Application of oxaliplatin combined with capecitabine in preoperative concurrent chemoradiotherapy for locally advanced rectal cancer

Objective To assess the efficacy and safety of oxaliplatin combined with capecitabine in preoperative concurrent chemoradiotherapy for high-risk locally advanced rectal cancer. Methods 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. Results 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. Conclusion 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. Key words: Rectal neoplasms; Antineoplastic combined chemotherapy protocols; Oxaliplatin; Capecitabine