Consolidation chemotherapy with capecitabine after neoadjuvant chemoradiotherapy in high-risk patients with locally advanced rectal cancer:Propensity score study

BACKGROUND The effects of consolidation chemotherapy(CC) in neoadjuvant therapy in locally advanced rectal cancer(LARC) have been explored. However, the optimal neoadjuvant chemoradiotherapy(NCRT) and surgery interval, regimen, and cycles of chemotherapy remains unclear.AIM To evaluate the effects of one to two cycles of CC with capecitabine on high-risk patients with LARC without extending NCRT and surgery interval.METHODS We retrospectively evaluated high-risk patients with LARC, who were defined as having at least one of the following factors by magnetic resonance imaging: depth of invasion beyond the muscularis propria of more than 5 mm(c T3c-c T3d), T4, meso-rectal fascia or extramural vascular invasion positive, and treatment date between January 2015 and July 2019 in our center. Patients were divided into the CC and non-CC group according to whether they received CC(capecitabine 1000 mg/m~2 twice daily from days 1 to 14 every 21 d) after NCRT. Propensity score matching(PSM) and inverse probability of treatment weight(IPTW) were used to balance the differences between the two groups. The main outcome was the complete response(CR) rate.RESULTS A total of 265 patients were enrolled: 136 patients in the CC group and 129 patients in the non-CC group. The median interval was 70 d(range, 37-168). The CR rate was 24.3% and 16.3%(P = 0.107) in the CC and non-CC groups’ original samples, respectively. After PSM and IPTW, the CR rate in the CC group was higher than that in non-CC group(27.6% vs 16.2%, P = 0.045; 25.9% vs 16.3%, P = 0.045). The median follow-up was 39.8 mo(range, 2.9-74.8), and there were no differences in 3-year non-regrowth disease-free survival nor overall survival in the original samples(73.2% vs 71.9%, P = 0.913; 92.3% vs 86.7%, P = 0.294), PSM(73.2% vs 73.5%, P = 0.865; 92.5% vs 89.3%, P = 0.612), and IPTW(73.8% vs 72.1%, P = 0.913; 92.4% vs 87.4%, P = 0.294). There was also no difference in grade 2 or higher acute toxicity during neoadjuvant therapy in the two groups(49.3% vs 53.5%, P = 0.492).CONCLUSION One to two cycles of CC with capecitabine after NCRT was safe and increased the CR rate in highrisk LARC but failed to improve the long-term outcomes.