Breast Cancer in Female Survivors of Wilms Tumor: A Report From the National Wilms Tumor Late Effects Study

BACKGROUNDThe standard treatment of pulmonary metastases in patients with Wilms tumor (WT) includes 12-gray radiotherapy (RT) to the entire chest. To the authors' knowledge, the risk of breast cancer (BC) in a large cohort of female survivors of WT has not previously been reported. METHODSA total of 2492 female participants in National Wilms Tumor Studies 1 through 4 (1969-1995) were followed from age 15 years through the middle of 2013 for incident BC. The median age at the time of last contact was 27.3 years. The authors calculated cumulative risk at age 40 years (CR40), hazard ratios (HR) by Cox regression, standardized incidence ratios (SIRs) relative to US population rates, and 95% confidence intervals (95% CIs). RESULTSThe numbers of survivors with invasive BC divided by the numbers at risk were 16 of 369 (CR40, 14.8% [95% CI, 8.7-24.5]) for women who received chest RT for metastatic WT, 10 of 894 (CR40, 3.1% [95% CI, 1.3-7.41]) for those who received only abdominal RT, and 2 of 1229 (CR40, 0.3% [95% CI, 0.0-2.3]) for those who received no RT. The SIRs for these 3 groups were 27.6 (95% CI, 16.1-44.2) based on 5010 person-years (PY) of follow-up, 6.0 (95% CI, 2.9-11.0) based on 13,185 PY of follow-up, and 2.2 (95% CI, 0.3-7.8) based on 13,560 PY of follow-up, respectively. The risk was high regardless of the use of chest RT among women diagnosed with WT at age 10 years, with 9 of 90 women developing BC (CR40, 13.5% [95% CI, 5.6-30.6]; SIR, 23.6 [95% CI, 10.8-44.8] [PY, 1463]). CONCLUSIONSFemale survivors of WT who were treated with chest RT had a high risk of developing early BC, with nearly 15% developing invasive disease by age 40 years. Current guidelines that recommend screening only those survivors who received 20 Gy of RT to the chest might be reevaluated. Cancer 2014;120:3722-3730. (c) 2014 American Cancer Society. Female survivors of Wilms tumor treated with chest irradiation for pulmonary metastasis had a 15% risk of invasive breast cancer by age 40 and breast cancer rates 28 times higher than for the general population. Those who received only abdominal irradiation had a 3% risk and rates 6 fold higher than background.