How long would cancer cells stay alive outside body (not preserved )in an hostile condition ?

Rather quickly. To survive any such cell requires a nourishing environment. They take nutrients from the host system. Without moisture & fuel they die after drying out or expending the limited energy stores they have on hand. Their cell walls begin to disintegrate.

How did the cancer cells get outside the body? Cancer cells in urine or feces would not be infective to anybody, even if the cells were alive for a few hours.