Neoadjuvant chemotherapy (CAPOX) alone for low- and intermediate-risk stage II/III rectal cancer: Long-term follow-up of a prospective single-arm study

Background: Stratified treatment has been recommended for rectal cancer. Our previous multicenter randomized trial showed that low-/intermediate-risk rectal cancer patients did not benefit much from neoadjuvant chemoradiotherapy. In our phase II study, we found that stage II/III rectal cancer patients with low-/intermediate risks can be managed by neoadjuvant chemotherapy alone and achieve a good response. The current study aimed to report the long-term survival outcomes in the expanded phase II trial. Method: Consecutive patients diagnosed with mid-low stage II/III rectal cancer with low/intermediate risk factors were included. Four cycles of neoadjuvant chemotherapy (CAPOX) were given, and MRI was used for tumour response detection. The primary endpoint was disease-free survival. The secondary endpoints were tumour response to NCT, tumour-related death, and overall survival. Results: This study enrolled 121 eligible patients. The good tumour response rate based on MRI was 82.6 %, with a pathological complete response (pCR) rate of 18.3 %. The disease-free survival rate was 82.6 %, and the overall survival rate was 96.7 % after a median follow-up time of 40 months. Two patients (1.7 %) suffered local recurrence, and 15 patients (12.4 %) suffered distant metastasis. The median disease-free survival and overall survival were 37 (9-60) and 40 (16-60) months, respectively. Tumour longitudinal length reduction and tumour regression grade on MRI were identified as predictors for poor tumour response to neoadjuvant chemotherapy. Conclusion: In stage II/III rectal cancer patients with low-/intermediate risks, neoadjuvant chemotherapy alone may result in an acceptable tumour response and disease-free survival. Tumour response might be predicted early.