Cancer is closely associated with ageing: 60% of all cancers occur in individuals 65 and older, and 70% of all deaths occur in this age group. The aging population becomes increasingly vulnerable to cancer partly due to the considerable time required for tumor promotion and growth. 2
The aging cell accumulates defects in its DNA molecules. 5 2Since DNA is the source of genes, these defects can result in the formation of defective proteins that favor carcinogenesis. Although most of cellular DNA is associated with the nucleus of the cell, defects in mitochondrial DNA may actually play a greater role in carcinogenesis. 3 Mitochondria are subcellular structures that are essential for energy production. This energy production results in the formation of reactive oxygen species as byproducts. These reactive oxygen species cause mutations in mitochondrial DNA resulting in mitochondrial dysfunction. This dysfunction causes oxidative stress leading to carcinogenesis by several processes including inhibition of apoptosis (programmed cell death), activation of oncogenes (cancer-causing genes), and inactivation of tumor suppressor genes.
The aging cell has a reduced capacity to divide and proliferate. These changes may promote tumor growth by inhibiting apoptosis and by releasing tumor growth factors and metalloproteinases. The aged cell also has a longer time exposure to the effects of carcinogens (cancer-causing agents in the environment).
Treatment of the older cancer patient
As a whole, cancer treatments in older patients are as effective as in younger patients. 4Advances in surgical procedures and anesthesia have made surgery a safe option for older patients, although the post-operative recovery period may be prolonged. Radiotherapy should be used in moderation, since there is a greater risk of inflammation of mucosal tissues, causing dysphasia (difficulty in swallowing) and diarrhea.
Changes in pharmacology (drug interactions in the body) can result in changes of drug dosages for the elderly patient when chemotherapy or the newer biological or targeted therapies are used. Reduced absorptive capacity of the intestinal tract might require a larger dosage when oral administration is used. Most other characteristics of the ageing body require a reduction of drug dosage to prevent toxicity. Reduced kidney function causes reduced excretion of drugs. Reduced volume of blood constituents such as albumin and hemoglobin can result in higher concentrations of drugs in the fluid portion of blood. Reduced intracellular breakdown of drugs could result in the accumulation of drugs.
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