[Influence of family history, irradiation and anti-cancer drug (mitomycin C) on the occurrence of multiple primary neoplasms in breast carcinoma patients].

The influence of family history, irradiation and anti-cancer drug (Mitomycin C) on the occurrence of multiple primary neoplasms was analysed using the person-year method in 1359 Japanese breast carcinoma patients. There were 111 multiple primary neoplasms, including bilateral breast cancer, in 109 patients; the incidence rate was 0.0072 per person-year. The incidence rate in patients with a family history of cancer was 1.29 times higher than in those without. In the bilateral breast cancer group there was about a 3 times higher frequency of family history of breast cancer. Irradiation therapy raised the occurrence of multiple primary neoplasms 1.28 fold, and Mitomycin C (40 mg) had no effect on the occurrence of neoplasms during a 10-year observation period.