This chapter discusses many of the general relationships of oncology and aging. It focuses on the epidemiological, basic etiological, and biological relationships between the processes of aging and neoplasia, and on the generalizable aspects of management of malignant disease in the elderly patient. This chapter discusses clinical management of individual malignancies only as an example of general principles. The approach to specific malignancies is covered in subsequent chapters related to the appropriate organ system.
It is now well recognized that cancer is a major problem for elderly individuals. It is the second leading cause of death after heart disease in the United States, and age is the single most important risk factor for developing cancer. Approximately 60% of all newly diagnosed malignant tumors and 70% of all cancer deaths occur in persons 65 years or older according to the NCI Surveillance. As illustrated in Figure 94-1, the total cancer incidence rises progressively through the middle years and then falls off in the later years. However, the age-specific cancer incidence rises progressively throughout the age range. Thus, while the rate of increase diminishes somewhat in the oldest age groups, and the rate actually falls slightly in the very oldest (perhaps a survivor effect), the overall risk for developing cancer is certainly greatest in the later years. Because the number of people in this country older than age 65 years is rising rapidly and the oldest of the old, that is, those older than age 85 years, are increasing at the greatest rate, geriatricians, generalists, and internists will be encountering increasing numbers of elderly individuals with cancer in their practices.
Comparison of the percentage of total cancer incidence and mortality by age with age-specific incidence and mortality. (Data from SEER Cancer Statistics Review: 1973–1994. Bethesda, MD: National Cancer Institute, 1997.)
The median age range for diagnosis for most major tumors, common to both men and women, is 68 to 74 years; the median age range at death is 70 to 79 years. The overall pattern for the incidence of age-specific cancer shows a rise with age; overall, 60% of cancers occur in those age 65 years or older (Table 94-1). This is not uniform for individual cancers and in some malignancies, there is an apparent decrease in incidence in people older than age 80 years. This may be a result of a number of factors, including underreporting or natural selection, which would allow the less-cancer-prone population to survive. However, cohort effects may have the most significant impact. For example, age-specific annual cancer incidence rates from the SEER Program indicate a fall in incidence in the oldest age groups for both prostate and lung cancer. This changes when the data are corrected for certain known risk factors. For prostate cancer, when only men are considered in the base population at risk, the incidence continues ...