Yanru Feng¹, Jing Jin², Hua Ren², Xin Wang², Shulian Wang², Weihu Wang², Yongwen Song², Yueping Liu², Yuan Tang², Ning Li², Xinfan Liu², Hui Fang², Zihao Yu², Yexiong Li²

¹Department of Radiation Oncology,Cancer Hospital & Institute, Chinese Acadamy of Medical Sciences, Pekingunion   Medical College, ²Chinese Acadamy ofMedical Sciences, Cancer Hospital & Institute

Objective:To evaluate radiochemotherapeutic sequencefor pathological stage N2 rectal cancer in the era of oxaliplatin-basedadjuvant therapy. Method: Treatment outcomes and impact of differentsequence of adjuvant concurrent radiochemotherapy and chemotherapy for stage N2rectal cancer patients after curative surgery were analyzed and compared. Inthe primary adjuvant concurrent chemoradiotherapy (A-CRT) group (N=71),postoperative CRT was administered before adjuvant chemotherapy. In the primaryadjuvant chemotherapy (A-CT) group (N=43), postoperative CRT was administeredduring or after adjuvant chemotherapy. Postoperative radiotherapy consisted of45-50.4 Gy in 25-28 fractions. Concurrent chemotherapy comprised two cycles oforal capecitabine (1,600 mg/m²) on days 1–14 and 22–35. Patientsreceiving adjuvant chemotherapy≥4 cycles of CapeOX or≥8 cycles of FOLFOX wereincluded. Result: Between June 2005 and December 2013, 114 qualifiedrectal cancer patients were analyzed. 33.8% of patients in the A-CRT group and16.3% of patients in the A-CT group developed treatment failure (P=0.042). More patients had distantmetastasis in the A-CRT group compared with those in the A-CT group (32.4% vs.14.3%, P=0.028). No statisticallysignificant difference was observed in 3-year estimated disease-free survivalbetween the primary A-CRT and the A-CT groups. Multivariate analysis indicatedthat radiochemotherapeutic sequence (Primary A-CT vs. Primary A-CRT) wasidentified as an independent prognostic factor for both estimated disease-freesurvival (HR0.345, 95%CI .137-.868, P=0.024)and estimated distant metastases free survival (HR0.366, 95%CI 0.143-0.938, P=0.036). Conclusion: Forpathological stage N2 rectal cancer patients, receiving adjuvant chemotherapybefore chemoradiation showed lower treatment failure, especially distantmetastasis. Adjuvant chemotherapy prescribed as earlier as possible mightbenefit this cohort of patients in the era of oxaliplatin-based adjuvanttherapy.

KeyWords: Adjuvant chemoradiotherapy  Sequence Rectal cancer