Higher than expected association of clinical prostate and bladder cancers

In this study we evaluated the risk of a second malignancy of the bladder or prostate in patients with a previous diagnosis of prostate cancer (PCa) or urothelial cancer (TCC).

We retrospectively analyzed all cases of PCa and TCC diagnosed between January 1996 and June 2003. Only PCa diagnosed due to abnormal digital rectal examination or increased prostate specific antigen were included. All patients with TCC presented with hematuria or irritative voiding symptoms and the diagnoses were confirmed with a tissue diagnosis. The incidence of lung, colon and renal cancers was also analyzed.

A total of 816 men were diagnosed with PCa and/or TCC. Of 673 men initially diagnosed with PCa 21 had TCC. Of 149 men initially diagnosed with TCC 18 had PCa. Average age at PCa and TCC diagnosis +/- SD was 68.2 +/- 7.9 and 68.2 +/- 10.4 years, respectively. The standardized incidence ratio (SIR) of TCC in patients with PCa (SIR 4.31, 95% CI 2.411 to 7.110) and of PCa in patients with TCC (SIR 3.83, 95% CI 1.911 to 6.858) was significantly increased. There was no statistical significant difference in SIR for TCC in men with or without radiotherapy. SIR for lung, renal or colon cancer was not significantly different from what was expected.

Patients with PCa have higher incidence of bladder cancer and those with bladder cancer have a higher incidence of PCa. This study has clinical implications in the care of these patients and it may stimulate research interest that may identify common pathways of carcinogenesis.