A few years ago I got testicular cancer. The information about the disease came in pieces: first all I knew was that there was a lump; then came the ultrasound, the CT scan, then biopsy of the testicle, then a second surgery to sample lymph nodes to which the cancer might have spread. At every step I would obsessively query my doctors for conditional probabilities: given what we'd just found out, what were the chance…
Also, just to jump on the train, if something is weird with your testicles, pain or lumps or whatever, go see a doctor. I waited longer than I should have and it probably made my treatment harder than it could have been.