Comparison of concurrent chemoradiotherapy with capecitabine and oxaliplatin versus capecitabine alone in stage II/III rectal cancer patients after radical operation

Objective To compare the efficacy of concurrent chemoradiotherapy (CCRT) with capecitabine and oxaliplatin versus capecitabine alone in stage Ⅱ/Ⅲ rectal cancer patients after radical operation.Methods A retrospective analysis was performed on the clinical data of 675 patients with stage Ⅱ/Ⅲ rectal cancer who received postoperative concurrent chemoradiotherapy (CCRT) with capecitabine (CAP group,n =427) or capecitabine and oxaliplatin (CAPOX group,n =248) from 2002 to 2010.The treatment modality was total mesorectal excision + CCRT ± adjuvant chemotherapy.Radiotherapy was delivered to the true pelvis at a dose of 45.0-50.4 Gy/25 fractions.Results The propensity score matching method (1 ∶ 1) was applied to balance the baseline characteristics and assign 248 patients to each group.The 5-year sample sizes for CAP group and CAPOX group were 81,104.There were no significant differences between the two groups in 5-year overall survival (78.1％ vs.74.9％,P =0.547),disease-free survival (74.4％ vs.67.9％,P =0.292),locoregional control (94.5％ vs.92.8％,P =0.484),and distant metastasis-free survival (77.1％ vs.70.9％,P =0.364).But grade 3/4 toxicities occurred in 24.6％ of patients in the CAP group,versus 38.3％ in the CAPOX group (P =0.001).Conclusions CCRT with oxaliplatin and capecitabine has no survival advantage over CCRT with capecitabine alone and increases the incidence of toxicities in stage Ⅱ/Ⅲ rectal cancer patients after radical operation.CCRT with capecitabine alone is still the standard regimen. Key words: Rectal neoplasms/surgery; Surgery, total mesorectal excision; Rectal neoplasms/radiochemotherapy; Chemotherapy, capecitabine, oxaliplatin