Neoadjuvant chemotherapy in locally advanced colon cancer: A systematic review with proportional meta-analysis

Neoadjuvant chemotherapy is suggested in locally advanced colon cancer. Data on improved long-term oncological outcomes are lacking, which hampers the implementation in clinical practice. This systematic review provides an overview of the benefits and drawbacks of neoadjuvant chemotherapy in patients with locally advanced colon cancer. A systematic literature search was performed using Embase (OVID), MEDLINE (OvidSP), and the Cochrane Library. Studies reporting on the efficacy of neoadjuvant chemotherapy in patients with operable, locally advanced colon cancer without metastases at the time of diagnosis were considered eligible for inclusion. An overview of short- and long-term outcomes of neoadjuvant chemotherapy is provided based on available literature. Additionally, proportional meta-analyses were performed using MedCalc Statistical Software version 19.2.6. A total of 17 unique studies were included in this review, 3 randomised controlled trials and 14 prospective single-arm or retrospective studies. The maximum reported dropout before surgery was 7.8 % in the neoadjuvant chemotherapy group. A histopathological complete response after neoadjuvant chemotherapy was observed in 0-4.8 % of the patients. The occurrence of anastomotic leaks was less than 8 % for both patients treated with neoadjuvant chemotherapy and patients treated with upfront surgery. Neoadjuvant chemotherapy is a safe alternative for adjuvant chemotherapy based on the dropout rate before surgery and the peri-operative morbidity and peri-operative mortality. Robust long-term survival outcomes are lacking and serious concerns regarding the risk of overtreatment have been expressed. Hence, neoadjuvant chemotherapy might be considered in a select group of patients with locally advanced colon cancer.