Multiple primary cancers (MPC) associated with bladder cancer: an analysis of the clinical and autopsy cases in Japan.

Three hundred seventy-two clinical cases of multiple primary cancers (MPCs) involving bladder cancer (reported in the Japanese literature and including 36 of our own cases) and 376 autopsy cases (collected from the tables of the Annuals of Pathological Autopsy Cases in Japan from 1974 to 1981), were analyzed. Of the clinical cases studied, 299 patients were males and 73 females, and their average age was 65.7 years. In the 342 cases having only two primary cancers (PC), the two most common cancers associated with bladder cancer were cancer of the stomach (27.4%) and of the prostate (15.3%) in the males, and cancer of the cervix (27.9%) and of the stomach (16.2%) in the females. In the 119 cases in which the interval was known, the two PC were synchronous in 58 cases and metachronous in 61. In most cases of bladder cancer associated with other urological cancers (85.2%) the two were synchronous. In the females with metachronous cancers, bladder cancer frequently occurred as the second cancer after treatment of cervical or breast cancer. In autopsy cases, the ratio of MPC cases to the total number of cancer cases was 5.2%, and the ratios of MPC cases including bladder cancer to the total number of MPC cases and bladder cancer cases were 5.7% and 15.9%, respectively. The results of a study on organ association between cancer of the urinary bladder and of other organs were almost the same as those in the clinical study except for a lower frequency in other urogenital organs. In an epidemiological analysis of our own cases, the risk of MPC associated with bladder cancer was found to be highest in the stomach, the prostate, the larynx, and the liver. A significant value for the relative risk of a second cancer in another organ following bladder cancer was observed only for the prostate.