To assess the efficacy and safety of oxaliplatin combined with capecitabine in preoperative concurrent chemoradiotherapy for high-risk locally advanced rectal cancer.

We retrospectively screened patients with locally advanced adenocarcinoma of the rectum (T3 or T4 with any N, or any T with node positivity) in Peking University Cancer Hospital and Institute from March 2018 to February 2019. The eligible patients had at least one of the following high-risk factors: very low cancer, clinical T4b, mesorectal fascia involvement, positive extramural venous invasion, and lateral lymph node involvement. The patients received preoperative intensity-modulated radiotherapy (95% planning gross tumor volume 50.6 Gy/95% planning target volume 41.8 Gy/22 f/30 d, a single fraction per day) with concurrent oxaliplatin 85 mg/m² at d1 per two weeks and capecitabine 825 mg/m² twice daily for 5 days per week. The primary outcome was complete response (clinical and pathologic complete response) rate. Secondary outcomes included adverse reactions, postoperative complications, R0 resection rate, anus-preserving operation rate, down-staging rate, tumor regression grade (TRG), local recurrence rate, and distant metastasis rate.

In total, 63 patients were included in the analysis. Among them, 63 (100%) completed all radiotherapy doses, and 50 (79.37%) received all three cycles of chemotherapy. There were no cases of grade 4 adverse reactions, and grade 3 adverse reactions occurred in 5 (7.94%) cases. Of 46 patients who underwent surgery, the R0 resection rate was 100%, and the anus-preserving operation rate was 73.91% (36/46). The complete response rate was 34.92% (22/63). The T and N down-staging rates were 82.61% (38/46) and 95.65% (44/46), respectively. The percentages of cases with TRG 0, 1, and 2 were 30.43% (14/46), 45.65% (21/46), and 23.91% (11/46), respectively. Postoperative complications occurred in 6 cases, all of which were relieved by conservative treatments. The median follow-up time was 7.2 months. There was no death or local recurrence during follow-up, and 4 (6.35%, 4/63) cases had distant metastasis.

For patients with high-risk locally advanced rectal cancer, oxaliplatin combined with capecitabine in concurrent chemoradiotherapy has good short-term efficacy and acceptable adverse reactions, which may be a better candidate for neoadjuvant therapy.

Rectal neoplasms; Antineoplastic combined chemotherapy protocols; Oxaliplatin; Capecitabine