Peer reviewed article
SWISS MED WKLY 2010;140(15–16):233–236 · www.smw.ch
Incidental detection of synchronous primary
tumours during staging workup for prostate
Orhan Özsoya, Gérald Fiorettab, Carmen Aresa, Raymond Miralbella
aRadiation Oncology Service, Geneva University Hospitals, Geneva, Switzerland
bGeneva Cancer Registry, Institute for Social and Preventive Medicine, University of Geneva, Geneva,
Questions under study: To assess the prevalence
of incidental synchronous primary cancers discov-
ered by abdominal CT scan among prostate can-
Methods: Patients with prostate cancer in Ge-
neva, Switzerland, were retrospectively analysed
regarding incidental diagnosis of synchronous
second primary malignancies, including a cohort
of 398 patients treated from 1991 through 2001
with radical radiotherapy (RT) and a second co-
hort of 419 patients treated from 1991 through
2001 by radical prostatectomy (RP) in order to an-
alyse the differences between RT and RP patients.
Both cohorts were evaluated regarding incidence
of synchronous second primary cancers,compared
with that expected in the general population
(Standardized Incidence Ratio, SIR). The influ-
ence of staging workup on the diagnosis of inci-
dental primary malignancies was studied.
Results: Six synchronous cancers (4 renal, 1
pancreatic, 1 rectal) were observed on abdomino-
pelvic CT-scan among 480 patients (398 RT pa-
tients and 82 RP patients) (1.2%), who had been
subjected to staging workup. For renal-cell carci-
nomas (RCC) in 398 RT patients (RCC) SIR was
18.19 (CI [Confidence Interval] 4.96-46.57), (p
<0.001). After exclusion of 12 patients from RP
cohort (n:419) in whom the prostate cancer was an
incidental finding during surgery for bladder can-
cer (SIR 33.50 [CI 17.83–57.28]), (p <0.001), 407
patients were observed. There was no synchro-
nous RCC among 325 RP patients who had no
Conclusions: In patients with prostate cancer,
abdominopelvic CT staging detects incidental
second primary cancers (mostly commonly RCC)
with a greater frequency than that expected.
Key words: prostate neoplasms; kidney neoplasms;
incidental cancer; synchronous second primary cancer;
X-ray computerised tomography
In the last two decades prostate cancer diag-
nosis has usually been followed by a pretreatment
staging workup for most patients considered for
radical radiotherapy (RT). Staging recommenda-
tions usually include both radionuclide bone scans
and CT scans of the abdomen and pelvis. Al-
though the sensitivity of both investigations is low
for detection of disease extension to the lymph
nodes or bones, abdominal CT studies can inci-
dentally reveal clinically silent findings such as
cysts, vascular abnormalities or tumours [1, 2].
Discovery of an incidental primary malignancy in
particular often changes patient management.For
example, in many cases the second primary tu-
mour may require treatment more urgently than
the prostatic malignancy,for which therapy would
then be deferred.
The purpose of this report was to document
the power of abdominal CT scan to detect syn-
chronous primary malignancies in prostate cancer
patients undergoing a staging workup before cura-
tive RT, compared with the incidence of second
malignancies in patients undergoing radical pros-
tatectomy (RP), in whom staging workups were
not routinely carried out.
As multiple primary cancers of the urinary tract
are not infrequent [3–5],we hypothesised that most
incidental cancers detected by CT would be con-
fined to the same organ system. Although there are
reports in the literature regarding incidental intra-
during imaging for unrelated health problems [2,3,
6, 7], to our knowledge there are no published data
concerning this aspect of prostate cancer staging.
No conflict of
interest in relation
to this article.
Synchronous primary tumors and prostate cancer
Between 1991 and 2001 at Geneva University Hos-
pital 398 patients (mean age 67 years) treated by curative
RT for prostate cancer underwent a staging workup in-
cluding abdominal CT. Clinical records and those of the
Geneva Tumour Registry (GTR), were reviewed in order
to identify all synchronous primary cancers, characterise
their mode of discovery and document subsequent follow-
up in these patients.The GTR identified a second cohort
of 419 prostate cancer patients (mean age 64 years),
treated in Geneva during the same period by RP,of whom
84 patients also underwent a staging workup including
abdominal CT. All second primary malignancies diag-
nosed within 6 months of the diagnosis of prostate cancer
were obtained from the GTR records.The role of the
staging workup , and of the abdominal CT scan in partic-
ular,was evaluated in each patient in whom a synchronous
tumour was diagnosed. Using the GTR database we cal-
culated standardised incidence ratios (SIR) by dividing
the observed incidence of a specific second malignancy
among prostate cancer patients by the incidence expected
for the same tumour in a population with the same age
Among 398 patients in the RT cohort, 6 inci-
dental second malignancies were detected (1.5%):
four renal-cell carcinomas (RCC), one pancreatic
cancer and one rectal cancer. All 6 malignancies
were detected in asymptomatic patients by CT
scan (398 RT patients and 82 RP patients: 1.2% of
480 patients who had a scan). No further malig-
nancies were discovered 6 months after treatment
of prostate cancer. Table 1 summarises the perti-
nent clinical information for these 6 patients. All
incidental tumours were treated by cu-rative sur-
gery before starting radiotherapy for prostate can-
cer; 4 of 6 patients (66%) are alive and free from
recurrence of the second primary malignancies.
The rate of detection of RCC was significantly in-
creased compared with that expected in the gen-
eral population, with an SIR of 18.19 (CI 4.96–
46.57) (p <0.001).
However, detailed analysis of RP cohort pa-
tients revealed that among 419 patients coded as
having undergone RP,12 were in fact bladder can-
cer cases in whom prostate cancer was diagnosed
incidentally during cystectomy with an SIR of
33.50 (CI 17.83–57.28),(p <0.001).After exclusion
of 12 patients in the RP cohort we observed 407
patients. No synchronous primary cancer was di-
agnosed among 82 patients (20% of 407 patients)
submitted for preoperative CT scanning of the RP
On the other hand, in the analysis of 325 RP
patients without preoperative staging workup,one
primary cancer (bladder cancer) was identified via
cystoscopy motivated by macroscopic persistent
haematuria before RP. But only 20.6% (84 of 407
patients) of the RP cohort underwent cystoscopy.
This finding was therefore considered a purely da-
tabase finding not representative of the whole
and outcome for
the six patients with
after staging workup
for prostate cancer.
Patient Age Prostate cancerSecond cancerFollow-up
cancer at last
Status second cancer
at last follow-up
1 67 cT1cN0M0;
G2; PSA* 3.6
pT3bN0 Renal adenocarcinoma16.17 NED**NED
2 66 cT3aN0M0;
Gleason 5; PSA 13
pT1N0 Ampulla of Vater carcinoma 14.58NEDNED
3 69 cT3aN0M0;
Gleason 6; PSA 29
pT2N0 Renal clear cell carcinoma 13.33NEDNED
Gleason 8; PSA 10
pT3N0 Rectum adenocarcinoma1.08NEDDead liver
Gleason 8; PSA 23
pT3N0 Renal clear cell carcinoma 5.67NEDDead brain metastases
Gleason 6; PSA 33
pT1N0 Renal clear cell carcinoma6.83NED NED
* PSA: Prostate specific antigen; ** NED: No evidence of disease
SWISS MED WKLY 2010;140(15–16):233–236 · www.smw.ch
Incidental asymptomatic renal tumours diag-
nosed by imaging procedures (i.e. abdominal ultra-
sonography,CT and MRI) performed for unrelated
[2, 5, 6]. The increasing use of abdominal imaging
may partly explain the rising incidence of primary
RCC [7–9]. In fact the number of imaging studies
almost doubled between 1986 and 1994 .Thus
the proportion of RCC discovered incidentally has
also risen to 48–66% in recent years, most of them
change in renal cancer presentation (i.e.lower stage
icant impact on the prognosis of patients with or-
tentials . Gudbjartsson et al. concluded that the
increased frequency of incidental detection of RCC
has improved the survival of the patients with RCC
. However, in another report Gimenez et al.
found no drop in the mortality of RCC with the in-
cer patients undergoing abdominal CT staging in
our series were localised and lymph node negative
(N0) tumours.These tumours were all treated sur-
gically with curative intent before addressing the
significant (p <0.001) in view of the 4 RCC patients
for 0.22 expected.
Koyama et al. reported that among multiple
prostate cancer and RCC tend to be discovered in-
cidentally and concomitantly,whereas the diagnosis
of bladder cancer is a rare incidental finding .
Fenton and Weiss calculated a prevalence of sub-
clinical RCC of 0.21% (range 0.11–0.76%) on five
series including 16 174 middle-aged American pa-
tients undergoing CT screening for different be-
nign and malignant (chiefly lung and colon cancer)
diseases . Four RCCs were incidentally discov-
ered among a pooled subgroup of 945 patients
screened for colon cancer (prevalence 0.42%).This
was less than half the prevalence observed in our se-
prostate cancer. One may speculate whether pa-
tients with prostate cancer are at increased risk of
RCC compared to those presenting with other pri-
mary tumours such as lung or colon. Barocas et al.
observed a higher incidence of RCC in men with
that a common aetiological factor is possible, but
also that the results may be explained by detection
bias . Age at screening may also influence the
likelihood of discovering an incidental second ma-
lignancy,with a higher risk for older patients.Thus,
in our cohort of prostate cancer patients treated by
RT (prevalence of incidental RCC 1%), the mean
age was 67 years, older than the above-mentioned
CT-screened colon cancer patients (mean age 64
years), in whom a 0.42% prevalence of incidental
RCC was observed. Similarly, in a cohort of 1520
lung-cancer patients undergoing CT staging (me-
dian age 59 years), the prevalence of subclinical
RCC was correspondingly lower (0.26%) .
The low proportion of abdominal CT (20%)
among the group of patients undergoing RP com-
complete staging workup may not have been rec-
ommended due to the low likelihood of metastases.
Another factor may influence the difference of per-
centage of CT scan between RT and RP groups: in
our study RT patients were all treated in the same
radiation oncology unit with the same staging pro-
tocol,whereas RP patients were treated in different
hospitals or private clinics in Geneva with probably
different staging protocols or habits among urolo-
gists. Obviously the low percentage of CT scan in
the RP group (20%) may not be representative of
the general population.On the other hand,the lack
of synchronous second primary renal cancer in RP
patients without CT scan (325 prostate cancer pa-
group”compared with RT cohort) may be a finding
to support the power of CT scan in detecting syn-
chronous second cancers.
The observed association between bladder and
prostate malignancies among the RP cohort did not
appear to be indicative of a higher prevalence of in-
cidental bladder cancer in prostate cancer patients;
on the contrary,this reflected the incidental discov-
ery of a certain number of asymptomatic prostate
in an older patient population,as has been reported
by others [20–22]. Consequently, to avoid bias in
our findings we excluded 12 bladder cancer patients
at prostatectomy performed for prostate cancer.
tified by cystoscopy motivated by macroscopic per-
sistent haematuria before RP, among 325 patients
without preoperative CT-scan or cystoscopy, was
considered a purely database finding and not repre-
sentative of the whole population.
RT and RP are usually concurrent and alterna-
tive modalities for the management of localised
prostate cancer. Ultrasonography, CT scan, MRI
(magnetic resonance imaging), radionuclide bone
scan and positron emission tomography (PET) are
radiological modalities used – even if not routinely
the physician and of the patient, resectability of the
tumour,risk from anaesthesia,comorbidities or po-
tential toxicities of treatment modalities may influ-
ence the decision for extension of staging workup
and the choice of management [25,26].
Synchronous primary tumors and prostate cancer
Staging workups with abdominal CT and bone
scan are less often performed nowadays because of
the increasing numbers of favourable patients (i.e.
ng/ml and Gleason score below 7) considered for
radical treatment.Although an abdominal CT can-
not be recommended simply on the basis of the po-
tential of screening for second incidental malignan-
cies,in the near future PET with choline or acetate
resonance imaging,or combined PET-CT imaging
may become the usual diagnostic tools for prostate
cancer workup. Osman et al. reported 3 indetermi-
nate renal lesions and one solid renal mass among
250 patients undergoing PET/CT . Improving
the early detection of incidental and potentially se-
the potential benefits of these new technologies [8,
Thus,the increased detection rate of incidental
second malignancies (especially RCC) with abdom-
inal CT in prostate cancer patients represents rele-
vant data requiring more extensive documentation
in subsequent investigations.The clinical relevance
of the higher incidence of renal tumours with pros-
tate cancer may be its influence on treatment strat-
egy. Clinicians should take decisions for the man-
agement of both tumours.In a recent report Mattar
et al. recommended, for incidentally diagnosed
RCC, active surveillance for older patients and
those with competing risks due to medical comor-
bidities, since their risk of early progression due to
growth or metastases appears to be low. Otherwise,
they suggested avoiding active surveillance for
younger and healthier patients until prognostic fac-
tors are better defined .
Abdominopelvic CT as part of the metastatic
staging workup before curative therapy for prostate
cancer detects asymptomatic synchronous second
RCCs with an incidence significantly increased
compared with that expected in the general popula-
tion. In daily practice clinicians should establish in-
dividualised management strategies when diagnos-
ing synchronous prostate and renal cancers.
Orhan Özsoy MD
Division de Radio-oncologie
Hôpitaux Universitaires de Genève
CH-1211 Genève 14
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