The association of postoperative morbidity and age on 5-year survival after colorectal surgery in the elderly population: a nationwide cohort study

This study aimed to evaluate the association of age and postoperative morbidity on 5-year overall survival (OS) after elective surgery for colorectal cancer. Patients undergoing elective, curatively intended surgery for colorectal cancer Union for International Cancer Control Stages I-III between January 2014 and December 2019 were selected from four Danish nationwide healthcare databases. Patients were divided into four groups: group I 65-69 years old; group II 70-74 years old; group III 75-79 years old; and group IV ≥80 years old. Propensity score matching was used to reduce potential confounding bias. The primary outcome was the association of age and postoperative morbidity with 5-year OS. The secondary outcome was conditional survival, given that the patient had already survived the first 90 days after surgery. After propensity score matching with a 1:1 ratio, group II contained 2221 patients; group III 952 patients; and group IV 320 patients. There was no significant difference in 5-year OS between group I (reference) and groups II and III (P = 0.4 and P = 0.9, respectively). Patients with severe postoperative complications within 30 days after surgery had a significantly decreased OS (P