Re: Depression as a Risk Factor for Cancer: Renewing a Debate on the Psychobiology of Disease

regarding the very fine study by Penninx et al. (2), suggested that three areas of follow-up research would be indicated to further delineate the association be-tween depression and cancer. One of those recommendations was to extend the study of a younger population, be-cause it may be that the mechanisms re-sponsible for the relationship between depression and cancer are related to the aging process. I don’t anticipate that a negative study in younger patients would justify the conclusion that aging is the cause of the association between depression and cancer death that was found in the study by Penninx et al. (2). Cancers in general have a long latency. As pointed out by Croyle, stress and depression have been associated with the causation and accel-eration of cardiovascular disease. Car-diovascular disease tends to cause death at a younger age than does cancer. Therefore, one would have a common risk factor (for cardiovascular disease and cancer) and a competing cause of death (from cardiovascular disease and cancer), which would confound any epi-demiologic study where death from can-cer is in part or in whole an end point. I think the main value of studies in younger patients would be to determine whether stress and depression can have an effect on the recurrence or progres-sion of cancer. The fact that such an as-sociation is being found more frequently (3) would lend further credence to the study by Penninx et al