Risk for Second Cancer Low for Women Treated for Early, Invasive Breast Cancer

THURSDAY, Sept. 4, 2025 (HealthDay News) -- The risk for second primary cancers is higher for breast cancer survivors than for women in the general population; however, the risk remains low and is mostly driven by contralateral breast cancer, according to a study published online Aug. 27 in The BMJ.Paul McGale, Ph.D., from the University of Oxford in the United Kingdom, and colleagues conducted an observational cohort study to assess long-term risks for second nonbreast primary cancers and contralateral breast cancers among women with early invasive breast cancer who underwent primary surgery. The analysis included data from the National Cancer Registration and Analysis Service for England on 476,373 women with breast cancer as their first invasive (index) cancer (1993 through 2016).The researchers found that by 20 years, 13.6 percent of women developed a nonbreast cancer -- 2.1 percent more than expected in the general population -- while 5.6 percent developed a contralateral breast cancer, which was 3.1 percent more than expected. In younger women, the absolute excess risk for contralateral breast cancer was greater than in older women. The largest 20-year absolute excess risks for nonbreast cancer were for uterine and lung cancers. While the standardized incidence ratios exceeded those of the general population by a factor of at least 1.5 for cancers of the uterus, soft tissue, bones and joints, and salivary glands, as well as acute leukemias, absolute excess risks at 20 years were <1 percent for every individual nonbreast cancer type. Radiotherapy was associated with increased contralateral breast and lung cancer, endocrine therapy with increased uterine cancer, and chemotherapy with increased acute leukemia. Roughly 2 percent of all the 64,747 second cancers and 7 percent of the 15,813 excess second cancers in the cohort may be attributable to adjuvant therapies. "Many breast cancer survivors believe their risks of a second cancer are much higher than those we estimated," the authors write. "The information in our study can reassure them and help them to plan their future."Abstract/Full TextEditorial (subscription or payment may be required).Sign up for our weekly HealthDay newsletter