Abstract B121: Dependencies between cancer and other major disorders of the elderly

B121

Today's preventive care strategies are oriented toward decreasing the risks of major health disorders (e.g., cancer, heart disease) treating them as rather independent. However, factors associated with increased vulnerability to one disease may, in principle, be protective against other pathology and even favor increasing total survival if the protective effect overweighs the detrimental one. In such situation, the prophylactic measure aiming at reduction of the risk of a particular disease (say, lowering blood cholesterol to prevent heart disease) may simultaneously elevate the risk of other disease (say, cancer) in case if this prophylactic measure affects these risks in opposite ways. While individual prophylactic plans should consider person’s and family history of particular disorders, a reasonable preventive strategy for the whole population would be targeting the minimal risk of death from all causes combined rather than the risks of separate disorders treated independently of each other. Studying potential dependencies between common diseases with high impact on mortality is, therefore, of high importance for both improving preventive strategies and ways to increasing human longevity. Recent studies suggest a number of underlying biological mechanisms for a possible correlation (positive or negative) between cancer and several other disorders. Chronic inflammation could be example of common pathogenetic factor in cancer and asthma which might favor their co-appearance in population. On the opposite side, the differential activity of apoptosis in tissues could be the factor potentially underlying negative correlation between cancer and heart or Alzheimer’s disease. It is, however, unclear how the risk of one disease will change in presence of other disease in real life. Knowledge of disease etiology and pathogenesis alone does not allow predicting behavior of respective incidence rates curves for sure. This is because the different disorders may have both the same and opposite risk factors and it is unclear which ones will overcome. Specific disease treatment (e.g., chemotherapy) may also modify body’s vulnerability to other pathologies, so that the risk of one disease may increase in presence of other one even if they initially had rather opposite predisposing backgrounds. In this study we address the following questions: What are relationships between risks of cancer and selected common disorders, including acute coronary heart disease (ACHD), asthma, and Alzheimer’s disease (AD), and How can current bio-medical knowledge about disease risk factors explain these relationships. We evaluated the risk of cancer in presence of each of the selected diseases, and vice versa, among 41,947 individuals aged 65+ from the National Long Term Care Survey (NLTCS) data linked to Medicare records. We found that cancer and ACHD as well as cancer and asthma are positively correlated, that is one disease appears among individuals with other disease more frequently than expected. Contrarily, cancer and AD are negatively correlated, suggesting trade-off between the effects of factors predisposing to these pathologies. A possible explanation involves differential effect of apoptosis on risks of cancer and AD. Other potential mechanisms of observed relationships among cancer and ACHD, asthma, or AD are also discussed.

Citation Information: Cancer Prev Res 2008;1(7 Suppl):B121.