Background: Several large datasets have shown a reduced risk of all neoplasms after a diagnosis of prostate carcinoma but an increased incidence rate of urologic carcinoma has been suggested.
Methods: Data collected by the Cancer Registries of the Swiss Cantons of Vaud and Neuchâtel (approximately 760,000 inhabitants) were used to estimate the incidence rate of a second primary tumor after a diagnosis of prostate carcinoma. A total of 4503 cases registered between 1974 and 1994 were followed until the end of 1996 (17,065 person-years).
Results: A total of 380 second primary neoplasms were observed versus 534.1 expected primary neoplasms (standardized incidence ratio [SIR] = 0.7; 95% confidence interval, 0.6-0.8). SIRs were significantly below unity for lung carcinoma (SIR = 0.7) and other major tobacco-related neoplasms, including those of the mouth or pharynx (SIR = 0.5), esophagus (SIR = 0.4), pancreas (SIR = 0.5), and larynx (SIR = 0.8). There was no excess rate of subsequent urologic carcinoma (SIR = 1.0) or colorectal carcinoma (SIR = 0.9). The reduced SIRs for lung carcinoma were stronger in elderly men (age >/= 75 years) and in patients with a shorter period since diagnosis (< 5 years).
Conclusions: The incidence of all neoplasms was reduced significantly in men diagnosed with prostate carcinoma. Selection of the population, under-registration of second primary tumors, and reduced surveillance in elderly men with prostate carcinoma may, at least in part, explain this reduction in risk. No excess risk was observed for the complex of urologic neoplasms nor for tobacco-related neoplasms. This finding would not support an association between cigarette smoking and prostate carcinoma.
Copyright 1999 American Cancer Society.