Multiple primary malignancies in patients with anal squamous cell carcinoma

Improvements in early intervention and treatment modalities have led to a 26% decline in cancer death rates in the United States (US) in the past two decades (1). This has resulted in about 15 million cancer survivors alive in the US in 2016, a number expected to rise to 20 million by 2026 (2). However, cancer survivors are predisposed to develop new cancers due to risk factors such as genetic disorders and somatic mutations resulting from prior chemotherapy or radiotherapy (3,4). Cancer survivors are now a significant subset of patients presenting with new cancers, accounting for 17% of new cancer cases in the US. An analysis of 10 high-incidence cancer sites using the Surveillance, Epidemiology, and End Results (SEER) registry showed that 55% of patients with two cancers died of their second primary malignancy (SPM), a greater percentage than patients with only a single primary who died of that cancer (5)