Physiological aspects of aging. Implications for the treatment of cancer.

The aging of the population has focused attention on the special needs of elderly patients. The increasing number of elderly people in the world's population has led to a parallel increase in the number of older cancer patients. Bias against older patients for screening and treatment of cancer exists, whereby effective therapies are withheld in the mistaken belief that these patients cannot tolerate them. Physiological changes which occur with aging include decreased cardiovascular performance, decreased haematopoietic tissue, a respiratory system which has been affected by life-long exposure to infection and toxins, decreasing renal function and a compromised nervous system. These changes have implications for drug toxicity such as possible increased sensitivity to cardiotoxins and increased haematological toxicity from myelosuppressive therapy. With the physiological decline in renal function with age, drug dosages must be carefully evaluated to avoid chemotherapy toxicity and its sequelae. Older patients may have increased sensitivity to oral toxicity, in particular, mucositis. There are also issues regarding tolerance of the older patient to radiation therapy. The haematopoietic growth factors and new antiemetics now available will allow chemotherapy to be administered with greater safety while maintaining quality of life. Overall, the healthy elderly are appropriate candidates for standard and experimental antineoplastic therapy. Careful assessment of end-organ function needs to be performed before a decision regarding the proper treatment regimen can be made. Clinical trials have rarely included the elderly, making data scarce. More research is needed in this age group.