Purpose: Squamous cell cancer (SCC) is a rare histological subtype of rectal cancer. It is unclear whether SCC should be treated by multimodal therapy, including surgery, or by chemoradiation alone. The objective of the study was to define an optimal treatment strategy.
Methods: Patients with rectal cancer and SCC histology were identified in the Surveillance Epidemiology and End Results Database between 1990 and 2013. According to treatment, three groups were defined: radiotherapy and surgery (RT/SX), radiotherapy (RT), and surgery (SX). Overall survival (OS) and disease-specific survival (DSS) for localized, regional, and distant disease were assessed using a multivariable Cox regression model.
Results: Out of 856,435 colorectal cancer patients, 1747 with SCC of the rectum were eligible. Four hundred and fifty-five were treated with RT/SX, 994 with RT, and 298 with SX. Adjusted hazard ratios (HR) did not differ for OS and DSS in localized disease. In regional disease, OS and DSS were improved for RT/SX compared to RT (HR 0.751, 95% CI 0.566-0.997, P = 0.048 and HR 0.679, 95% CI 0.478-0.966, P = 0.031). In distant disease, OS and DSS were not different.
Conclusions: Multimodal therapy including surgery improved OS and DSS compared to receiving a treatment without surgery for regional disease in rectal SCC. No difference was observed in localized and distant disease. The findings contradict with recent reports favoring definitive chemoradiation.
Keywords: Multimodal treatment; Rectal cancer; Squamous cell cancer; Survival.