Intensity-modulated radiation therapy versus 3D conformal radiation therapy for squamous cell carcinoma of the anal canal.

494 Background: The emergence of intensity-modulated radiation therapy (IMRT) in the treatment of anal cancer has dramatically lowered the incidence of severe toxicity while maintaining excellent long-term outcomes. We compared our institutional experience using 3D conformal radiation therapy (3DCRT) versus IMRT for anal cancer. Methods: We performed a single-institution retrospective review of all non-metastatic squamous cell carcinoma anal cancer patients treated between 2000-2011 using definitive chemoradiation with curative intent. Results: This study included 89 consecutive anal cancer patients (37 3DCRT, 52 IMRT). Median follow-up for all patients, IMRT patients alone, and CRT patients alone was 26.5 months (range, 3.5-133.6), 20 months (range, 3.5-125.5), and 61.9 months (range, 7.6-133.6), respectively. Three-year overall survival (OS), progression free survival (PFS), locoregional control (LRC), and colostomy free survival (CFS) were 91.1%, 82.3%, 90.8%, and 91.3% in the IMRT cohort and 86.1%, 72...