Background: Data relating to cancer treatment in the older patient population are limited because older individuals have been under-represented in clinical trials. The goal of this review was to establish which factors hinder the participation of older individuals to clinical trials and to examine possible solutions.
Methods: The literature relating to cancer treatment in the older patient population was reviewed.
Results: The benefit of systemic cancer treatment may decrease with age, and risks may be increased due to reduced life expectancy and reduced tolerance of stress in the older population. Therefore, a multipronged approach is recommended for clinical studies in these patients, including phase 2 studies limited to persons 70 years of age and older, stratification by life expectancy and predicted treatment tolerance in phase 3 studies, and registration studies to establish predictive variables for treatment-related toxicity in older individuals.
Conclusions: A combination of prospective and registration studies may supply adequate information to study cancer treatments in the older patient population.
The study of cancer care in the older population is a complex task. The word “complex” derives from the Latin cum plexere, meaning to weave together. In an older person, many interwoven conditions may conspire to reduce life expectancy, the tolerance of stress, and the ability to live independently.1 Anemia in an older person is an example of such a complexity, because it may be affected by multiple causes, including hemopoietic insufficiency, chronic renal dysfunction, chronic inflammation, and iron deficiency from chronic bleeding and iron malabsorption.2
The study of cancer care in the older population must take into account the complexity of aging; therefore, as described in this article, a multipronged approach is needed for this patient population.
Definition of Age
Aging is associated with common trends that include a decreased functional reserve of multiple organ systems and an increased susceptibility to diseases and injuries.1 These changes occur at different rates in different individuals and are poorly reflected in chronological age. The assessment of physiological, rather than chronological, age is paramount to the enrollment of older individuals in clinical trials of cancer treatment. Chronological age may be used as a landmark to establish when the assessment of physiological age becomes necessary, and this landmark is commonly established to be 70 years of age3; however, this statement does not imply that all individuals 70 years of age and older are elderly.
Assessment of Physiological Age
Age is associated with decreased life expectancy and tolerance of stress. Thus, the determination of physiological age may be based on the assessment of mortality risk and stress-related complications. For this purpose, the best validated instrument is a Comprehensive Geriatric Assessment (CGA; Table 1).3-5
Activities of daily living (ADLs) are activities necessary to basic survival and include transferring, eating, grooming, dressing, going to the bathroom alone, and continence. A person dependent in at least 1 ADL requires a full-time caregiver or admission to an assisted-living facility. In general, patients dependent in at least 1 ADL have a limited life expectancy, a limited tolerance for stress, and are candidates for palliative care; however, exceptions do exist. If a patient who was previously independent is now ADL dependent due to a treatable neoplastic condition, such as lymphoma, then treatment is indicated. In these situations, treatment may reverse ADL dependence. Instrumental activities of daily living (IADLs) are activities necessary to live independently and include the use of transportation, ability to take medications, to use the telephone, to manage one’s finances, and to provide to one’s meals. A person dependent in one or more IADLs will require assistance. The determination of IADLs is relevant to this review, because it implies an increased incidence of therapeutic complications in addition to an increased mortality risk.6,7 Presently, polymorbidity is a more popular term than comorbidity, implying that different diseases may influence both the treatment and the behavior of other diseases.8 Polymorbidity is associated with a decreased life expectancy, decreased tolerance to antineoplastic treatment and, in general, a poor cancer prognosis.3 Geriatric syndromes include common conditions, although not all are unique to aging.9 Patients with cancer, ADL dependence, and at least 1 geriatric syndrome are candidates for symptom control, unless the geriatric syndrome is reversible. Malnutrition is a common complication of both cancer and aging and is associated with a decreased tolerance of chemotherapy and decreased immune function.10