Treatment of Stages I-III Squamous Cell Anal Cancer: A Comparative Effectiveness Systematic Review.

Abstract

To assess the effectiveness and harms of initial treatment strategies for stages I-III anal squamous cell cancer (SCC). We searched Medline®, Embase®, and CENTRAL®, between January 1, 2000- March 2024, for randomized controlled trials and nonrandomized studies of interventions comparing initial treatment strategies. Individual study risk of bias (RoB) and overall strength of evidence (SOE) were evaluated for a prespecified outcome list using standardized methods. We identified 33 eligible studies and extracted data. Six were deemed low/moderate RoB. Compared with radiotherapy (RT) alone, chemoradiotherapy (CRT) with 5-fluorouracil (FU) and mitomycin C (MMC) probably shows a benefit in locoregional failure (LRF), disease-specific (DSS), and colostomy-free survival (CFS) (moderate SOE) yet may result in greater overall and acute hematologic toxicity, with no difference in late harms (low SOE). CRT with 5FU+MMC may show a benefit in LRF, DSS, and CFS rates compared with 5FU alone (low SOE). CRT with 5FU+cisplatin vs 5FU+MMC probably results in no differences in several effectiveness outcomes or overall acute or late harms, and probably increases hematologic toxicity with MMC (moderate SOE). Compared with CRT using capecitabine+MMC, CRT with capecitabine+MMC+paclitaxel may improve OS, DSS, and CFS, yet cause more acute harms (low SOE). Evidence was insufficient for remaining comparisons. CRT with 5FU+MMC or 5FU+cisplatin is likely more effective yet incurs greater acute hematologic toxicity than RT alone or single-agent CRT. Adding paclitaxel to capecitabine+MMC may increase treatment efficacy and toxicity. Evidence is insufficient comparing post-treatment surveillance strategies and patient-reported outcomes, highlighting research opportunities.