Background: We aimed to evaluate the potential utility of the Robinson Frailty Score (RFS), the Edmonton Frail Scale (EFS), and the G8 tool for predicting postoperative adverse events (AEs) in older adults with cancer.Methods: We included consecutive older adults evaluated at geriatric oncology service before undergoing oncologic surgery between September 2018 and December 2019. The RFS measures cognition, function, falls, comorbidity, albumin, and hematocrit. The EFS evaluates cognition, function, incontinence, self-perceived health, mood, nutrition, polypharmacy, and social support. These scales classify patients into three frailty categories (fit, pre-frail, or frail). The G8 score was dichotomized at a cut-off value of 14. The primary outcome was composite AEs including 30-day postoperative complications (>Clavien-Dindo grade II) and discharge to an institutional care facility. The severity of surgery was assessed using the Operative Stress Score (OSS).Results: Among 114 patients (median age 80 years, range 72-96 years), the main surgery types were gastrointestinal (62%), and head and neck (20%). Using the OSS, surgical procedures were classified as very low to low-stress (9%), moderate-stress (31%), high-stress (46%), and very high-stress (15%). Fortyfive patients (40%) experienced postoperative AEs. After adjusting for the OSS, preoperative RFS was significantly associated with AEs (fit: 25%, pre-frail: 49%, frail: 77%; p < 0.01). However, the EFS (fit: 30%, pre-frail: 37%, frail: 60%; p = 0.14) and the G8 tool (score >14: 17%, score <14: 41%; p = 0.07) were not significantly associated with the risk of AEs.Conclusion: The RFS is predictive of postoperative AEs in older adults undergoing elective surgery for cancer.(c) 2020 Elsevier Ltd, BASO -The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.