Squamous Cancers of the Rectum Demonstrate Poorer Survival and Increased Need for Salvage Surgery Compared With Squamous Cancers of the Anus

BACKGROUND:Squamous cell cancers of the anus are rare GI malignancies for which neoadjuvant chemoradiation is the first-line treatment for nonmetastatic disease. Squamous cancers of the rectum are far less common, and it is unclear to what degree chemoradiotherapy improves their outcomes. OBJECTIVE:The purpose of this study was to compare stage-specific survival for anal and rectal squamous cancers stratified by treatment approach. DESIGN:This was a retrospective cohort study. SETTINGS:The study was conducted at Commission on Cancer designated hospitals. PATIENTS:Patients (2006–2012) identified in the National Cancer Database with pretreatment clinical stage I to III cancers who underwent chemoradiotherapy, with and without subsequent salvage surgical resection (low anterior resection or abdominoperineal resection), ≥12 weeks after chemoradiotherapy were included in the study. MAIN OUTCOME MEASURES:Overall survival and the need for salvage surgery were measured. RESULTS:Anal cancers (n = 11,224) typically presented with stage II (45.7%) or III (36.3%) disease, whereas rectal cancer stages (n = 1049) were more evenly distributed (p < 0.001). More patients with rectal cancer underwent low anterior or abdominoperineal resections 12 weeks or later after chemoradiotherapy versus those undergoing abdominoperineal resection for anal cancer (3.8% versus 1.2%; p < 0.001). Stage I and II rectal cancer was associated with poorer survival compared with anal cancer (stage I, p = 0.017; stage II, p < 0.001); survival was similar for stage III disease. Salvage surgery for anal cancer was associated with worse survival for stage I to III cancers; salvage surgery did not significantly affect survival for rectal cancer. LIMITATIONS:This was a retrospective study without cancer-specific survival measures. CONCLUSIONS:Squamous rectal cancers are associated with significantly worse survival than squamous cancers of the anus for clinical stage I and II disease. Despite both cancers exhibiting squamous histology, rectal cancers may be less radiosensitive than anal cancers, as suggested by the greater incidence of salvage surgery that does not appear to significantly improve overall survival. See Video Abstract at http://links.lww.com/DCR/A422.