There's been some talk going around about DCA (dicholoroacetic acid) for the past few years regarding its anti-cancer potential. While a lot of the talk is about as well researched as your standard email chain letter, the stuff seems to have some effectiveness in very preliminary human trials.
The philosophy behind it is sound. While "Cancer" is actually many different diseases, 60-90% of cancers exhibit what's called the Warburg Effect
where they can't produce energy aerobically using oxygen, only anaerobically through glycolysis (basically lactic acid fermentation.)
By forcing all cells to produce energy using oxygen (anaerobically) it's possible to selectively target cancer cells. Those cells that do re-activate their aerobic capacity via the mitochondria also 'turn back on' the cell's "self destruct mechanism" call apoptosis making them easier to kill.
The thing is, dicholoroacetic acid is just chlorenated vinegar and there's a fair bit of literature that explores using other molecules to reduce glycolysis in animals that are to be slaughtered for meat, since meat with high levels of lactic acid in it is not as choice.
I'm thinking of occasionally adding calcium citrate and some resveratrol as a pre-workout supplement. Citrate also helps prevent glycolysis and is very well tolerated. This may push me to aerobic exercise earlier and prevent me from working out as hard and getting a less good workout. But I'm wondering if it might also help slow the growth of any latent cancer cells while they're still small. Resveratrol upregulates p53 which is invovled in apoptosis. (And also, oddly, seems to increase aerobic capacity.)
Autopsies of 50 year olds often find small cancers that were subclinical. So it seems reasonable to work on prevention.