That's because before you're diagnosed with cancer, you're just sick with "something," or you're just not sick from it yet. I don't know a lot of people who get a cancer diagnosis, without having symptoms first. Hell, that's the biggest issue with cancer, by the time you have symptoms, it's often too late. My grandmother died in her sleep from "natural causes". She was 81. There was no autopsy, but, she was an organ donor, and they thought they could salvage her kidneys and liver. Regrettably, they found a mass of tumors in her kidneys. The transplant surgeon noted that based on the tumors and her blood work, she most likely died from a transitional cell carcinoma, the symptoms previously misdiagnosed as a persistent urinary tract infection.