[Value of postoperative adjuvant chemotherapy in locally advanced rectal cancer patients with ypT1-4N0 after neo-adjuvant chemoradiotherapy].

Objective The purpose of this study was to investigate the value of postoperative chemotherapy for locally advanced rectal cancer patients who reached pathological ypT1-4N0 after neoadjuvant chemoradiotherapy.Methods We performed a retrospective study of 104 patients treated with preoperative chemoradiotherapy followed by radical resection,who achieved pathological ypT1-4N0,between Mar 2003 and Dec 2010.There were 73 patients who received postoperative adjuvant chemotherapy,and the other 31 patients did not.The distribution of final pathologic stages for these patients was ypT1-2N0 in 39 cases and ypT3-4N0 in 65 cases.Results The median follow-up was 41 months.The 3-year overall survival rate (OS) and recurrence-free survival rate (RFS) for the whole group (ypT1-4N0) were 93.4％and 85.3％,respectively.The 3-year OS and RFS in the adjuvant chemotherapy group and non-adjuvant chemotherapy group were 95.5％,88.6％ and 88.6％,77.2％,respectively.There were no significant differences in 3-year RFS (P =0.108) and OS (P =0.106) between the two groups.The 3-year local recurrence and distant metastasis rates in the adjuvant chemotherapy group were 4.1％ (3/73)and 5.5％ (4/73),while for the non-adjuvant chemotherapy group,the 3-year local recurrence rate and distant metastasis rate were 3.2％ (1/31) and 16.1％ (5/31),respectively.Significant difference was found in distant metastasis rates (P =0.030)between the two groups,but not in local recurrence rates(P =0.676).Further subgroup analysis indicated that for the ypT1-2N0 patients,there were no significant differences in 3-year OS (P =0.296) and RFS (P =0.939) between the adjuvant and non-adjuvant chemotherapy groups,while negative results displayed in 3-year local recurrence rates (P =0.676) and distant metastasis rates (P =0.414).However,for patients with ypT3-4N0,significant differences were showed in both the 3-year OS (P =0.034) and RFS (P =0.025),and further analysis revealed that the 3-year distant metastasis rate was significantly higher in the non-adjuvant chemotherapy group than in the adjuvant chemotherapy group (P =0.010),but with non-significant difference in the 3-year local recurrence (P =0.548).Conclusions Adjuvant chemotherapy may not improve survival for ypT1-2N0 patients.However,it may be clinically meaningful for ypT3-4N0 patients by decreasing distant metastasis rate.Further randomized controlled clinical trials are needed to confirm our results. Key words: Rectal neoplasms ;  Neoplasm staging;  Neoadjuvant chemoradiotherapy ; Adjuvant chemotherapy;  Prognosis