Risks of second non-breast primaries following breast cancer in women: systematic review and meta-analysis

A systematic review and meta-analysis of one prospective and twenty-seven retrospective studies analyzed the risks of second non-breast primaries following breast cancer in women. The standardized incidence ratios for second non-breast primaries combined ranged from 0.84 to 1.84, with a summary SIR estimate of 1.24 (95% CI 1.14-1.36; I²=99). The estimate was higher in women with breast cancer diagnosed before age 50 versus age 50 and over, and in women in Asia versus women in Europe. There were significantly increased risks of second thyroid, corpus uteri, ovary, kidney, esophagus, melanoma, leukemia, lung, stomach, and bladder primaries.