Cancer, Diagnosis and Management
CANCER, DIAGNOSIS AND MANAGEMENT
While the group of Americans sixty-five years or older comprise about 13 percent of the population, 60 percent of all newly diagnosed cancers and 70 percent of all deaths from cancer occur in this age group, emphasizing the magnitude of this disease in older adults. All the major cancers primarily affect older adults, with the risk of developing cancer increasing as age increases. Of the most common cancers, 77 percent of prostate cancers, 74 percent of colon cancers, and 66 percent of lung cancers occur in elderly persons. Breast cancer, often thought to be a premenopausal disease, occurs 48 percent of the time in older women.
After heart disease, cancer is the second leading cause of death among older adults, with mortality rates increasing with advancing age. Thus not only does cancer occur at an increased rate in older adults, the possibility of dying from this disease increases as well. This phenomenon is not due to chronological age alone but is also related to the biologic characteristics of the tumor and the overall health and well-being of the older adult.
Cancer is a disease in which normal cells become abnormal with uncontrolled growth and the tendency to invade healthy tissue. Cells undergo this change, called malignant transformation, through the steps of initiation, promotion, and progression.
Initiation is the process in which the DNA of a cell is altered. External factors such as chemical carcinogens (e.g., tobacco smoke), physical carcinogens (e.g., radiation), or certain viruses and internal factors such as inherited mutations can trigger initiation. After initiation, the altered cell may exist for a long period of time without causing any problems. It is, however, susceptible to future alterations.
Promotion is the alteration of normal growth regulation. This may occur through the activation of cellular genes or oncogenes that stimulate growth, or by the deactivation of genes that normally keep growth in check, tumor suppressor genes.
Finally, during the progression step the tumor continues to grow and acquire additional DNA mutations. These abnormal cells develop the ability to invade healthy tissues, or metastasize. Metastatic potential requires additional cellular characteristics such as the ability to disrupt surrounding tissue and promote growth of new blood vessels.
In an attempt to explain the epidemiological relationship between cancer and aging, several hypotheses have been suggested. These include the possibility that aging may simply allow for the passage of sufficient time to accumulate cellular alterations. Some experiments suggest that aging cells may be more susceptible to carcinogens. Once damage occurs, it is compounded by a decreased ability to repair damaged DNA sequences.
Another area of research interest has been the role of telomeres, which are short stretches of DNA present at the ends of chromosomes. Telomeres act like anchors, protecting the stability of the rest of the DNA. As cells age, telomeres shorten, leading to genetic instability and possible mutation. Malignant cells activate a normally inactive enzyme, telomerase, a telomererepairing enzyme, to preserve their telomere length.
The goal of diagnosis for cancer is to find and treat the disease in its early stages, yielding the best survival rates. However, in elderly persons, delays in diagnosis may occur. The person must recognize the abnormal symptoms and have knowledge of the warning signs of cancer. Some older adults may explain away their new symptoms as another change due to the aging process. Physicians may delay diagnostic tests by failing to recognize new signs and symptoms in a patient with multiple disease processes.
Some clinicians believe that cancers behave less aggressively in elderly persons but research findings have been inconclusive. Once a warning symptom is noticed, older adults do not delay any more than younger people in seeking medical help. However, such symptoms and signs may be less obvious in older people due to the presence of other chronic diseases and physiologic changes. Thus, the diagnosis of cancer in older people requires vigilant attention and high suspicion of symptoms by the older adult and the physician.
In general, treatment options for cancer consist of surgery, radiation, chemotherapy, or hormonal therapies. Although these treatment choices are similar to those provided to younger patients, the treatment decision process is more involved.
A person's level of function and well-being involves the interaction between physical, emotional, social, and cognitive states. Because of these relationships, any intervention in one area will influence the level of function in the other areas and vise versa, with the level of function in the other areas influencing the success of the intervention. These interactions become more evident and important in the older adult because aging leads to progressive reduction in the reserve capacity of these four areas. Thus, in the elderly person with cancer, successful treatment will be influenced not only by that person's biologic and physical status but also by the presence of other illnesses, depression, and level of social support.
Since aging is an individualized process and chronological age only partially reflects the decrease in functional reserve, a comprehensive geriatric assessment is recommended to evaluate the true functional capacity of the elderly person with cancer. A comprehensive geriatric assessment can provide information on treatment tolerance and the likelihood of therapeutic complications, unmask coexisting conditions, and reveal social impediments to cancer treatment. An important additional component to decisionmaking is the value of the older adult's own assessment of both the quantity and the quality of potential survival during and after the treatment for the cancer. In this way, judgments weighing the risks versus the benefits of diagnostic and therapeutic interventions can be made.
Surgery may be accomplished in elderly persons with mortality and morbidity rates that are similar to younger patients. Surgical success is influenced more by the presence of other illnesses and declines in physiologic functions than by chronological age. Older adults may actually prefer the acute and time-limited stress of surgery to the more chronic or protracted courses of chemotherapy or radiation therapy.
Unlike surgery, radiation therapy has no appreciable acute mortality and is generally not limited by associated medical conditions. Side effects are determined by dose and volume of tissue irradiated, and in elderly persons the radiation effect on normal tissues is enhanced approximately 10 to 15 percent.
Due to the decline in kidney function with age, aging affects the drug properties and elimination of chemotherapeutic agents. The degree of side effects and the potential response depend predominantly on the aggressiveness of the chemotherapy regimen. Thus, chemotherapy agents must be used in dosages that have acceptable response rates with acceptable levels of side effects. Hormonal therapy for breast and prostate cancer works at least as well in elderly patients as it does in younger persons.
Supportive care should always be a part of any therapy plan. Pain relief, nutritional support, the supportive role of nursing, and communication between physicians, patient, and family regarding decisions about care directives, terminal care, and utilization of hospice services help maximize the ability to tolerate the treatment as well as the disease.
Cancer occurs in the elderly with great frequency and further research is needed to reveal the interaction of the aging process with malignant transformation. The overall approach to the formulation of a diagnostic and treatment plan for the older adult involves systematic evaluation of their functional capacity and wellbeing.
Pearl H. Seo, M.D., M.P.H. Harvey Jay Cohen, M.D.
See also Assessment; Blood; Breast; Cancer, Biology; Cellular Aging: Telomeres; DNA Damage and Repair; Palliative Care; Prostate; Surgery in Elderly People.
Balducci, L., and Extermann, M. "Cancer and Aging: An Evolving Panorama." Hematology/ Oncology Clinics of North America 14 (2000): 1–16.
Cohen, H. J. "Oncology and Aging: General Principles of Cancer in the Elderly." In Principles of Geriatric Medicine and Gerontology, 4th ed. Edited by W. Hazzard. New York: McGraw-Hill, 1999. Pages 117–130.
Hunter, C. P.; Johnson, K. A.; and Muss, H. B., eds. Cancer in the Elderly. New York: Marcel Dekker, 2000.
Yancik, R., and Ries, L. A. G. "Aging and Cancer in America: Demographic and Epidemiologic Perspectives." Hematology/Oncology Clinics of North America 14 (2000): 17–23.
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