Functional Assessment of the Older Patient With Cancer

The population of the United States and other industrialized nations is aging rapidly. The increased life span allows for longer exposure to carcinogens and the accumulation of genetic alterations. Thus, the incidence of cancer is increasing along with the aging of the population. Patients aged ≥ 65 years account for approximately 60% of new cancer cases and 70% of all cancer mortality annually.[1]

Health and functional ability vary more in older adults than in younger patients. Even without the presence of actual disease, aging itself causes gradual, progressive loss in the biologic reserve necessary for the body to maintain physiologic homeostasis under stress, a phenomenon called “homeostenosis.” Even in healthy and highly functioning older adults, there is some degree of loss in the ability to tolerate stress. In addition, many older adults have one or more chronic medical conditions, which further decrease their organs' reserve and ability to respond to stress. Over time, increasing homeostenosis contributes to a gradual but progressive decline in the ability to function in the environment and to tolerate illness and disease.

In the general geriatric population, functional status and level of dependency have been found to predict survival.[2] For the older adult with cancer, then, the oncologist must be able to stage not only the cancer but also consider how a patient's functional status may affect the ability to tolerate and respond to treatment.[3] To accommodate this variable homeostenosis in older patients with cancer and increase their chances for survival, treatment plans need to be more individualized than for the younger population.

Many oncologists use the Karnofsky performance status score (KPS) or Eastern Cooperative Oncology Group (ECOG) scale to assess a patient's ability to perform daily tasks. However, with older patients, these scales often miss subtle degrees of functional impairment.[4] While about 80% of older adults with cancer have an ECOG performance status of 0 or 1 at the time of diagnosis, more than 50% of these patients require assistance with instrumental activities of daily living such as driving, shopping, and managing finances.[5] This functional dependence can have a negative impact on treatment tolerance and survival.[6] For the older adult with cancer, a broader assessment of function is needed.

Geriatricians use standardized assessment tools to distinguish clinical functional age from chronologic age; this is referred to as a comprehensive geriatric assessment (CGA). In the older adult with cancer, the goal of such an assessment would be to identify subtle functional issues that might contribute to morbidity and mortality independent of cancer therapy.

This article identifies some of the tools utilized by geriatricians in assessing the functional status of older adults. We also review the literature that supports the validity of these tools in the general geriatric population and, if available, in the geriatric oncology population. With these tools, oncologists could identify problems that, if modified, would potentially improve the older adult's ability to tolerate treatment.