Chemotherapy use in early stage anal canal squamous cell carcinoma and its impact on long-term overall survival,,

Abstract

Background: The standard of care for non-metastatic squamous cell carcinoma of the anal canal (SCCA) is concurrent chemoradiotherapy. It is postulated that chemotherapy could be omitted for the earliest stages without worsening outcomes.

Methods: We queried the NCDB from 2004-2016 for patients with cT1N0M0 SCCA treated non-operatively with radiation, with and without chemotherapy, and at least two months of follow-up. Of the 2,959 patients meeting eligibility, 92% received chemotherapy (n = 2722) and 8% (n = 237) did not. Most patients were white (n = 2676), female (n = 2019), had private insurance (n = 1507) and were treated in a comprehensive cancer center (n = 1389). Average age was 58.5 years.

Results: Predictors of chemotherapy omission were age > 58 years (OR 0.66, 95% CI [0.49-0.90], P = 0.0087), higher comorbidity score (OR 0.62, 95% CI [0.38-0.99], P = 0.0442), African American race (OR 0.57, 95% CI [0.36-0.90], P = 0.0156) and treatment at the start of the study period (OR 1 for years 2004-2006). HR for single-agent chemotherapy was 0.70 (95% CI [0.50-0.96], P = 0.0288) and 0.48 for multi-agent (95% CI [0.38-0.62], P <0.0001). Overall survival was 86% in those that received chemotherapy vs 65% in those who did not (P <0.0001).

Conclusions: In conclusion, patients with early-stage squamous cell cancer of the anus who are treated with combination chemoradiation continue to demonstrate better overall survival than those who undergo radiotherapy alone.

Keywords: Anal cancer; Chemotherapy; National cancer database; Radiotherapy; Survival.