Epistemic status: idea I got in college biology nearly ten years ago. My memory of the relevant biology may not be perfect.
Recently, Sarah Constantine has been writing some posts on cancer treatments and how we might create better ones. This has reminded me of some thoughts I’ve had for awhile on cancer cures and life-extension, and why I’m quite pessimistic about the prospects for them.
(This is not a direct reply to Sarah–she hasn’t finished her post series yet, so it’s hard to evaluate her arguments.)
Basically, cancer and aging seem to be two sides of one coin. Cancer is typically described as cells growing out of control, but in a sense cancer is more fundamentally about cells not dying when they should. Conversely, a lot of aging involves slow cell death throughout the body. This means trying to solve both problems is a potentially delicate balancing act.
For example, telomeres seem to play an important role in aging. I won’t get in to the technical details, but basically a lot of people think telomere elongation is promising as an aging treatment. Unfortunately, it turns out that willy-nilly telomere elongation causes cancer.
Conversely, well, I probably don’t need to tell you that radiation therapy and chemotherapy often suck. Cancer cells aren’t alien invaders from outside your body, they’re your own cells gone bad, and how exactly they go bad can vary a lot. So it’s hard to kill cancer without killing some cells you don’t want to kill.
In other words, medicine is very broadly about making sure your cells don’t die when you don’t want them to. Cancer, however, is about cells not dying when you want them to (until you and all your cells are killed by the cancer). This is an example of the general problem with false positives vs. false negatives. The hard thing isn’t reducing one or the other–it’s reducing one without increasing the other.
Similarly, there’s nothing actually difficult about killing cancer cells–cyanide should do the trick. And maybe preventing aging-related cell death is just a matter of throwing telomerase at the problem. Doing both at the same time, however…
If this model is right, solving cancer and aging will likely make solving the problem of AIDS look trivial by comparison. For a long time, AIDS was the big scary disease we couldn’t do anything about, but nowadays antiretrovirals are pretty effective and more recently we’ve gotten good AIDS prevention drugs. But AIDS was easy–we never had to worry about making a person’s viral load too low.