O133 Network meta-analysis of neoadjuvant therapy in rectal cancer

Abstract Introduction Locally advanced rectal cancer can be treated with neoadjuvant chemoradiotherapy prior to surgical resection. This treatment can significantly downstage rectal tumours and consequently lead to improved long term survival and reduced risk of local reoccurrence. Controversy exists regarding the optimal regime for neoadjuvant therapy. A network meta-analysis allows the integration of multiple treatments to be compared simultaneously in a single analysis. This network meta-analysis aims to assess which neoadjuvant regime gives the highest rate of pathological complete response (pCR). Methods An extensive literature search for randomised controlled trials of neoadjuvant therapy in rectal cancer was performed. The primary outcome was pCR at surgical resection. Direct and indirect comparisons were performed with a frequentist Network Meta-Analysis and results tested for consistency. Results Following critical appraisal of 3720 studies, 16 randomised control trials were included in the study. Regimes of neoadjuvant therapy included short course radiotherapy with concurrent chemotherapy or without, long course chemoradiotherapy, long course chemoradiotherapy with either induction of consolidation chemotherapy, and radiotherapy alone (45gy). Short course radiotherapy combined with chemotherapy was shown to produce significantly higher pCR in patients with rectal cancer. Short course radiotherapy without chemotherapy was shown to have the lowest rate of pCR. Conclusion There is strong evidence to suggest that short course chemoradiotherapy is the best regime to produce the highest pCR in patients with rectal cancer.