Your body produced cancer because your immune system can not recognize cancer cells, which are our own cells with faulty DNA. Faulty cells are produced by the billions in every body, and the immune system destroys them before they form a tumor.
If your cancer was caught early and was caused by sudden exposure to cancer causing incident such as over-exposure to ultra-violet causing skin cancer, it is possible your immune system is still functional. And the cancer was local and excised by treatment.
What is really insidious about cancer is that it can start in some place in body, and there are no symptoms. If cancer is growing in Liver, it takes months and years before symptoms show up. There is no way to detect early cancer without constant biopsies in every organ.
I am not trying to sound ungrateful but in this case I’ll believe my former oncologist. ;-)