Contralateral breast carcinoma: an assessment of risk and prognosis in stage I (T1N0M0) and stage II (T1N1M0) patients with 20-year follow-up.

Among 644 patients with a small (T1) primary breast carcinoma who were followed up for a median of 18.2 years, subsequent contralateral breast carcinomas were detected in 57 of 610 women (9%) who had a contralateral breast at risk. The average annual hazard rate for contralateral carcinomas was 8/1000 patients at risk per year without significant fluctuations throughout the 20 years of follow-up. Recurrences were caused by 9 of 57 (16%) subsequent contralateral carcinomas, and 4 of the 57 patients (7%) died of recurrent contralateral carcinomas. Contralateral carcinomas were responsible for 5.1% (9 of 176) of all recurrences of breast carcinomas and 2.6% (4 of 153) of breast carcinoma deaths. Surveillance of the contralateral breast must continue throughout a patient's lifetime. Detection and treatment of subsequent lesions at an early stage is a beneficial result of follow-up, especially in women whose first carcinoma is likely to have been cured.