The majority of cancer incidence and mortality occurs in individuals aged older than 65 years, and the number of older adults with cancer is projected to significantly increase secondary to the aging of the US population. As such, understanding the changes accompanying age in the context of the cancer patient is of critical importance. Age-related changes can impact tolerance of anticancer therapy and can shift the overall risk-benefit ratio of such treatment. A challenge in implementing evidence-based approaches in older adults is the under-representation of this group in oncology clinical trials. In addition, although older adults are particularly vulnerable to the side effects of cancer therapy, few oncology studies to date have incorporated a measure of health status other than the Eastern Cooperative Oncology Group or Karnofsky performance scales. Novel metrics such as frailty indices or the geriatric assessment recognize heterogeneity among older adults, and may allow for risk-adapted approaches to therapy. It is increasingly recognized that several laboratory markers may predict morbidity and mortality in older adults; these biologic variables may further aid in stratifying this group of patients based on risk. This review describes key studies from the geriatric literature that provide principles for assessing health status in the older patient, and ways that these principles can be applied to oncology care in an older population are proposed.