At present, distant metastasis remains the main cause of failure for locally advanced rectal cancer (LARC), efficient short-course radiotherapy (SCRT) combined with neoadjuvant chemotherapy is an attempt of optimizing pre-operative treatment.
We did this randomized, phase III study in multiple centers in China. Patients with middle or lower rectal adenocarcinomas, staged cT3-4 and/or N1-2 by MRI, were randomly assigned to receive 5Gy × 5 and 4 courses of CAPOX (experimental group) or 50 Gy in 25 fractions concurrently with capecitabine (control group). TME in both groups was performed 6-8 weeks later, then two or six courses of CAPOX as postoperative chemotherapy was prescribed in experimental or control group, respectively. The purpose of this interim analysis was focusing on the compararison of primary enrolled 100 patients.
Initially enrolled 100 patients, 51 in experimental group and 49 in control group were analyzed, with MRF+ 27.5% vs. 30.6%, MRI based T3-4 92.2% vs. 98.0%, N1-2 74.5% vs. 77.6%, and EMVI scores3-4 52.9% vs. 65.3% in each group. The completion rates of neoadjuvant treatment were 98.0% vs. 100% (p = 0.325), with incidences of grade III-IV toxicity 17.6% vs. 4.1% (p = 0.076) in each group, respectively. 80 patients completed surgery and 7 patients (all in experimental group) chose “watch-and-wait” policy due to clinical complete remission (cCR) after neoadjuvant treatment. 92.9% and 89.5% of patients in experimental and control group had R0 resection (p = 0.593), while 26.2% and 5.3% of them achieved ypT0N0 (p = 0.011), respectively. The completion rates of adjuvant chemotherapy were 76.2% vs. 65.8% (p = 0.305) in each group, respectively. On the whole, the patients who had received 6 cycles of chemotherapy accounted for 62.7% vs. 49.0% (p = 0.000) in experimental and control group, and there were 76.5% and 49.0% of patients who could complete all planned treatments in each group, respectively.
The interim analysis revealed the acute toxicity and surgical complication were acceptable and comparable in both groups, however, the people in experimental group showed better treatment completion.
Clinical trial identification
Legal entity responsible for the study
National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College.
Collaborative Innovation Center for Cancer Medicine [No. XT2015-03].
All authors have declared no conflicts of interest.