Physiologic Aspects of Aging

Abstract

A gradual diminution in the physiologic reserve or functional capacity over time is the characteristic hallmark of aging, and this has a direct impact on the choice of cancer therapy and its toxicity profile in elderly patients with cancer. With the expected rapid rise of the older population as a subgroup, oncologists will increasingly treat elderly patients. Provision of competent care to this increasing pool of older patients with cancer necessitates that oncology professionals become familiar with age-associated changes in organ physiology and their impact on cancer treatment and toxicity. In this comprehensive review, we have listed changes in cardiovascular, gastrointestinal, pulmonary, and renal physiology with aging. Also enumerated is the impact of these changes on cancer therapy and toxicity in each organ system-based section. Cardiovascular changes primarily lead to reduction of the cardiac functional reserve, with a consequent increase in the risk of congestive heart failure. Changes in gastrointestinal physiology lead to increased mucosal damage. A reduction in pulmonary reserve has implications for postradiation complications, and a decline in renal function leads to an increased potential for nephrotoxicity. These changes impair the ability of older patients with cancer to tolerate cancer therapy and increase their risk of toxicities. This may lead to an overall decline in functional status, resulting frailty, poor quality of life, and ultimately poor outcomes. Becoming familiar with age-related physiologic changes is the first step for oncologists seeking to better tailor their treatments. This, combined with adoption of some of the clinical interventions suggested in this review, can help better manage the geriatric oncology patient. Further research is necessary for the development of more specific evidence-based recommendations.

Rationale and design of the Caloric Restriction and Exercise protection from Anthracycline Toxic Effects (CREATE) study: a 3-arm parallel group phase II randomized controlled trial in early breast cancer

“…A gradual decline in physiologic reserve of all tissues and organ systems is a hallmark of aging and many chronic diseases [43, 44]. Chemotherapy has the potential to rapidly accelerate this decline.…”

Bladder cancer in the elderly

“…17,19,20 The degree and timeline of this decline vary among different individuals and organ systems. Although these changes are generally imperceptible over the years, they can be unmasked through various internal and external stressors.…”

“…17,19,20,25,26 Moreover, there is a decreased response to catecholamines with stress. 25,26 Depending upon obesity, heredity factors, nutrition, weight loss, diet, and racial differences, such changes may be increasingly accentuated over time.…”

“…17,19,20,27 These are further affected by earlier environmental exposure to substances that may lead to emphysema, asthma, and decreased pulmonary reserve. 19,20 …”

Determining Chemotherapy Tolerance in Older Patients With Cancer

“…Studies have shown that overall health is more predictive for chemotherapy tolerance than chronologic age. 6-10 Although decreased organ function is experienced universally with aging, 11,12 the rate and degree of decline differs from person to person as a result of unique genetic and environmental factors. The standard oncology workup provides vital information to guide management of all patients with cancer, but it is not sufficient to identify those who are more vulnerable to treatment complications.…”