Aging and Cancer
Aging and Cancer
Management of cancer in the older person is an increasingly common challenge. If the older population continues to grow at the present rate, 60% of all neoplasms will occur in the 20% of the population aged 65 and older in approximately 12 years. Dr. Kennedy has been at the forefront of the battle against cancer for more than 40 years. From this privileged position, he has been among the first to recognize emerging issues, including the issue of cancer and aging.
This article illustrates the evolving panorama of oncology through the vision of a leader. My role is to define the steps of the trajectory outlined by Dr. Kennedy to achieve optimal cancer control in the older person (Table 1).
The Evolving Definition of ‘Aging’
The clinical definition of aging is essential for any practice involving older individuals, not just oncology. The definition is evolving with our understanding of aging and with the successful prevention of disease and disability. However, consensus exists on these general issues:
Aging may be interpreted as a progressive loss of the functional reserve of multiple organ systems. This decline, which occurs at different rates for different people and in different systems in the same person, is poorly reflected by chronologic age.
At present, functional age is assessed on the basis of personal health (comorbidity), ability to perform activities/instrumental activities of daily living, and the presence of so-called geriatric syndromes. Several stages of aging, with different life expectancies and levels of stress tolerance, have been proposed. For practical purposes, patients staged as "frail" are generally not good candidates for aggressive forms of treatment.
Social, nutritional, and pharmacologic assessments provide useful information. The availability of a competent caregiver is essential in any form of outpatient treatment.
As a result of this consensus, experts at the National Comprehensive Cancer Network’s 2000 conference proposed that some form of geriatric assessment be performed in the evaluation of all cancer patients aged 70 and older.
Components of Cancer Care in the Elderly
Aging and cancer are linked by at least three mechanisms: length of carcinogenesis, increased susceptibility of aging tissues to environmental carcinogens, and diminished host defenses, such as immune senescence. These mechanisms may be offset by chemoprevention, which represents a real opportunity for cancer control in older individuals.
The behavior of some cancers, including breast, lung, and ovarian cancer, non-Hodgkin’s lymphoma, and acute myelogenous leukemia, may change with the age of the patients. These changes may be due to alterations in the neoplastic cell itself (as in the case of acute myelogenous leukemia) or to alterations in the tumor host (as appears to be the case in non-Hodgkin’s lymphoma). A better definition of tumor-host interaction may help the practitioner define the prognosis of individual neoplasms.
Perhaps the most critical barrier to the prevention and treatment of cancer in older individuals is lack of support by their primary care provider, a point Dr. Kennedy properly highlighted. Hopefully, this barrier will be overcome by a better understanding of aging and by the aging of a generation of people more used to taking responsibility for their own medical care.
Other barriers include limited access to care due to transportation, economic restriction, and inadequate social support. A geriatric assessment is the clue to identifying and overcoming these barriers.
As Dr. Kennedy points out, participation of older individuals in clinical trials is essential, to accrue reliable information related to the benefits of prevention and treatment. Cancer research in the older person needs to address the following issues:
how to facilitate patient accrual,
how to revisit the end point of the trial, and
how to account for the diversity of the geriatric population.
The adoption of a uniform geriatric assessment may provide a common language with which to classify patientsnot unlike the performance status did for younger individuals. Patient accrual may be facilitated by the promotion of community-based clinical trials, simplification of the informed-consent process, and avoidance of uncomfortable and expensive diagnostic tests. In my experience, comprehension of randomization has been particularly difficult for older individuals, especially when only one treatment arm involves cytotoxic chemotherapy and the other involves observation or hormonal treatment.
The definition of treatment end points should be congruent with the patient’s life expectancy and function. For example, it is unlikely that adjuvant chemotherapy results in improved survival for breast cancer patients aged 80 and older. Yet, prevention of cancer recurrence may improve the quality of life of these patients. Decisional models that take life expectancy and quality of life into account may help define the proper end points for different clinical trials.
As claimed by Dr. Kennedy, ageism may well have excluded patients from life-saving cancer treatment. At present, however, some encouraging trends are emerging. A recent study at Harvard University found that older individuals with breast cancer generally receive treatment that is appropriate to their condition.
Improving Cancer Control in Older Patients
The geriatric assessment should be the cornerstone of individualized cancer treatment. At the same time, simple provisionsincluding the prophylactic use of growth factors in patients aged 70 and older, treated with moderately toxic chemotherapy (such as CHOP [cyclophosphamide (Cytoxan, Neosar), doxorubicin HCl, vincristine (Oncovin), and prednisone]), and maintenance of hemoglobin levels ³ 12 g/dLmay render cancer treatment safer and probably less expensive in the majority of older patients.
Cancer control in the older person is an interdisciplinary endeavor involving basic, clinical, and social scientists. It also involves the strict cooperation of primary care and specialty providers, as well as the patient’s social network. Dr. Kennedy has laid a solid foundation for this effort.
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