[Multiple primary malignant tumors after radical mastectomy].
Second primary malignancy experience was examined for 2,427 primary breast cancer during 1964-1982. There were 72 cases observed which developed a second malignancy after the treatment of antecedent breast cancer. Annual accumulated incidences of double cancer regressed on a linear equation of Y = 0.43X + 0.36, and expected incidence for 5 years was 2.5%, for 10 years 4.7% and for 15 years 6.8%, respectively. Calculating the expected cancer morbidity in person-years method, we found that the observed incidence of double cancer was higher than that expected; the ratio of O/E was 1.40. The opposite brest cancer was mainly responsible for this higher risk (O/E ratio was 6.37). Also the higher risks were pointed out for cancer of uterine corpus and ovary. MMC and CPA was given as surgical adjuvants for one third of the patients. The results analysed by person-years method showed there were no increased incidences of second malignancy in chemotherapy groups compared with the control group.