SEER database analysis of incidence of nonkeratinocyte skin cancer after breast cancer radiation therapy

Previous studies have suggested that radiation therapy may contribute to an increased risk of subsequent nonkeratinocyte (ie, not squamous and basal cell) skin cancers. A cohort study using data from the SEER database included 875,880 patients with newly diagnosed breast cancer from 2000 to 2019. Among these patients 3839 (0.44%) were diagnosed with nonkeratinocyte skin cancer, including melanoma, Merkel cell carcinoma, hemangiosarcoma and other nonkeratinocyte skin cancers. Radiation therapy for breast cancer was associated with 57% higher risk of nonkeratinocyte skin cancer compared with the general population. Receipt of radiation therapy was associated with a greater risk of nonkeratinocyte skin cancer compared with chemotherapy and surgical interventions. The authors conclude that although nonkeratinocyte skin cancer is a rare occurrence, physicians caring for patients with breast cancer should be aware of this elevated risk to help inform follow-up care for survivors.