Outcomes Following Recent and Distant Neoadjuvant Radiation in Rectal Cancer: An Institutional Retrospective Review and Analysis of NSQIP.

BACKGROUND:Neoadjuvant chemoradiotherapy (nCRT) is the standard of care in locally advanced rectal cancer (LARC). However, radiation therapy is thought to increase operative difficulty due to induction of fibrosis. Total neoadjuvant therapy (TNT) protocols increase the time between completion of radiation and surgical resection which may lead to increased operative difficulty and complications. METHODS:A single institution retrospective review of patients ≥18 years with LARC undergoing nCRT from 2015 to 2022. Patients were dichotomized in 2 cohorts: <90 days from radiation to surgery (recent radiation), and ≥90 days from radiation to surgery (distant radiation). Institutional data was compared to National Surgical Quality Improvement Program (NSQIP) rectal cancer data from 2016 to 2020. Outcomes included intraoperative complications, 30-day morbidity, and oncologic outcomes. RESULTS:One hundred forty-six institutional patients included, 120 had recent radiation, 26 had distant radiation. Thirty-day morbidity and intraoperative complications did not differ. There was greater radial margin positivity (7% vs. 24%), fewer lymph nodes harvested (17 ± 5 vs. 15 ± 6), and a lower rate of complete mesorectal dissection (88% vs. 65%,) in distant radiation patients 3059 patients were included in NSQIP analysis, 2029 completed radiation <90 days before surgery and 1030 without radiation 90 days before surgery. Patients without radiation 90 days preoperatively had more radial margin positivity (9.2% vs. 4.6%), organ space infection (8.6% vs. 6.4%), and pneumonia (2.2% vs. 0.9%). CONCLUSION:The present study suggests that increased time between radiation and surgery results in more challenging dissection with less complete mesorectal dissection and increased radial margin positivity without increasing technical complications.