Cancer & Ageing

Is cancer a distinct disease? Or is cancer a consequence of biological ageing? Or is cancer the same as ageing - simply, one of multiple manifestations (phenotypes) of that degenerative process?

The association of cancer with ageing is not just an abstract, intellectual interest; it has critical, practical considerations. Billions of dollars are spend annually for the treatment of cancer as a particular disease, and after decades of medical "advances", there has been virtually no progress. Further, comparably large sums of money (public and private) are allocated to cancer research; and most bio-tech start-ups reference some type of cancer as one of their therapeutic targets, because that is where the money is. However, if cancer is caused by ageing or if it is one manifestation of ageing, then treating it as a specific disease will never have much merit unless ageing is cured first. Even if a cure specifically for cancer were to be found, it would be of only marginal efficacy and have little life-prolonging effect because the ageing process would continue to proceed or even be accelerated by therapeutic modalities.

I have come to believe that cancer and ageing are integral; and here is a review of some of the evidence in that regard. First, the mortality of the general population, which is said to be governed by the ageing process, is presented and then compared with mortality from cancer - the comparative survival curves are identical. Indeed, the disease-specific survival curves for all of the major chronic diseases are identical to the ageing of the general population. Finally, if cancer were caused by ageing, then the slowing of ageing should result in a lowering and deferment of the incidence of cancer - and it does!

If you chart the survival of a general population which dies from all causes of mortality (e.g., heart disease, cancer, stroke, diabetes, homicide, accident, infections, etc.), then you see the following survival curve.

If you compare the survival curves over the last 100 years, you see a gradual progression toward increased average
life-expectancy (from about 49 to 79) without any real change in the maximum longevity.

Over the last century, this "squaring" or optimization of the
survival curve has been caused by an increased standard of living, nutrition, a host of public health measures and, more recently, medicine. Because the benefits from this environmental improvement have reached a cul-de-sac, it is held that the population now experiences ageing and dies mostly from the chronic diseases. But the issue here is whether the chronic diseases are separate pathologies and distinct from ageing or if they are different expression of that general degenerative process.

For example, if you were to take everyone who died from
cancer and treat that group as if it were the entire population (i.e., 100% of the population died from cancer), then you get the following survival curve.

If you compare the survival curve of the total population which dies from all causes of mortality and which ages with the strictly cancer population, you see the following.

In other words, there is virtually no difference between the
survival curve of the general mortality population and the cancer population. Indeed, when we draw survival curves for all of the major chronic diseases and compare those with the general mortality population, we see that they are indistinguishable from each other.

In terms of the survival curve, there is no way to distinguish
between the chronic diseases and ageing; and it is essentially
pointless to invent treatments or even cures for cancer and the
other chronic diseases unless and until ageing is cured. As a side comment, the theory of the monoclonal origin of atherosclerotic lesions the atherosclerotic lesion holds that the "plaque" which causes coronary artery disease is a type of benign tumor (See MEDLINE retrieval); and if that is true, then neoplasia, cell mutations, or cancer constitutes some 60% of all chronic diseases.)

If this hypothesis about cancer being integral with the ageing process has merit, then techniques which slow ageing should also lower or defer the incidence of cancer; and in fact that happens.

It is generally accepted that caloric restriction slows ageing and since the 1940's it has been repeatedly observed and reported that caloric restriction also lowers and defers the incidence of all chronic diseases - notably cancers (Tannenbaum A. The dependence of tumor formation on the composition of the calorie-restricted diet as well as on the degree of restriction. Cancer Res. 5:616-625, 1945).

"Restriction in food intake imposed continuously throughout the postweaning life of the rat impressively reduced the incidence, rate of occurance, and risk of tumors.... Among the histoligically classified tumors in the chronically underfed rats, the reduction in risk was remarkably uniform and exceed 90% for the greater number of tumor types." (page 1099 below.)

Ross MH and Bras G. Lasting Influence of Early Caloric Restriction on Preval- ence of Neoplasms in the Rat. J. Nat. Cancer Inst. 47: 1095-1113, 1971.