Long-Term Outcomes in Patients With Locally Advanced Rectal Cancer Following R1 Resection After Either Induction Chemotherapy and Chemoradiotherapy or Chemoradiotherapy Alone

•R1 resection after locally advanced rectal cancer entails high recurrence rates.•Effects of induction chemotherapy have not been investigated for R1 resection only.•Induction chemotherapy plus chemoradiotherapy seem to improve local disease control.•High-risk patients should receive an intensified neoadjuvant treatment regime. Total neoadjuvant treatment (TNT) with induction chemotherapy (ICT) followed by chemoradiotherapy (CRT) has improved long-term outcomes for patients with locally advanced rectal cancer (LARC). However, long-term outcomes have not been investigated for patients with incomplete (R1) resection separately. This study investigates overall survival (OS), disease-free survival (DFS) and local and distant recurrence rates in patients with R1 resection after preoperative treatment with ICT and CRT or CRT. From the NORD database 689 patients with LARC who received treatment between 2006 and 2017 were screened for inclusion. All patients with R1 resection were included. ICT consisted of at least 1 cycle of capecitabine and oxaliplatin (CAPOX) and was followed by radiotherapy concomitant with capecitabine. Among 46 patients with R1 resection, 27 (59%) received both ICT and CRT, and 19 (41%) patients received CRT. The 5-year OS was 44% (95% CI, 26%-63%) (ICT + CRT) versus 37% (95% CI, 15%-59%) (CRT) (P = .25) and 5-year DFS was 44% (95% CI, 26%-63%) (ICT + CRT) versus 32% (95% CI, 11%-53%) (CRT) (P = .22). The local recurrence rates showed a small nonstatistical significant difference in local control in the ICT group: 15% compared to 26% in the CRT group (P = .22). Distant recurrence rates were similar: 41% (ICT + CRT) versus 47% (CRT) (P = .48). There was no significant difference in OS, DFS or local and distant recurrence rates between patients who received ICT + CRT versus patients who received CRT only. The long-term effects of induction chemotherapy plus standard chemoradiotherapy have not been investigated separately for patients with R1 resection. In this study 689 patients with locally advanced rectal cancer were screened for inclusion; 46 patients with R1 resection were included. No statistical significant difference was found in overall survival, disease-free survival, or local and distant recurrence rates.