Breast cancer and cardiovascular outcomes after breast cancer in survivors of Hodgkin lymphoma

Background Hodgkin lymphoma (HL) survivors treated with chest radiotherapy have an increased risk of breast cancer (BC). Prior HL treatment and associated cardiovascular disease (CVD) risk may limit BC treatment options. It is unknown how treatment adaptations affect BC and CVD outcomes. Methods The authors compared 195 BC patients treated with chest/axillary radiotherapy for HL (BC‐HL) with 5988 age‐ and calendar year‐matched patients with first primary BC (BC‐1). Analyses included cumulative incidence functions and Cox regression models, accounting for tumor characteristics and BC treatment. Results Compared to BC‐1 patients, BC‐HL patients received anthracycline‐containing chemotherapy (23.7% vs. 43.8%, p < .001) and breast‐conserving surgery followed by radiotherapy (7.1% vs. 57.7%, p < .001) less often. BC treatment considerations were reported for 71% of BC‐HL patients. BC‐HL patients had a significantly higher risk of 15‐year overall mortality than BC‐1 patients (61% vs. 23%). Furthermore, risks of BC‐specific mortality and nonfatal BC events were significantly increased among BC‐HL patients, also when accounting for tumor and treatment characteristics (2.2‐ to 4.5‐fold). BC‐HL patients with a screen‐detected BC had a significantly reduced (61%) BC‐specific mortality. One‐third of BC‐HL patients had CVD at BC‐diagnosis, compared to <0.1% of BC‐1 patients. Fifteen‐year CVD‐specific mortality and CVD incidence were significantly higher in BC‐HL patients than in BC‐1 patients (15.2% vs. 0.4% and 40.4% vs. 6.8%, respectively), which was due to HL treatment rather than BC treatment. Conclusions BC‐HL patients experience a higher burden of CVD and worse BC outcomes than BC‐1 patients. Clinicians should be aware of increased CVD risk when selecting BC treatment for HL survivors. Lay summary Patients with breast cancer after Hodgkin lymphoma (BC‐HL) may have limited options for BC treatment, due to earlier HL treatment and an associated increased risk of cardiovascular disease (CVD). BC treatment considerations were reported for 71% of BC‐HL patients. We examined whether BC‐HL patients have a higher risk of CVD or BC events (recurrences/metastases) compared to patients with breast cancer that had no earlier tumors (BC‐1). We observed a higher burden of CVD and worse BC outcomes in HL patients compared to BC‐1 patients. Clinicians should be aware of increased CVD risk when selecting BC treatment for HL survivors.