorectal cancers, one duodenal
cancer, two cholangiocarcinomas, one pancreatic acinar cell
carcinoma, one pancreatic neuroendocrine tumour, and 17
cancers with unknown primary. Although it is possible that
the other cancers and pancreatic diseases are surrogate
markers for gene carriers, the numbers are too small to make
any definitive conclusions, and for the purposes of anticipa-
tion analysis, these individuals were considered to be
unaffected.
Smoking
In 84 families where smoking data were available, analysis
did not reveal a statistically significant difference between
smoking habit in affected and non-affected individuals
(Fisher’s exact test p = 0.44). Neither did we establish that
smoking affected survival using a Kaplan-Meier analysis (log
rank x
2
1
= 0.44, p = 0.5; n = 125 smokers and 79 non-
smokers). Smoking is discussed later in relation to anticipa-
tion.
Standard analyses for anticipation
Median (interquartile range) age of death from pancreatic
cancer was 62 (53, 70) years and was lower than expected.
41
Median age was 65 (57, 71) years for 138 women compared
with 59 (49, 67) years for 126 men, but this sex difference
was not significant by survival analysis (log rank x
2
1
= 2.6,
p = 0.27). Children died a median of 10 years earlier than
their parents among the 80 child-parent affected pairs
identified (p,0.001, paired t test) (table 1). Later generations
had an earlier age of death from pancreatic cancer than
individuals from preceding generations and a similar effect
was observed in the analysis of birth cohorts (both p,0.001)
(table 2). There was a degree of correspondence between the
birth cohorts and generations and so some of the effect may
be because of genuine differences between generations
(fig 2).
Kaplan-Meier analysis showed that cumulative deaths
from pancreatic cancer for all at risk individuals by 77 years
was 50%; as only 50% of the kindred would be predicted to
carry the gene, this implies 100% lifetime risk for gene
carriers. As cumulative survival actually falls below 50%
beyond 77 years, there must be an element of ascertainment
bias in this analysis, which becomes apparent as the number
of at risk individuals declines; but in support of autosomal
dominance, and high penetrance, 25% cumulative incidence
of pancreatic cancer in at risk individuals (event time
65 years) compares well with 50% cumulative survival for
the subgroup of individuals who develop pancreatic cancer
(event time 62 years). Analysis of all individuals from each
family showed a reduction in survival of later generations
compared with their ancestors (log rank x
2
2
= 74.21,
p,0.001) (fig 3A). Median (95% confidence interval) age at
which 50% of family members in G1, G2, and G3 were
affected was 87 (85, 89), 74 (72, 76), and 61 (59, 63) years,
respectively. A similar effect was observed using birth cohorts
(log rank x
2
2
= 40.42, p,0.001) (fig 3B).
Birth cohort 1900–1919 included all relatives who by 2004
would be aged 85–94 years, the 1920–39 cohort would have
individuals aged 65–74 years, but the 1940–69 cohort only
had individuals aged 35–64 years. Any analyses based on
these observed data will necessarily miss the events that
would occur in the next 20 years, resulting in apparent
anticipation. Although there is overlap between the dates of
birth of G1, G2, and G3 populations (fig 2), a similar bias
exists for generations.
Truncation analysis on a subset of individuals who had
been observed for an equal 60 year period (individuals born
up to the year 1943), also showed a significant difference
between the groups defined by generation (log rank
x
2
2
= 16.93, p = 0.002) (fig 3C) but not for the birth cohorts
(log rank x
2
2
= 2.72, p = 0.6) (fig 3D). This is an improve-
ment on the Kaplan-Meier analysis described above but is
still subject to ascertainment bias; the small number of
cancer cases in G3 may reflect unusual cases while the
Table 2 Apparent anticipation with successive generations based on analysis of
succeeding generations and cohorts by year of birth
Generation n
Age of
death (y)* Cohort
Date of
birth n
Age of
death (y)
G1 50 70 (59, 77) C1 1900–19 53 70 (61, 76)
G2 158 64 (57, 69) C2 1920–39 136 64 (57, 69)
G3 53 49 (44, 56) C3 1940–69 62 50 (46, 55)
*Values are median (interquartile range).
Affected individuals were grouped according to generation (see text) or by date of birth.
All differences were significant: Kruskal-Wallis p,0.001 for generations and cohorts; Mann-Whitney U, p,0.001
for G1 versus G2, G2 versus G3, and G1 versus G3, and C1 versus C2, C2 versus C1, and C1 versus C3. This
clearly could be due to bias of ascertainment and truncation effects of age at death in G2 and G3 compared with
G1.
0
10
20
30
40
50
60
70
80
1880 1920 1960 2000
Year of birth
G1 n=71
G2 n=309
G3 n=448
% of generation
Figure 2 Distribution of all individuals in the three generations (G1,
G2, and G3) based on year of birth. Median year of birth (interquartile
range) of G1 =1909 (1903, 1914), G2 = 1930 (1925, 1936), and
G3 = 1950 (1950, 1957) years.
254 McFaul, Greenhalf, Earl, et al
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Page 3
majority of G3 individuals who are not affected are not taken
into consideration. To allow for this we used the matched test
statistic of Hsu and colleagues.
35
This scores individuals
(affected or unaffected) according to consistency with
anticipation. Differences between G1 and G2 and G2 and
G3 were both significant (p,0.001). However, this does not
take into account the likelihood that an individual is a gene
carrier (and so at high risk). Later generations have a higher
ratio of unaffected carriers to non-carriers, potentially giving
bias.
A novel iterative approach to test for anticipation
If there is no generation effect (for example, anticipation) on
the age of death from pancreatic cancer, the age related
penetrance function for carriers from one generation could be
used to predict the number of pancreatic cancer cases seen in
any other generation (regardless of the period of observa-
tion). Individual pancreatic cancer risk (p
i
) for each
individual (i) can be calculated by multiplying the probability
of an individual being a gene carrier by the respective age
related penetrance to time of observation. For any generation
124
381
389
120
370
207
117
323
49
105
223
4
73
72
0
G1
G2
G3
68
191
257
65
183
160
62
166
50
54
118
0
22
32
0
1900-19
1920-39
1940-69
Group at riskGroup at risk
124
283
30
121
277
28
118
269
27
78
237
18
G1
G2
G3
68
191
23
66
177
22
63
170
22
52
137
11
1900-19
1920-39
1940-69
Group at riskGroup at risk
35
0
20
40
60
80
100
30 40 50 60 30 40 50 60
45 55 65 75 35 45 55 65 75
Age (years) Age (years)
Age (years)Age (years)
% survival
0
20
40
60
80
100
% survival
0
20
40
60
80
100
% survival
0
20
40
60
80
100
% survival
AB
CD
No at risk, affected
G3 n=46953
G2 n=395158
G1 n=12550
No at risk, affected
G3 n=3210
G2 n=28525
G1 n=1259
No at risk, affected
G3 n=238
G2 n=19340
G1 n=6911
No at risk, affected
G3 n=26062
G2 n=193136
G1 n=6953
Figure 3 Kaplan-Meier survival analysis of individuals from different generations and date of birth based cohorts. The numbers below the graphs
show the number of family members from each group at each time point who were considered in the survival analysis. (A) Age of death of individuals
was significantly different between generations G1, G2, and G3 (989 at risk, 261 affected; log rank x
2
2
= 74.21, p,0.001). (B) Age of death of
individuals was significantly different between date of birth based cohorts (522 at risk, 251 affected; log rank x
2
2
= 40.42, p,0.001). (C) Age of death
of individuals with an observation period restricted to 60 years (all born before 1943) was significantly different between generations G1, G2, and G3
(442 at risk, 44 affected; log rank x
2
2
= 16.93, p = 0.002). (D) Age of death of individuals with an observation period restricted to 60 years (all born
before 1943) was not significantly different between the three birth cohorts (285 at risk, 59 affected; log rank x
2
2
= 2.72, p = 0.6).
30 50 70 90
Age (years)
30 50 70 90
Age (years)
0
20
40
60
80
100
% survival
0
20
40
60
80
100
% survival
G1 n=12550
G2 Uncensored
n=50
Regression
survival =
100-(age × 2.55 – 1.23)
G1 n=395158
G2 Uncensored
n=158
Regression
survival =
100-(100 × e
ln(age) × 5.35 – 23
)
AB
Figure 4 Actual survival data compared with estimates based on age related penetrance. (A) For the purposes of estimating age related penetrance, it
was assumed that a carrier had no risk of cancer until the age of 55 years and from then to the age of 90 years the risk increased linearly:
12([age60.0255]21.2). This is empirically based on the survival (birth to death) data curve and is not based on any assumed biological model or on
literature sources. It is not assumed to have any merit other than as a tool to estimate age dependent risk. After the age of 90 years a carrier was
assumed to have a risk of 1 (100% chance of being affected). For comparison, a regression is also shown using data from both censored (as yet
unaffected) and uncensored (affected) individuals. (B) Curve used to derive another empirical formula with a greater age related risk, based on
uncensored data from G2 (see table 3).
Anticipation in pancreatic cancer 255
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within a family there will be a number of possible
configurations of diagnoses. For each configuration, all
individuals (regardless of their actual diagnosis) are assigned
a state (cancer or non-cancer); hence for N individuals there
will be 2
N
configurations. The probability of each individual
having the defined state is either p
i
(cancer) or 12pi (no
cancer). The probability (c
g
) of obtaining a configuration can
be calculated by multiplying all of the individual probabilities
within that generation. Thus the probability for observing n
cancer cases in a generation would be the sum of all c
g
for a
configuration, giving n cases.
Only the G1generation has been followed up sufficiently to
allow a realistic estimation of age related penetrance.
Survival of affected individuals (uncensored data) in the G1
cohort appeared to decline from the age of 50 years with a
linear gradient of 0.0255 (fig 4A). This is just a description of
what has happened in the past to this particular group and
provides one of many possible measures of age related
penetrance; the specific function is not crucial in the
following arguments. This measure of age related penetrance
would be predicted to be an overestimate, as it does not take
into account any individuals who would have later developed
pancreatic cancer but died from other causes. The parent,
sibling, or offspring of an affected person has a 50% chance of
being a carrier (in this analysis no consideration was given to
the disease status of the subject, just of their relatives). A
second degree relative has a 25% chance and so on.
The probability of an individual being affected in G1
(calculated by multiplying the carrier probability with the
risk defined just for uncensored individuals) was found to be
a slight overestimate (0.65 v 0.63 cases observed per family).
This did not represent a significant difference (two sided p
value, p = 0.37) and suggested that simple regression analysis
was adequate; clearly other formulae estimating age related
risk could be found that would also work. Even assuming
100% lifetime penetrance, prediction of the number of
affected individuals in subsequent generations would tend
to be an overestimate—assuming risk does not increase with
generation—as in G1 we have a higher ratio of affected to
unaffected individuals than in other generations. In fact, the
same analysis for G2 showed that there was an under-
estimate of the number of affected individuals (0.8 v 1.5 cases
observed per family in G2).
The difference between the calculated and observed
incidence of cancer in the different generations was
significant for G2 and G3 but not G1 (table 3). This means
that this measure of age related penetrance is effective for G1
and in order to be applicable to G2 and G3 the function
would have to be changed to give a greater risk. Thus the risk
of cancer death in later generations was genuinely higher
than in earlier generations.
To refine the test of anticipation, a second level of risk was
produced for generations other than G1. Regression analysis
to provide the best fit to the survival curve for G2 (fig 4B) was
12e
ln (age)65.35–23
. The whole population was then modelled
assuming a risk defined as the chance of being a carrier
multiplied by 12e
ln (age)65.35–23
(table 3). The difference
between expected and observed cancer incidence in G3 is
indicative of a further increase in risk for the third generation
but evidence for this is less conclusive. This analysis indicated
at least two risk categories: low where there is no earlier
generation with pancreatic cancer, high where there is a
single earlier generation, and perhaps a still higher risk group
where two preceding generations are affected.
Smoking and anticipation
To test if an increase in smoking habit might explain
anticipation, we compared the smoking habit of individuals
from the different generations. Later generations smoked less
than earlier generations (table 4) but this difference was not
Table 3 Results of simulation
Equation used to calculate estimate (E)
G1 (80 families)* G2 (106 families)* G3 (101 families)*
OE p O E p OE p
Low risk 0.65 0.374 1.52 0.82 ,10
26
0.5 0.09 ,10
26
E = Pr (12((age60.03)21.2)
(for age = 55–90) + Pr (for over 90)
High risk 0.63 1.14 0.003 1.52 1.32 0.417 0.5 0.13 0.028
E = Pr (1–e
ln (age)65.35–23
)
(for age = 40–75) + Pr (for over 75)
*Some families could not be included because of unreliable data on ages.
On average, there were six observed affected individuals in generation 1 (G1) from every 10 families, 15 from G2, and five from G3. Two classes of risk were
estimated (low and high) based on age and probability of being a carrier (Pr). This was used to estimate the number of affected individuals in each generation (E) E
was compared with the observed number of affected individuals per family (O). Two sided p values of less than 0.01 were taken to indicate that the estimated
values were not consistent with observed values. A risk calculation giving expected cases equivalent with observed values in G2 would overestimate expected
values in G1 and underestimate in G3. Clearly, a still greater risk could be assumed that would give a better estimate of G3 cancer incidence. This implies that age
related risk increased with each generation.
Table 4 Smoking did not appear to be a confounding factor leading to anticipation
Cohort Total
Non-smokers Current or ex-smokers % Smokers (of generation)
Affected Censored Affected Censored Affected Censored
All generations 211 22 59 42 88 66 60
G1 13 2 0 8 3 80 100
G2 71 11 12 24 24 69 67
G3 127 9 47 10 61 53 56
Only adults older than 16 years of age and those defined within generations (G1, G2, or G3) were included. A
higher number of both affected and unaffected (censored) individuals used tobacco in earlier generations than in
later generations but this was not significant (x
2
2
= 5.13, p = 0.08). None of the comparisons was statistically
significant, either in comparisons of generations (log rank x
2
1
= 0.44, p = 0.5) or comparisons of smoking with
affected status (Fisher’s exact probability test p = 0.44).
256 McFaul, Greenhalf, Earl, et al
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Page 5
significant (x
2
2
= 5.13, p = 0.08) and could possibly also be
explained by bias. Smoking data were only available for 64
affected individuals and the patient provided this informa-
tion directly in only eight cases; in the other 56 cases,
information was provided by spouses, children, and in four
cases by grandchildren. It is easier to be confident that a
relative is a smoker than to be confident that a relative has
never smoked. As we censored out all responses that were not
confident, there is a predicted bias for defining affected
individuals as smokers. Five of the self reporting affected
individuals were in G2; the remaining three were in G1. Four
(50%) of the self reporters defined themselves as non-
smokers while only 10 (18%) of the remaining affected
individuals were defined by relatives as non-smokers.
DISCUSSION
This study has clearly demonstrated the phenomenon of
anticipation in familial pancreatic cancer using analytical
techniques to minimise statistical artefact. Anticipation for
the development of pancreatic cancer was approximately six
years between the oldest and intermediate generation. This
compares with 22 years in nine of 28 families in a previous
study.
30
Anticipation observed could be the result of environmental
factors; the statistical methods used here do not exclude
participation of environmental factors or the existence of
competing causes for death in older generations. Only
smoking habit has ever convincingly been associated with
pancreatic cancer risk in both sporadic and familial pancrea-
tic cancer.
1 30 42–44
Although in our study there was no
significant association between smoking and cancer, this
could reflect a limitation of the data rather than evidence that
smoking does not influence cancer onset in these families.
Nevertheless, the decline in smoking habit, which was
observed with later generations, would act against anticipa-
tion and not in favour. In order for smoking to account for
anticipation, this trend would need not only to be artefactual
but would have to be reversed. Non-response bias due to
greater reliance on second person reporting for earlier
generations could give a trend to less smoking habit in later
generations but the trend is consistent with much larger and
less biased studies carried out on the general population.
45
Therefore, the only environmental factor established as being
an influence on pancreatic cancer onset is unlikely to explain
anticipation.
Genetic anticipation should be family specific so the
progress of individuals in one family towards an earlier
onset should not be relevant to the progression in another
family, unless there is a common founder in a recent
generation. A recent common founder is unlikely in this
study given the geographical diversity of the families.
Population based anticipation could be genetic if the number
of generations over which pancreatic cancer is penetrant is
limited; for example, an apparent founder, their children, and
grandchildren. By definition, any founder in generation three
(G3) would not be included in the study, as a family can only
be recruited on the basis of multiple cases of pancreatic
cancer. Similarly, no third generation affected individuals
(grandchildren) can be included in G1 as no subsequent
generation would have contained affected individuals.
Although this would still allow for some misclassification,
it would mean that the definition of the generations would
have some biological validity. Anticipation and generation
limitation have been reported in Li-Fraumeni syndrome,
where in more than 90% of families studied cancer
penetrance is limited to three generations
46
; limitation can
be explained by carriers dying before reaching childbearing
age, clearly not the case with pancreatic cancer patients in
our study.
Some inherited neurological diseases demonstrating antici-
pation
13 14
have been linked to genes with trinucleotide repeat
expansions becoming increasingly unstable in successive
generations.
33 47 48
The situation in cancer syndromes may be
more complex
18 33
and anticipation may be related to
epigenetic factors.
49
In hereditary breast cancer, BRCA2
mutation carriers have a greater degree of anticipation than
those without known mutations.
50 51
Mutations of the BRCA2
gene impair recombinational DNA repair; this may be
relevant to familial pancreatic cancer families with BRCA2
mutations.
11
Anticipation has also been reported in hereditary
non-polyposis colorectal cancer caused by mutations in
mismatch repair genes.
31
Anticipation in this study may be due to a DNA repair gene
other than BRCA2. This could account for a limitation in the
number of generations with penetrant pancreatic cancer. The
mutation in itself could be inadequate to result in an elevated
cancer risk but heterozygotes may accumulate other muta-
tions in their germline. A steady level of genetic damage will
be maintained by segregation of unlinked mutations with the
disease allele augmented by further mutations resulting from
repair deficiency. However, some new mutations will be
linked to the disease gene and so the level of genetic damage
overall will increase in carriers. A point may be reached (for
example, G1) where genetic damage weakens cell cycle
regulation resulting in cancer. Further accumulation of
damage would result in earlier development of cancer in
successive generations (hence anticipation). Eventually (for
example, following G3), accumulation of defects prevents
subsequent incidence of pancreatic cancer (for example,
prevents gametogenesis, is fatal in utero, or results in an
individual who develops other forms of cancer, potentially
excluding the recruitment of the family).
This study has described families from widely differing
environments in Europe and gives strong evidence for
anticipation in familial pancreatic cancer. These findings
may assist the creation of more informative family trees for
linkage studies. Finally, the results of this study have
immediate implications for genetic counselling and pancrea-
tic cancer screening in high risk individuals from familial
pancreatic cancer families.
ACKNOWLEDGEMENTS
This work was funded by grants from Cancer Research UK, Royal
Liverpool University Hospital, Augustus Newman Foundation, the
North West Cancer Research Fund, North West NHS Biomed
Research Committee, an MRC Gastroenterology and Pancreas
Research Co-operative Grant, and the Deutsche Krebshilfe 70-3085-
Ba4 Germany. There were no competing interests.
We are grateful for the work undertaken by L Vitone (EUROPAC Co-
ordinator), Margarete Schneider (FaPaCa study office), and
R Mountford and to the following who, in addition to the co-
authors, have provided families and ongoing clinical information:
Belgium: M Delhaye; Germany: L Este´ve´z-Schwarz W von Bernstorff,
M Colombo-Benkmann, W Bo¨ck, K Breitschaft, S Du¨lsner, T Eberl,
S Eisold, E Endlicher, M Ernst, L Este´ve´z-Schwarz, B Gerdes,
BM Ghadimi, TM Gress, R Gru¨tzmann, JW Heise, O Horstmann,
L Jochimsen, C Jung, H Messmann, R Metzner, T Mundel, K Prenzel,
OPrido¨hl, J Rudolph, KM Schulte, C Schleicher, J Schmidt,
K Schulmann, H Vogelsang H Witzigmann, N Zu¨gel; Hungary:
A Ola´h, V Ruszinko; Italy: D Campra, G Uomo, S Pedrazzoli; Norway:
A
˚
Andre´n-Sandberg; Netherlands: J Jansen; UK and Ireland: A Brady,
J Bennett, J Booth, L Botham, J Cahill, B Carmichael, C Chapman,
O Claber, W Crisp, M Deakin, T Cole, J Cook, L Cowley, H Cupples,
BR Davidson, G Davies, H Dorkins, DD Eccles, R Eeles, F Elmslie,
G Evans, S Fairgrieve, C Faulkner, J Foster A Howick, M Hershman,
S Hodgson, C Imrie, L Irvine, L Izatt, C Johnson, B Kerr, A Laucassen,
S Laws, D Longdon, R Loke, D McBride, J MacKay, E Maher,
M Mehta, C Mitchell, G Mitchell, P Morrison, K Pape, J Raeburn,
E Sheridan, C Smith, G Sobala, R Sutton, J Thomson, S Tomkins,
K Wedgwood P Zack; Sweden, E Bjorck, E Svarthol, J Permert, I Ihse.
Anticipation in pancreatic cancer 257
www.gutjnl.com
Page 6
Authors’ affiliations
.....................
C D McFaul*
, W Greenhalf*, J Earl, N Howes, J P Neoptolemos,
Division of Surgery and Oncology, University of Liverpool, Liverpool, UK
R Kress, Institute of Medical Biometry and Epidemiology, Philipps-
University, Marburg, Germany
M Sina-Frey, H Rieder, D K Bartsch, Department of Clinical Genetics,
Philipps-University, Marburg, Germany
S Hahn, Department of Internal Medicine, Knappschaftskrankenhaus
University of Bochum, Bochum, Germany
*C D McFaul and W Greenhalf contributed equally as principal
investigators.
Conflict of interest: None declared.
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  • Source
    • "Interestingly, the phenomenon of " anticipation , " which is a reduction in the age of onset of hereditary pancreatic cancer with successive generations, has been described in 59–85% of FPC families from studies by the European Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer and FaPaCa (German national case collection for FPC) registries (James et al., 2004; McFaul et al., 2006; Schneider et al., 2011). Analysis of 80 affected child-parent pairs by McFaul et al revealed the children died a median of 10 years earlier than the parent, thereby providing strong implications for genetic counseling and secondary screening per the authors (McFaul et al., 2006). "
    [Show abstract] [Hide abstract] ABSTRACT: Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer deaths in both men and women in the United States, carrying a 5-year survival rate of approximately 5%, which is the poorest prognosis of any solid tumor type. Given the dismal prognosis associated with PDAC, a more thorough understanding of risk factors and genetic predisposition has important implications not only for cancer prevention, but also for screening techniques and the development of personalized therapies. While screening of the general population is not recommended or practicable with current diagnostic methods, studies are ongoing to evaluate its usefulness in people with at least 5- to 10-fold increased risk of PDAC. In order to help identify high-risk populations who would be most likely to benefit from early detection screening tests for pancreatic cancer, discovery of additional pancreatic cancer susceptibility genes is crucial. Thus, specific gene-based, gene-product, and marker-based testing for the early detection of pancreatic cancer are currently being developed, with the potential for these to be useful as potential therapeutic targets as well. The goal of this review is to provide an overview of the genetic basis for PDAC with a focus on germline and familial determinants. A discussion of potential therapeutic targets and future directions in screening and treatment is also provided.
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  • Source
    • "Similarly, a registry-based prospective study from the European Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer (EUROPAC) and the German National Case Collection for Familial Pancreatic Cancer (FaPaCa) reported on 80 affected child–parent pairs, and found that the children died of their disease a median of 10 years earlier than did their parents. The median age of death from PC was 70, 64, and 49 years in Generations G1, G2, and G3 [45]. These observations are important for determining the most appropriate age at which to commence screening for PC in individuals at high-risk. "
    [Show abstract] [Hide abstract] ABSTRACT: Pancreatic cancer is still a highly lethal disease with a 5-year survival rate of approximately 5 %. Early detection offers one of the best hopes for improving survival. Previous cohort studies and case-control studies showed that 4-10 % of pancreatic cancers have a hereditary basis, and individuals with a family history have an increased risk of developing pancreatic and extra-pancreatic malignancies. Since individuals with a family history of pancreatic cancer and those with a known genetic syndrome that predisposes to pancreatic cancer will be the first to benefit from early detection tests as they become available, familial pancreatic cancer (FPC) registries have been established in the US and Europe, but not yet in Japan. Such registries form the basis for epidemiological studies, clinical trials, and basic research on familial pancreatic cancer. There is a need for FPC registries in Japan as cancer risk varies among different populations and discoveries made in Western populations may not translate to the Japanese population. These registries in Japan will align with ongoing international efforts and add to a better understanding of the natural history, risk factors, screening strategies, and responsible genes, for improving survival of this dismal disease.
    Full-text · Article · Apr 2013 · Journal of Hepato-Biliary-Pancreatic Sciences
  • Source
    • "Applying the screening principles of colorectal cancer by beginning screening for pancreatic cancer 10 years earlier than the youngest affected member in the family is a reasonable starting point. Taking into account, however, the long time between initiation of a PDAC tumor cell and the presence of a PDAC tumor beginning to have metastatic capability (11.7 ± 3.1 years [62]), and taking into account evidence that consecutive generations with FPC die of PC a median of 10 years sooner each subsequent generation [63], and finally taking into account that smokers with FPC develop cancer a decade before nonsmokers, it is reasonable to use judgment in screening selected individuals much earlier. A reasonable screening algorithm is presented inFigure 1. "
    [Show abstract] [Hide abstract] ABSTRACT: Hereditary etiologies of pancreatic and hepatobiliary cancers are increasingly recognized. An estimated >10% of pancreatic and increasing number of hepatobiliary cancers are hereditary. The cumulative risk of hereditary pancreatic cancer ranges from measurable but negligible in cystic fibrosis to a sobering 70% in cases of hereditary pancreatitis. Candidates for pancreatic cancer surveillance are those with a risk pancreatic cancer estimated to be >10-fold that of the normal population. Screening for pancreatic cancer in high-risk individuals is typically performed by endoscopic ultrasound and should begin at least 10 years prior to the age of the youngest affected relative. Disease states known to be associated with increased risk of hepatocellular cancer include hereditary hemochromatosis, autoimmune hepatitis, porphyria, and α1-antitrypsin deficiency, with relative risks as high as 36-fold. Although much less is known about hereditary bile-duct cancers, Muir-Torre syndrome and bile salt export pump deficiency are diseases whose association with hereditary carcinogenesis is under investigation.
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