Neoadjuvant treatment for locally advanced rectal cancer: a systematic review

We reviewed the history and the current status of neoadjuvant treatment for locally advanced rectal cancer (LARC) in Western countries and Japan. The introduction of total mesorectal excision (TME) and preoperative radiotherapy (RT) were treatment revolutions that resulted in improved local control after curative resection for rectal cancer. However, local relapses still occur, even in the era of TME, and remain a cause of recurrence worldwide. The high rate of distant metastasis after curative resection remains a problem. Furthermore, the introduction of newly developed cytotoxic agents into the LARC treatment strategy continues to be an ongoing challenge. Shifting part of an adjuvant chemotherapy (CTx) regimen to the preoperative period is a promising strategy. Currently, various novel methods, such as induction CTx, consolidation CTx, concomitant administration with RT, and neoadjuvant CTx without RT, have been attempted worldwide. Although some strategies have shown favorable short-term outcomes, the long-term efficacy of the treatments needs be evaluated. At the same time, we must investigate clinical and/or molecular biomarkers to predict the therapeutic effects of each treatment, which is the fastest route to providing ideal personalized therapy for patients with LARC.