Elevated risk of human papillomavirus-related second cancers in survivors of anal canal cancer.

Abstract

Over the last decade, the causal link between human papillomavirus (HPV) infection and squamous cell carcinoma of the anus (SCCA) has been well described. Because HPV infection in one site is often associated with other sites of infection, it then follows that patients with SCCA may have an increased risk of additional HPV-related cancers. Identifying and targeting at-risk sites through cancer screening and surveillance may help to guide best practices. The current study sought to ascertain sites and risk of HPV-related second primary malignancies (SPMs) in survivors of SCCA. Using population-based data from 1992 through 2012, the authors identified patients with SCCA and determined their risk of HPV-related SPMs, including anal, oral, and genital cancers. Standardized incidence ratios (SIRs), defined as observed to expected cases, were calculated to determine excess risk. Of 10,537 patients with SCCA, 416 developed HPV-related SPMs, which corresponded to an overall SIR of 21.5 (99% confidence interval [99% CI], 19.0-24.2). Men were found to have a higher SIR (35.8; 99% CI, 30.7-41.6) compared with women (12.8; 99% CI, 10.4-15.5). SIRs for a second SCCA were markedly higher in men (127.5; 99% CI, 108.1-149.2) compared with women (47.0; 99% CI, 34.7-62.1), whereas SIRs for oral cavity and pharyngeal cancers were elevated in men (3.1; 99% CI, 1.5-5.7) and women (4.4; 99% CI, 1.5-9.7). SIRs for sex-specific sites also were elevated, with male genital cancers having an SIR of 19.6 (99% CI, 8.7-37.6) and female genital cancers an SIR of 8.3 (99% CI, 6.1-11.0). Patients with index SCCA are at an increased risk of subsequent HPV-related SPMs. The elevated risk is most striking in patients with second primary SCCAs; however, the risk of second cancers also appears to be increased in other HPV-related sites. Cancer 2017;123:4013-21. © 2017 American Cancer Society.