Breast cancer incidence subsequent to surgical reduction of the female breast.

The incidence of breast cancer was determined in 1245 women who were treated surgically for breast hypertrophy in Copenhagen, Denmark, between 1943 and 1971. Breast cancer cases were identified by a linkage to the Danish Cancer Registry. The expected number of breast cancers was estimated from age and calendar-time specific incidence rates in the Danish female population. A total of 18 breast cancers developed compared to 30.28 expected, yielding a relative risk (RR) of 0.59 (95% confidence interval (CI) 0.35-0.94). The greatest risk reduction was observed ten or more years after the plastic surgery operation in women who had 600 g or more of breast tissue removed (RR = 0.27; 95% CI 0.03-0.99). This suggests that the number of potential foci are important for cancer development in the breast.