BACKGROUND: Multidisciplinary Geriatric-Oncology (GO-MDC) clinic performed comprehensive geriatric assessment (CGA) to determine frailty and chemotherapy toxicity risk. METHOD: Retrospective cohort study of patients ≥65 years seen between April 2017 to March 2022. We compared Eastern Cooperative Oncology Group-Performance Status (ECOG-PS) to CGA as a determinant of frailty and risk of toxicity from chemotherapy. RESULTS: Mean age of the 66 patients was 79 years. Eighty-five percent were Caucasian. Predominant cancers were breast (30%), and gynecological (26%). One-third were stage 4. The CGA identified fit (35%), vulnerable (48%), and frail (17%) patients whereas ECOG-PS classi- fied 80% as fit. CGA assessed 57% of ECOG-fit patients as vulnerable or frail (p<0.001). High chemotherapy toxicity risk using CGA was 41% and using ECOG was 17% (p=0.002). CONCLUSION: At GO-MDC, CGA was a better predictor of frailty and toxicity risk than ECOG-PS. Treatment modification was recommended in one-third of patients. [ABSTRACT FROM AUTHOR]