[Second cancer after starting treatment for prostate cancer]

The subjects for the present study were 270 patients with prostate cancer who underwent initial treatment at our hospital over the 14 years from 1986 to 1999. They were investigated to assess the relationship between their treatment and metachronous tumors. Sixteen patients (5.9%) developed cancer of other organs after starting treatment for prostate cancer. These metachronous tumors included gastric cancer in six patients as well as lung cancer, esophageal cancer, colorectal cancer, liver cancer, renal cancer, bladder cancer, skin cancer, leukemia, and mediastinal adenocarcinoma. Treatment for prostate cancer other than surgery included radiotherapy in eight patients, administration of estramustine phosphate sodium in nine patients, and LH-RH analogues in six patients. The chi-square test showed no significant difference in the incidence of metachronous cancer in relation to the presence/absence of these three therapies. The present study therefore ruled out the possible induction of other tumors by treatment for prostate cancer.