Objective: To evaluate the overall risk of breast cancer and breast cancer characteristics in women given supradiaphragmatic radiation therapy for Hodgkin lymphoma.
Patients and methods: Medical records of 653 female patients who received supradiaphragmatic radiation therapy for Hodgkin lymphoma at the Mayo Clinic in Rochester, Minn, between 1950 and 1993 were abstracted, and follow-up questionnaires were mailed. In 4 patients, breast cancer was diagnosed before Hodgkin lymphoma was discovered.
Results: The median age of 649 patients at supradiaphragmatic radiation therapy was 31.8 years (range, 2.6-86.5 years). The median duration of follow-up was 8.7 years (range, < 1-47.9 years). In 30 patients, breast cancer developed (bilaterally in 4 patients) after supradiaphragmatic radiation therapy; the median interval was 19.9 years (range, 0.7-423 years). The median age at breast cancer diagnosis was 44.4 years (range, 27.5-70.8 years). The standardized morbidity ratio for breast cancer after supradiaphragmatic radiation therapy was 2.9 (95 % confidence interval [CI], 2.0-4.2) (P < .001). Breast cancer risk significantly increased 15 to 30 years after patients received supradiaphragmatic radiation therapy, and risk was inversely related to age at supradiaphragmatic radiation therapy until age 30 years. The standardized morbidity ratio for patients younger than 30 years at supradiaphragmatic radiation was 8.5 (95% CI, 53-13.1) vs 1.2 (95% CI, 0.5-2.2) for those aged 30 years or older (P < .001). Splenectomy increased breast cancer risk (P = .01). Breast cancer detection was by self-examination in 15 cancers, by mammography in 13, and by clinical examination in 4; in 2 cancers, the mode of detection was unknown. Modified radical mastectomy was used to treat breast cancer.
Conclusion: The increased risk of breast cancer in survivors of Hodgkin lymphoma given supradiaphragmatic radiation therapy appears to be limited to patients who are younger than 30 years at radiation therapy or to those who have undergone splenectomy.