S-1-Based versus Capecitabine-Based Preoperative Chemoradiotherapy in the Treatment of Locally Advanced Rectal Cancer: A Matched-Pair Analysis

OBJECTIVE: The aim of this paper was to compare the efficacy and safety of S-1-based and capecitabine-based preoperative chemoradiotherapy regimens in patients with locally advanced rectal cancer through a retrospective matched-pair analysis. MATERIALS AND METHODS: Between Jan 2010 and Mar 2014, 24 patients with locally advanced rectal cancer who received preoperative radiotherapy concurrently with S-1 were individually matched with 24 contemporary patients with locally advanced rectal cancer who received preoperative radiotherapy concurrently with capecitabine according to clinical stage (as determined by pelvic magnetic resonance imaging and computed tomography) and age (within five years). All these patients performed mesorectal excision 4–8 weeks after the completion of chemoradiotherapy. RESULTS: The tumor volume reduction rates were 55.9±15.1% in the S-1 group and 53.8±16.0% in the capecitabine group (p = 0.619). The overall downstaging, including both T downstaging and N downstaging, occurred in 83.3% of the S-1 group and 70.8% of the capecitabine group (p = 0.508). The significant tumor regression, including regression grade I and II, occurred in 33.3% of S-1 patients and 25.0% of capecitabine patients (p = 0.754). In the two groups, Grade 4 adverse events were not observed and Grade 3 consisted of only two cases of diarrhea, and no patient suffered hematologic adverse event of Grade 2 or higher. However, the incidence of diarrhea (62.5% vs 33.3%, p = 0.014) and hand-foot syndrome (29.2% vs 0%, p = 0.016) were higher in capecitabine group. Other adverse events did not differ significantly between two groups. CONCLUSIONS: The two preoperative chemoradiotherapy regimens were effective and safe for patients of locally advanced rectal cancer, but regimen with S-1 exhibited a lower incidence of adverse events.