MULTIPLE PRIMARY MALIGNANT NEOPLASMS ASSOCIATED WITH PROSTATE-CANCER IN 312 CONSECUTIVE CASES

The relative risk for a second primary cancer after the diagnosis of p rostate cancer and the prognostic impact of the association of multipl e primary malignant neoplasms (MPMNs) in patients with prostate cancer were analyzed in a retrospective study. The development of MPMNs was examined in 312 consecutive patients who had been diagnosed with prost ate cancer between 1966 and 1992. The population-based cancer incidenc e rates in Japan were utilized to calculate the expected number of MPM Ns. Of the 312 patients, 60 fulfilled the diagnosis of MPMNs. In 13 me n, prostate cancer and other malignancies were diagnosed simultaneousl y. In 35 of the 312 patients, prostate cancer was the second or third cancer diagnosis. In the remaining 287 patients, prostate cancer devel oped initially. Of the 287 patients, 12 developed a second primary mal ignancy compared with 17 expected (relative risk 0.71, 95% confidence interval 0.45-1.4). No single anatomic site showed a significantly inc reased risk above that expected either. The overall survival of patien ts with prostate cancer was not reduced by the association with MPMNs. This may be explained by the fact that the stage of the prostate canc er was lower in patients with MPMNs than in patients without MPMNs.