Risk of prostate cancer among cancer survivors in the Netherlands

Background: In parallel with increasing numbers of cancer patients and improving cancer survival, the occurrence of second primary cancers becomes a relevant issue. The aim of our study was to evaluate risk of prostate cancer as second primary cancer in a population-based setting.

Methods: Data from the Netherlands Cancer Registry were used to estimate standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for prostate cancer as second primary cancer. The effect of time since first cancer diagnosis, specific first cancer sites, age, and pelvic radiotherapy was taken into account.

Results: Out of 551,553 male patients diagnosed with a first primary cancer between 1989 and 2008, 9243 patients were subsequently diagnosed with prostate cancer. Overall, cancer survivors showed an increased risk (SIR 1.3, 95% CI 1.2-1.3) of prostate cancer. The increased prostate cancer risk was limited to the first year of follow-up for the majority of the specific first cancer sites. More than 10 years after the first cancer diagnosis, only melanoma patients were at increased risk (SIR 1.5, 95% CI 1.2-1.9), while patients with head or neck cancers were at decreased risk (SIR 0.7, 95% CI 0.5-0.9) of being diagnosed with prostate cancer. Patients who underwent primary pelvic radiotherapy for their first cancer had a decreased risk of prostate cancer in the long term (SIR 0.5, 95% CI 0.4-0.6).

Conclusions: Our data showed that cancer survivors have an increased prostate cancer risk in the first year following a first cancer diagnosis, which is most likely the result of active screening or incidental detection.