Most malignancies are diagnosed in older adults who are potentially susceptible to aging-related health conditions; however, the manifestation of geriatric syndromes during surgical cancer treatment is not well quantified. Accordingly, we sought to assess the prevalence and ramifications of geriatric events during major surgery for cancer.Using Nationwide Inpatient Sample data from 2009 to 2011, we examined hospital admissions for major cancer surgery among elderly patients (ie, age ≥ 65 years) and a referent group age 55 to 64 years. From these observations, we identified geriatric events that included delirium, dehydration, falls and fractures, failure to thrive, and pressure ulcers. We then estimated the collective prevalence of these events according to age, comorbidity, and cancer site and further explored their relationship with other hospital-based outcomes.Within a weighted sample of 939,150 patients, we identified at least one event in 9.2% of patients. Geriatric events were most common among patients age ≥ 75 years, with a Charlson comorbidity score ≥ 2, and who were undergoing surgery for cancer of the bladder, ovary, colon and/or rectum, pancreas, or stomach (P < .001). Adjusting for patient and hospital characteristics, those patients who experienced a geriatric event had a greater likelihood of concurrent complications (odds ratio [OR], 3.73; 95% CI, 3.55 to 3.92), prolonged hospitalization (OR, 5.47; 95% CI, 5.16 to 5.80), incurring high cost (OR, 4.97; 95% CI, 4.58 to 5.39), inpatient mortality (OR, 3.22; 95% CI, 2.94 to 3.53), and a discharge disposition other than home (OR, 3.64; 95% CI, 3.46 to 3.84).Many older patients who receive cancer-directed surgery experience a geriatric event, particularly those who undergo major abdominal surgery. These events are linked to operative morbidity, prolonged hospitalization, and more expensive health care. As our population ages, efforts focused on addressing conditions and complications that are more common in older adults will be essential to delivering high-quality cancer care.