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Acta Oncologica
ISSN: 0284-186X (Print) 1651-226X (Online) Journal homepage: http://www.tandfonline.com/loi/ionc20
Temporal trends in the use of adjuvant systemic
therapy in breast cancer – a population based
study in Sweden 1976–2005
Levent Kemetli, Lars Erik Rutqvist, Håkan Jonsson, Lennarth Nyström, Per
Lenner & Sven Törnberg
To cite this article: Levent Kemetli, Lars Erik Rutqvist, Håkan Jonsson, Lennarth Nyström, Per
Lenner & Sven Törnberg (2009) Temporal trends in the use of adjuvant systemic therapy in
breast cancer – a population based study in Sweden 1976–2005, Acta Oncologica, 48:1, 59-66
To link to this article: http://dx.doi.org/10.1080/02841860802277471
Published online: 08 Jul 2009.
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ORIGINAL ARTICLE
Temporal trends in the use of adjuvant systemic therapy in breast
cancer
a population based study in Sweden 1976
2005
LEVENT KEMETLI
1
, LARS ERIK RUTQVIST
2
,HA
˚
KAN JONSSON
3
,
LENNARTH NYSTRO
¨
M
4
, PER LENNER
3
& SVEN TO
¨
RNBERG
1
1
Oncologic Centre of Stockholm-Gotland, Karolinska University Hospital & Institute, Stockholm, Sweden,
2
Department of
Oncology-Pathology, Karolinska Institute, Stockholm, Sweden,
3
Department of Radiation Sciences, Oncology, Umea
˚
University Hospital, Umea
˚
, Sweden and
4
Department of Public Health and Clinical Medicine, Epidemiology and Public
Health Sciences, Umea
˚
University Hospital, Umea
˚
, Sweden
Abstract
Background. Both adjuvant therapy and mammography screening can decrease breast cancer mortality and there is a need of
knowing to what extent those two modalities are used in the population. Screening coverage is well documented but there is
a scarcity of population-based data on use of systemic adjuvant treatment. Aim. To describe the introduction, and trends in
the use of adjuvant systemic therapy for breast cancer in two of six public health regions in Sweden. Material & methods.
Population-based data on use of adjuvant therapy were available from databases with documented high quality and high
coverage data for Stockholm (19762005) and North Sweden (19802003, and 2005). Results. The use of systemic
treatment was infrequent before the late 1980s in both regions, but increased during the 1990s. In 2005, the proportion of
operable breast cancer patients treated with adjuvant endocrine therapy in the ages 4059 was around 60 to 80%. The
proportion adjuvant chemotherapy was less than 15% for the ages 7074. For the north region the use of endocrine therapy
increased successively over time, with an exception for age group 4049 were a more rapidly increase occurred in the late
1990s. In Stockholm the increment was higher and more rapidly. There was no clear difference in chemotherapy use
between the regions, and the use increased from the mid 1980s in age group 4049, and in the early 1990s for women aged
5059. In age group’s 6069 and 7074 the use was relatively infrequent. Conclusions. Trends in, and levels of the use of
adjuvant systemic therapy for breast cancer varied over time in the two study regions, particularly for endocrine therapy. We
consider that the differences between the regions mainly reflect different interpretations of new scientific evidence. We stress
the importance of a good documentation of all new treatment protocols.
The secular trend for age-adjusted breast cancer
mortality has shifted in several western countries
during the 1990s. The trend is now distinctly
downward in, for instance, the UK and the US,
despite continuing increases in the breast cancer
incidence, except for the last 23 years [1]. There
has been considerable controversy regarding the
extent to which preventive measures such as early
diagnosis and widespread use of routine adjuvant
systemic therapy has contributed to the decreasing
trend in breast cancer mortality. Over the years
several randomised controlled trials (RCTs) and
overviews and meta-analyses of such trials have
convincingly demonstrated that both mammography
screening and adjuvant systemic therapy can de-
crease breast cancer mortality and case fatality
[27].
In Sweden, breast cancer mortality has been stable
or slightly downward during past decades while at
the same time breast cancer incidence has increased
substantially. This has been explained by the intro-
duction of population-based mammography screen-
ing as well as the increasing use of systemic adjuvant
therapy. The population-based screening program
with mammography in Sweden is well documented
in several studies [811]. However, as in many other
countries, there are limited data on time trends in
the use of adjuvant systemic therapy. The time
Correspondence: Levent Kemetli, Cancer Screening Unit, Oncologic Centre M8, Karolinska University Hospital, 171 76 Stockholm, Sweden. Tel: 46 8 517
733 64. Fax: 46 8 32 77 60. E-mail: levent.kemetli@karolinska.se
Acta Oncologica, 2009; 48: 5966
(Received 3 April 2008; accepted 16 June 2008)
ISSN 0284-186X print/ISSN 1651-226X online # 2009 Informa UK Ltd. (Informa Healthcare, Taylor & Francis AS)
DOI: 10.1080/02841860802277471
Downloaded by [14.192.128.178] at 15:15 25 January 2016
trends in adjuvant therapy has so far only been
reported from the Netherlands (19731997) [6],
southeast England (19962003) [12], and from the
US (19751999) [13], where all authors expressed
problems in obtaining high quality and high coverage
data on adjuvant therapy.
Both mammography screening and adjuvant sys-
temic therapy were introduced as part of routine
health care in many countries during roughly the same
time period, i.e., adjuvant systemic therapy in the late
1970s and mammography screening in the late 1980s
through the early 1990s. The aim of the present study
was to analyse secular trends in the use of adjuvant
systemic therapy among patients with breast cancer,
in two of six public health care regions in Sweden
(Stockholm and North Sweden) 19762005.
Material and methods
Cancer care in Sweden is coordinated by central
units organised at a regional level in the six different
public health care regions. Despite a nationwide
common view of what would be the golden standard
and national recommendations and guidelines in
breast cancer treatment, the different regions may
have their guidelines adjusted for regional differ-
ences. Data in the present study derives from the two
regions, Stockholm and North Sweden.
Stockholm
Study area. Stockholm is a mainly urban area with a
population of about 1.8 million. The annual number
of incident cases of invasive breast cancer increased
from about 800 in the late 1970s to about 1 500 in
the year 2005 [14].
Breast cancer care program. Breast cancer care in the
region is coordinated through a comprehensive
breast cancer care program initiated in the mid
1970s. The program is organised by the multi-
disciplinary Stockholm Breast Cancer Study Group
(SBCSG) and includes clinical practice guidelines
implemented at the five breast cancer detection and
treatment centres. Over the years, the SBCSG has
initiated several RCTs on adjuvant therapy.
Breast cancer care database. A clinical database was
initiated in 1976 aiming at prospectively include all
women with primary breast cancer diagnosed in the
region. It is based on reports from all clinicians
collaborating with the SBCSG. The data registered
include information on stage of disease at primary
diagnosis, type of surgery, postoperative treatment
(including adjuvant systemic therapy), histopatholo-
gical data, hormone receptor status and follow-up
data. The completeness of the registers is checked
through record linkage with data from the Regional
Cancer Registry in the Stockholm-Gotland region
which reports to the nationwide Swedish Cancer
Registry. The completeness of the register at the
National Cancer Registry has been estimated at
96% [15].
The breast cancer database includes prospectively
collected information on the use of adjuvant sys-
temic treatment among individual patients. Report-
ing was based on forms filled out by the responsible
clinician in conjunction with the multidisciplinary,
postoperative clinical conference. The recom-
mended treatment was then discussed with the
patient at the out-patient clinic a few days later.
This implied that the treatment actually received by
the patient may have deviated from the intended
treatment reported on the form sent to the SBCSG
secretariat. However, such inconsistencies have been
found to be rare. For instance, among patients who
were recommended treatment with tamoxifen, 96%
were found to have initiated such treatment, and
among those not recommended such treatment, only
1% actually received the drug [16]. Non-compliance
to a recommendation of adjuvant chemotherapy was
in 19761984 found to be about 6 and 10% among
pre- and post menopausal patients, respectively [17].
Breast cancer care guidelines. The clinical practice
guidelines issued by the SBCSG are intended to be
evidence-based. Consequently, they have been con-
tinuously updated to comply with the increase of
evidence from the RCTs on adjuvant systemic
therapy and overviews of such RCTs. Routine
adjuvant systemic therapy was not recommended
until 1990. At that time, the survival benefits
observed in the Oxford overviews with both cytotoxic
chemotherapy and adjuvant endocrine therapy were
considered mature and clinically worthwhile [2,3].
North Sweden
Study area. North Sweden is a mainly rural area. It
covers about half of Sweden but the population is only
0.9 million. The annual number of incident cases of
invasive breast cancer increased from about 400 in
the late 1970s to about 600 in the year 2005 [14].
Breast cancer care program. As in Stockholm breast
cancer care in the region is coordinated through a
comprehensive breast cancer program. The program
was initiated in 1980 and is organised by the multi-
disciplinary North Sweden Breast Cancer Group
(NSBG). Similar to the SBCSG the NSBG has
60 L. Kemetli et al.
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initiated several RCTs on adjuvant therapy as part of
the program.
Breast cancer care database. As part of the regional
breast cancer program a clinical database was
initiated in 1980 aiming at prospectively include
women with primary breast cancer diagnosed in the
region. The format of the database is similar to that
in Stockholm. The completeness of registration is
checked through record linkage with data from the
Regional Cancer Registry, also delivering the regio-
nal data to the National Cancer Registry.
In North Sweden, registered data were also based
on forms filled out by the responsible clinician.
However, all information on adjuvant systemic
treatment has prospectively been checked for accu-
racy by data managers who have compared the
registered information with clinical records. This
routine has been implemented since September
1987 when the database was changed. The regis-
tered information from 1988 and onwards thus
concerns the type of adjuvant systemic therapy that
was actually initiated in a patient. However, before
that year, information about treatment mostly con-
cerned the treatment allocated to patients included
in the RCTs. As adjuvant systemic therapy during
this time was rarely used outside the trials, it was
assumed that patients for whom data were unavail-
able had not received adjuvant systemic therapy.
During 19801987 the county of Ja
¨
mtland, which
then constituted 15% of the female population in the
region did not belong to the region and were not
included in the clinical breast cancer database.
Therefore, Ja
¨
mtland was excluded from the analysis
during that period. The registration in the breast
cancer care database for the year 2004 was not yet
complete and could therefore not be included in the
analyses.
Breast cancer care guidelines. In North Sweden the
regional clinical practice guidelines issued by the
NSBG have been continuously updated. Routine
adjuvant systemic therapy in selected patient groups
was recommended first in 1987.
Adjuvant therapy
Study population/period. For this study we selected
women aged 4074 years who were reported to the
breast cancer database 19762005 in Stockholm
and 19802005 in North Sweden with a uni- or
bilateral, primary, invasive breast cancer, and who
were considered to have operable disease. Adjuvant
treatment with tamoxifen, megestrol acetate, me-
droxyprogesterone acetate, and goserelin or oophor-
ectomy among pre menopausal patients, was
recorded as ‘adjuvant endocrine therapy’ irrespective
of whether they also were treated with adjuvant
chemotherapy. Adjuvant therapy with cytotoxic
drugs (typically CMF-type regimens during the
1970s and early 1980s, and anthracycline-containing
regimens during the late 1980s and 1990s) was
recorded as ‘adjuvant chemotherapy’ irrespective of
whether the patient also received adjuvant endocrine
therapy. Patients receiving both treatment modal-
ities, either in combination or sequentially were
recorded as having had ‘adjuvant chemo-hormonal
therapy’.
The study was approved by the Karolinska In-
stitute’s Research Ethics Committee (KI Dnr: 03-
630). The approval was valid for both regions.
Results
Coverage of the breast cancer care databases
During the study period 19762005, 23 156 invasive
breast cancer cases aged 4074 years were reported
to the Regional Cancer Registry in Stockholm and
out of these, 21 639 were notified in the breast
cancer care database, thus giving registration cover-
age of 93%. The coverage was lower during the first
three years (in the late 70s), but remained at a high
and stable level thereafter. A total of 92% had
undergone primary surgery, and among them in-
formation on adjuvant systemic therapy was avail-
able in 98% of the patients between the years 1991
and 2005.
During the period 1976 to 1990 the registration of
the data variable ‘‘no adjuvant therapy given’’ could
not be separated from the variable ‘‘adjuvant therapy
unknown’’. This explains why the curve in Figure 1 is
at a lower level before 1991. There is no reason
to believe that the registration was less complete
before 1990, therefore the level shown would likely
be false too low. The proportion of operable cases
with information on adjuvant therapy remained high
and stable during the entire period (Figure 1).
In North Sweden 8 714 invasive breast cancer
cases aged 4074 years were reported to the Regional
Cancer Registry 19802005 (2004 excluded) com-
pared to 8 543 in the breast cancer care database
(98% coverage). The proportion of cases that under-
went primary surgery was 91%. As in Stockholm this
proportion did not change substantially during the
study period (Figure 1). Data on adjuvant systemic
therapy was available in 96% of the patients for the
period 1988 to 2005, but during 1980 to 1987 data
were available only for patients included in RCTs.
However, the vast majority of the patients treated
outside the trials did not receive adjuvant therapy as
Trends in the use of adjuvant breast cancer therapy 61
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it was not recommended in routine practice at the
time.
Ages 4049 years
Before 1990 few patients in Stockholm below the age
of 50 years were treated with adjuvant endocrine
therapy (Figure 2) whereas 1020% received adju-
vant chemotherapy (Figure 3). In Northern Sweden
1525% received endocrine treatment during the
1980s whereas the use of chemotherapy was less
prevalent, 510%.
During the 1990s the use of both adjuvant endo-
crine and cytotoxic therapy increased substantially in
Stockholm
0
200
400
600
800
1000
1200
1975 1980 1985 1990 1995 2000 2005
Year
Number of cases
North Sweden
0
200
400
600
800
1000
1200
1975 1980 1985 1990 1995 2000 2005
Year
Cancer register
Breast cancer register
Operated
Information about adjuvant therapy
Figure 1. The annual number of invasive breast cancer cases in Stockholm county 19762005 (Stockholm), and in North Sweden 1980
2005 (North Sweden), in the ages 4074: 1) reported to the Swedish Cancer Registry, 2) included in the regional breast cancer database,
3) registered as operable, and 4) with information on adjuvant therapy.
40-49
0
20
40
60
80
100
1975 1980 1985 1990 1995 2000 2005
Percentage
50-59
0
20
40
60
80
100
1975 1980 1985 1990 1995 2000 2005
60-69
0
20
40
60
80
100
1975 1980 1985 1990 1995 2000 2005
Year
Percentage
70-74
0
20
40
60
80
100
1975 1980 1985 1990 1995 2000 2005
Year
North Sweden
Stockholm
Figure 2. The proportion of operable breast cancer cases aged 4049, 5059, 6069 and 7074 years treated with adjuvant endocrine
therapy according to year of diagnosis and region.
62 L. Kemetli et al.
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both regions. The proportion who received che-
motherapy was about the same in Stockholm and
North Sweden, and about 50% received such therapy
in the year 2005. The use of adjuvant endocrine
therapy increased markedly in Stockholm during the
early 1990s to about 5060%. In approximately 40%
of these cases the treatment was given in conjunction
with chemotherapy (Figure 4). A similar sharp
increase in the use of adjuvant endocrine therapy
was observed in North Sweden but not until the late
1990s. About half, to two-thirds of the patients
received chemo-hormonal therapy.
Ages 5059 years
During the late 1970s and 1980s the use of adjuvant
endocrine therapy in both regions was fairly stable
and covered 2030% of the patients (Figure 2).
40-49
0
20
40
60
80
100
1975 1980 1985 1990 1995 2000 2005
PercentagePercentage
50-59
0
20
40
60
80
100
1975 1980 1985 1990 1995 2000 2005
60-69
0
20
40
60
80
100
1975 1980 1985 1990 1995 2000 2005
Year
70-74
0
20
40
60
80
100
1975 1980 1985 1990 1995 2000 2005
Year
Figure 3. The proportion of operable breast cancer cases aged 4049, 5059, 6069 and 7074 years treated with adjuvant chemotherapy
according to year of diagnosis and region.
40-49
0
20
40
60
80
100
1975 1980 1985 1990 1995 2000 2005
Year
Percentage
50-59
0
20
40
60
80
100
1975 1980 1985 1990 1995 2000 2005
Year
North Sweden
Stockholm
Figure 4. The proportion of operable breast cancer cases aged 4049 and 5059 years treated with adjuvant endocrine therapy and
chemotherapy according to year of diagnosis and region.
Trends in the use of adjuvant breast cancer therapy 63
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However, during the early 1990s the use increased
sharply in Stockholm up to 7080%, and remained
stable during the remaining study period. No similar
sharp upward trend was observed in North Sweden
although there was a small increase in the use of
endocrine therapy in the late 1990s and a continuing
increment up to 55% in 2005.
The use of adjuvant chemotherapy was 1015%
until the mid 1990s in both regions and increased
gradually to approximately 35% the year 2005
(Figure 3). About half of the therapy was combined
chemo-hormonal therapy (Figure 4).
Ages 6069 years
In Stockholm the trend in the use of endocrine
therapy in age group 6069 was similar to that
observed in the women aged 5059 (Figure 2). In
contrast, only a small increase was observed in
North Sweden.
Adjuvant chemotherapy was rarely used in this age
group during most of the study period (Figure 3).
The trends were not substantially different between
the two regions. During the 1980s only 510% of the
cases received such treatment and the time trends
were actually slightly downward. However, since the
late 1990s there appeared to be some increase in
usage. In the year 2005, 1530% of the women
received adjuvant chemotherapy in both regions.
Because of the infrequent use of chemotherapy in
this age group, rates for combined chemo-hormonal
therapy were also low (data not shown).
Ages 7074 years
Trends in the use of endocrine therapy in this age
group were roughly similar to those observed at ages
5059 years and 6069 years: i.e. relatively stable
around 1020% until the late 1980s thereafter it
increased sharply in Stockholm to about 80%
(Figure 2). In North Sweden use increased to
some extent also during late 1980s to early 1990s,
but levelled off at 4050% during the 1990s. In the
year 2005 the proportion was under 40%.
Only few patients in this age group received
adjuvant chemotherapy during the study period
(Figure 3).
Discussion
Before conducting this study we had an assumption
that new scientific evidence on systemic breast
cancer therapy would have an immediate impact
on treatment regimens, however, that assumption
could not be confirmed.
Already in the mid 1970s preliminary results from
controlled trials suggested significant and clinically
worthwhile treatment benefits with adjuvant che-
motherapy in early stage breast cancer [18,19]. A
few years later encouraging results were also re-
ported from trials of adjuvant endocrine therapy
with tamoxifen [20,21]. Against this background one
would perhaps have expected upward trends in use
of adjuvant systemic therapy starting already in the
late 1970s to early 1980s. It would also seem
reasonable to assume that such upward trends were
accentuated after 1985 following the recommenda-
tions of the National Institutes of Health/National
Cancer Institute (NIH/NCI) Consensus Develop-
ment Conference about routine use of adjuvant
chemotherapy and adjuvant tamoxifen [22]. Despite
the availability of such guidelines there is evidence
that adherence to and implementation of treatment
recommendations is less than optimal. This has also
been described by other authors [23]. The present
study shows that all types of adjuvant systemic
therapy were used relatively infrequently before the
late 1980s. Upward trends in the use of adjuvant
therapy did not occur before the early 1990s.
However a pattern in the use of adjuvant therapy
reflecting a high degree of compliance to the regional
practice guidelines who did not recommend adju-
vant systemic therapy as a routine treatment before
1987 in North Sweden, and before 1990 in Stock-
holm were also seen in this study. In Stockholm, the
correlation between regional guidelines and endo-
crine therapy is striking. This is most obvious in the
youngest age group where endocrine therapy was not
recommended to pre menopausal women before
1990. However, after 1990 a large increase was
seen in all the age groups. After 1996 a slight change
in the curves is seen due to a revision version of the
guidelines. In the north region the changes in the
curves were not as large and instantaneous as in
Stockholm. Another difference between the two
regions was the larger variability in North Sweden,
which could be due to the lower number of cases
there, in comparison to Stockholm.
We also studied the pTNM stage, and oestrogen
receptor (ER) status distributions for the two regions
in order to search explanation for the differences in
adjuvant systemic therapy between the two regions.
However, both the stage distribution and the dis-
tribution of ER were rather similar between the
regions (data not shown), and none of them could
explain the differences between the regions.
In the present study the figures of systemic
adjuvant therapy is presented as a proportion of
operable breast cancer cases. The reason for using
this proportion instead of all breast cancer cases as
the denominator used in other studies [6,12,13] was
64 L. Kemetli et al.
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the fact that inoperable cases would not benefit from
receiving adjuvant therapy. The disadvantage with
this proportion is that it is not easily compared with
other studies, the advantage of this proportion is that
it is more refined and should better be related to the
outcome. In this study 84 to 93% of the breast
cancer cases where operated throughout the study
period.
The trend in North Sweden and Stockholm
concerning adjuvant chemotherapy was similar to
that in the south east of the Netherlands [6]. Despite
similar health care organisation and access to region
wide cancer statistics in Sweden and in the Nether-
lands, the proportion of women below 50, treated
with chemotherapy in the Netherlands was higher
than in Sweden before the 1990. In that age group
the percentage of women treated with tamoxifen was
around 5% at maximum for the whole period, which
was completely different from what was seen in the
two Swedish regions.
Data reported from the southeast England [12],
was not divided into age groups which obstruct the
comparability with the present study. Tataru et al.
reported a relatively steep decrease in hormone
therapy during the late 1990s and early 2000s, which
was not seen in the two Swedish regions. For
chemotherapy the differences were not as striking
as for hormonal therapy. It’s reasonable to believe
that the differences seen on hormonal therapy are
due to stricter treatment criteria in England during
this period. In Sweden, also pre menopausal women
with ER positive breast cancers have been treated
with tamoxifen, where in England, only post meno-
pausal women receive tamoxifen.
Trends in adjuvant therapy in the US were
reported from eight population-based registries
[13], for a time period similar to the present study.
The health care organisation in the United States is
more privately based allowing physicians to act more
freely in the decision on type of treatment to
recommend the individual patient. This makes data
from that study difficult to compare with ours. The
US data was presented by stage: still a very sharp
increase in hormonal therapy was seen a couple of
years before the increase occur in Stockholm. This
could probably be due to the already mentioned
difference in health care organisation where in the
US, new methods and recommendations was
adopted earlier than in more centralised health care
system.
The study had several strengths. It was based on
almost three decades of population-based clinical
data of diagnosed breast cancer cases, covering a
third of the Swedish population. Prospectively col-
lected data were available from the late 1970s until
the mid 2000s. Initially adjuvant systemic therapy
was only used in selected patients included in
controlled clinical trials. Later, it was routinely
used in a larger proportion of all the cases.
It might be seen as a limitation that we did not
analyse the trends in more detail. Such an approach
would have been necessary if the aim of this study
had included assessing the extent to which the
treatment offered to the patients adhered to the
clinical practice guidelines issued by the regional
breast cancer groups. North Sweden reported ad-
juvant therapy as ‘‘actually initiated’’ to the patient
whereas in Stockholm treatment was reported as
‘‘recommended’’ to the patient. However, in reality
the possible differences between the regions in
whether the patients had received treatment or not
are probably small because previous experience
from Stockholm indicated that the patients’ com-
pliance to recommended treatment was high, parti-
cularly in the case of adjuvant endocrine therapy.
There is therefore no reason to assume any differ-
ences between the two regions in the percentages
of patients having received complete treatment
[16,17]. Nevertheless, we can not exclude that this
circumstance may cause a small overestimate of the
reported proportions treated patients in Stockholm
in comparison to North Sweden.
The upward trends in use of adjuvant systemic
therapy in the early 1990s occurred roughly simul-
taneously with the introduction of population-based
mammography screening. The screening program in
Stockholm started 1989 (age 5069) and the first
round was completed in 1991. In North Sweden
screening started 19891990 (age 4074) in two
of the counties (59% of the total population).
Their first round was completed in early 1992.
The remaining two counties in the northern region
started mammography screening in the mid 1990s
(age 5069), and in 1998 all women in the target
group in the region had been screened at least once.
This implies that service screening was introduced in
both regions concurrently with a more widespread
use of adjuvant systemic therapy. In fact the intro-
duction of screening which is believed to result in
a down staging of the diagnosed breast cancers
[24], may also have had an influence on both type
and amount of therapy that has been given there-
after.
The trends in adjuvant systemic therapy in the
North Sweden and Stockholm, reported in the
present study have to our knowledge not been
shown before. Actually given adjuvant systemic
therapy varied between the regions, particularly
for endocrine therapy. We consider that these
differences between the regions were mainly due
to different interpretations of new scientific evi-
dence. However, we were unable to verify this with
Trends in the use of adjuvant breast cancer therapy 65
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information back in time when new treatment
protocols had been issued. In order to maximise
the use of individual data registers for evaluation of
treatment effects we would emphasize the need of
a systemic documentation of when, and for which
patient groups new treatment regimens are agreed
and issued.
Acknowledgements
This study was supported by a grant from the
Swedish Cancer Society.
None of the authors have declared any conflict of
interest
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