Risk of subsequent primary cancer among prostate cancer patients in Bavaria, Germany.

As the prevalence of prostate cancer in Germany is increasing, the issue of subsequent primary cancer (SPC) becomes more relevant. The aim of this study was to estimate the risk and its changes over time of developing SPC among prostate cancer patients compared with the general male population in Bavaria, southern Germany. Utilizing data from the Population-Based Cancer Registry Bavaria, the risk of SPC was evaluated in 59 259 men with prostate cancer diagnosed between 2002 and 2008 who contributed 159 892 person-years. The relative and absolute risk of developing SPC were calculated using the standardized incidence ratio (SIR) and the excess absolute risk. Changes in the risk were examined by plotting the SIR and its 95% confidence interval against time after the diagnosis of prostate cancer. The overall risk of SPC was significantly increased by 14% compared with the general male population. With regard to specific cancer types, a significantly increased risk of SPC was found for the urinary bladder, kidney, pancreas, melanoma of skin, leukemia, myeloma, brain/nervous system, renal pelvis/ureter, thyroid, and the small intestine. The absolute risk of SPC for most cancer types, however, was below 10 cases per 10 000 person-years. A significantly decreased risk of SPC was found in the lung/bronchus and the liver. Although detection bias cannot be excluded as a contributing factor for our results, we recommend continuing follow-up care of prostate cancer patients particularly with respect to SPC of the urinary system as a precaution.