I've wondered that myself. And for myself. I gather that it does take several years to go from early cancer cells to a tumor that's visible by MRI. But once th

I've wondered that myself. And for myself. I gather that it does take several years to go from early cancer cells to a tumor that's visible by MRI. But once there's a visible tumor, progression is much faster. And by the time you're clotting up and experiencing GI symptoms, you already have multiple metastases. But there's no specific blood test, as far as I know. So basically you'd need an annual MRI scan, I suspect. I guess that'd cost too much. Or maybe damage from the x-ray exposures would overall increase risk.