I've been discussing advances in cancer research a fair bit over the past couple of months. Cancer is a big, bad part of the aging process; a haywire form of uncontrolled biochemical rot in the gears of your body. It's waiting for all of us if we manage to engineer the medical technology to evade heart disease, neurodegeneration and all the other failure modes of age-damaged biochemistry that kill before cancer can.
Here is a question for the floor: to what degree is a robust cancer cure sufficient for a future of ongoing, step by step healthy life extension leading to the defeat of death by aging?
What do I mean here? By a robust cancer cure, I mean a foreseeable level of medical technology whereby cancer is neither fatal nor greatly expensive to deal with in the degree to which it occurs in the old today. It can be detected early, eliminated in any but the latest of stages, and doing so will not dramatically increase the patient's expenditures on healthcare. I envisage technology based on microarray scans of blood for the earliest signs of cancer, and targeted, highly efficient therapies capable of eliminating cancer cells without damaging healthy systems in the body - the widespread technology base of 2015 to 2025, give or take a few years, in other words.
By "sufficient" I mean this: if ever more sophisticated refinements on the above themes are all we have to work with, would that be enough to stave off cancer for almost all people if other first generation rejuvenation technologies - in combination with general improvements across the board in medical technology - increased life span by two or three decades?
We envisage healthy life spans to increase in steps; a old person taking advantage of each new step might beat the curve, a little rejuvenation at a time, to live into an age in which aging was truly defeated. The first step, consisting of first generation attempts at most of the repair technologies outlined in biomedical gerontologist Aubrey de Grey's Strategies for Engineered Negligible Senescence (SENS), might plausibly provide a couple of decades of additional healthy life. That would mean a couple of decades in which medical science can further advance and improve - and so on, a step at a time.
The risk of cancer in any tissue increases with age - and as for most failing machines, quite dramatically so in later life. This stems from underlying changes in biochemistry and the simple rules that determine failure rates in machinery based on gradual wear in component parts - possibly the shortening of your telomeres, possibly damage to stem cells, possibly something else, possibly all of the above. Is it good enough to have a good after-the-fact cure on hand when the risk of occurance is increasing enormously with each passing year? Is there a point past which a good therapy is just overloaded by sheer weight of new cancer bursting from your cells, and where does that point occur?
Ultimately, we would want to change our biochemistry so as to prevent cancer from occuring at all. Like all projects aiming to safely re-engineer a very complex system, this will be challenging indeed - but it will get easier with time. At what point will we need to have absolute cancer prevention in hand to beat the curve of aging, and thus remain alive and in good health to take advantage of the next anti-aging technology in line? At what point does a cure for cancer fail us?