Neoadjuvant treatments for resectable rectal cancer: A network meta-analysis

Different neoadjuvant therapy regimens are available for rectal cancer, but the relative effects are controversial. The aim of the present network meta-analysis (NMA) was to estimate the relative efficacy and safety of neoadjuvant therapies for resectable rectal cancer. MEDLINE, EMBASE and Cochrane Central Registry of Controlled Trials were searched for publications dated from 1946 up to June 2018. The present study included randomized clinical trials that compared treatments for resected rectal cancer: Surgery alone, surgery preceded by neoadjuvant radiotherapy (RT), neoadjuvant chemotherapy (CT) or neoadjuvant chemoradiotherapy (CRT). Direct pairwise comparisons and NMA were conducted. A total of 23 randomized controlled trials were included in the present study. RT had an overall survival (OS) benefit when compared with surgery alone [HR (hazard ratio), 0.89; 95% confidence interval (CI), 0.82-0.97; quality of evidence, high]. All three neoadjuvant regimens were associated with lower local recurrence (LR) when compared with surgery alone [RT: odds ratio (OR), 0.44; 95% CI, 0.35-0.65; quality of evidence, high; CRT: OR, 0.34; 95% CI, 0.23-0.56; quality of evidence, low and CT: OR, 0.32; 95% CI, 0.11-1.00; quality of evidence, low]. There were no significant differences in OS and LR between CRT and RT (OS: OR, 1.10); 95% CI, 0.93-1.20; LR: OR, 0.81; 95% CI, 0.61-1.10). Ranking probabilities indicated that CRT was the best strategy for local control, with a surface under the cumulative ranking curve (SUCRA) of 78.78%. Patients treated with RT had improved disease-free survival compared with those treated with surgery alone (HR, 0.82; 95% CI, 0.64-1.00; quality of evidence, low). Neoadjuvant RT or CRT did not significantly improve distant metastases compared with surgery alone (RT: OR, 0.87; 95% CI, 0.69-1.10 and CRT: OR, 0.75; 95% CI, 0.47-1.10). CRT had an improved pathological complete response rate compared with RT (OR, 4.90; 95% CI, 21.80-17.00; quality of evidence, low). No significant difference for the risk of anastomotic leak between each treatment was observed in the NMA. In conclusion, RT decreased the LR and improved OS compared with surgery alone for resected rectal cancer. CRT was the best neoadjuvant therapy analyzed and CT was likely the second best for all outcomes based on SUCRA. However, these findings were limited by overall low quality of evidence.