Contemporary,national patterns of surgery after preoperative therapy for stageⅡ/Ⅲrectal adenocarcinoma

BACKGROUND Contemporary treatment of stageⅡ/Ⅲrectal cancer combines chemotherapy,chemoradiation,and surgery,though the sequence of surgery with neoadjuvant treatments and benefits of minimally-invasive surgery(MIS)is debated.AIM To describe patterns of surgical approach for stageⅡ/Ⅲrectal cancer in relation to neoadjuvant therapies.METHODS A retrospective cohort was created using the National Cancer Database.Primary outcome was rate of sphincter-sparing surgery after neoadjuvant therapy.Secondary outcomes were surgical approach(open,laparoscopic,or robotic),surgical quality(R0 resection and 12+lymph nodes),and overall survival.RESULTS A total of 38927 patients with clinical stageⅡorⅢrectal adenocarcinoma underwent surgical resection from 2010-2016.Clinical stageⅡpatients had neoadjuvant chemoradiation less frequently compared to stageⅢ(75.8%vs 84.7%,P<0.001),but had similar rates of total neoadjuvant therapy(TNT)(27.0%vs 27.2%,P=0.697).Overall rates of total mesorectal excision without sphincter preservation were similar between clinical stageⅡandⅢ(30.0%vs 30.3%)and similar if preoperative treatment was chemoradiation(31.3%)or TNT(30.2%).Over the study period,proportion of cases approached laparoscopically increased from 24.9%to 32.5%and robotically 5.6%to 30.7%(P<0.001).This cohort showed improved survival for MIS approaches compared to open surgery(laparoscopy HR 0.85,95%CI 0.78-0.93,and robotic HR 0.82,95%CI 0.73-0.92).CONCLUSION Sphincter preservation rates are similar across stageⅡandⅢrectal cancer,regardless of delivery of preoperative chemotherapy,chemoradiation,or both.At a national level,there is a shift to predominantly MIS approaches for rectal cancer,regardless of whether sphincter sparing procedure is performed.