Delayed Surgery after Neoadjuvant Short-course Radiation for Rectal Cancer Improves Pathologic Outcomes without Impacting Survival: A National Cancer Database Analysis

Interval to surgery following short course radiotherapy (SCRT) for rectal cancer is not standardized. This study investigated pathologic outcomes and survival with varying intervals to surgery.

Using the National Cancer Database, adults who received SCRT from 2005 to 2020 were grouped by additional neoadjuvant chemotherapy. Outcomes were analyzed for early (within 1 week) and delayed (over 4 weeks) intervals.

Of 1154 patients, 671 received neoadjuvant SCRT and chemotherapy (Group 1: median interval 29 days, 50% delayed) and 483 received SCRT only (Group 2: median interval 9 days, 27% delayed). In Group 1, delay was associated with tumor downstaging (OR 1.61; 95% CI, 1.03–2.51; p = 0.036), decreased lymphovascular invasion (OR 0.53; 95% CI, 0.33–0.85; p = 0.009), and complete pathologic response (OR 2.86; 95% CI, 1.06–7.76; p = 0.039). Delay was associated with decreased tumor deposits in Group 1 (OR 0.46; 95% CI, 0.30–0.71; p < 0.001) and Group 2 (OR 0.37; 95% CI 0.21–0.65; p = 0.001). Survival was not affected.

Delaying surgery following neoadjuvant SCRT results in favorable pathologic outcomes without impacting overall survival, regardless of neoadjuvant chemotherapy.