[Research hotspot and progress of preoperative chemoradiotherapy for rectal cancer]

Preoperative chemoradiotherapy (CRT) has become an important component of comprehensive treatment for rectal cancer. Although local recurrent risk has been remarkably reduced by CRT, distant metastasis remains the main cause of therapeutic failure. Therefore, more and more studies focused on controlling distant metastasis in order to prolong long-term survival. Recently, CRT has achieved certain progression in rectal cancer: (1)Patients with stage T3 should be classified into specific subgroups to formulate individualized treatment regimen. For stage T3a, it is feasible to perform surgery alone or administrate low intensity preoperative CRT; for stage T3b and T3c, conventional preoperative CRT should be performed in order to reduce the risk of recurrence postoperatively. (2)With regard to combined regimen for chemotherapy, oral capecitabine superiors to intravenous bolus 5-fluorouracil (5-FU) and is comparable to continuous intravenous infusion 5-FU with a better safety. Therefore, capecitabine is recommended for older patients and those with poor tolerance to chemotherapy. Compared to single 5-FU concurrent CRT, addition of oxaliplatin into preoperative CRT may result in a higher survival benefit in Chinese patients. As to the application of irinotecan, bevacizumab or cetuximab, unless there are more evidence to confirm their efficacy and safety from randomized controlled trial, they should not be recommended for adding to preoperative CRT routinely. (3)On the optimization in CRT pattern, the application values of induction chemotherapy before concurrent CRT, consolidation chemotherapy after concurrent CRT, neoadjuvant sandwich CRT, neoadjuvant chemotherapy alone and short-course preoperative radiotherapy remain further exploration. (4)On the treatment strategy for clinical complete response (cCR) after CRT, whether "wait and see" strategy is able to be adopted, it is still a hot topic with controversy.