Identification of the risks of postoperative complications may be challenging in older patients with heterogeneous physical and cognitive status. The aim of this multicentre, observational study was to identify variables that affect the outcomes of colon cancer surgery and, especially, to find tools to quantify the risks related to surgery. Method: Patients aged ≥80 years with electively operated Stage I-III colon cancer were recruited. The prospectively collected data included comorbidities, results of the oncogeriatric screening tool (G8), Clinical Frailty Scale (CFS), Charlson Comorbidity Index (CCI) and Mini Nutritional Assessment-Short Form (MNA-SF), and operative and postoperative outcomes. Results: A total of 161 patients (mean 84.5 years, range 80-97, 60% female) were included. History of cerebral stroke (64% vs. 37%, p = 0.02), albumin level 31-34 g/l compared with ≥35 g/l (57% vs. 32%, p = 0.007), CFS 3-4 and 5-9 compared with CFS 1-2 | 1825 NIEMELÄINEN Et aL.