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

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.

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.

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).

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.