Radiotherapy alone versus chemoradiotherapy for stage I anal squamous cell carcinoma: a systematic review and meta-analysis

Purpose Patients with stage I anal squamous cell carcinoma (SCC) have been underrepresented in landmark trials showing superiority of chemoradiotherapy over radiotherapy for definitive treatment. This review aims to elucidate whether definitive treatment with radiotherapy versus chemoradiotherapy is associated with differences in survival and treatment-related toxicity outcomes in patients with stage I anal SCC. Methods Medline, EMBASE, and CENTRAL were searched as of November 2020 to identify studies comparing outcomes of radiotherapy versus chemoradiotherapy for non-operative treatment of patients with stage I anal SCC. The primary outcomes were 5-year overall survival and 5-year disease-free survival. The secondary outcome was treatment-related toxicities. A pairwise meta-analysis was performed using an inverse-variance random-effects model. Results From 2174 citations, 5 retrospective studies with 415 patients treated with radiotherapy and 3784 patients treated with chemoradiotherapy were included. Patients treated with chemoradiotherapy had an increased 5-year overall survival (RR 1.18, 95% CI 1.10–1.26, p