Agree, it totally depends on the type and stage of the particular cancer (different ones react differently). Some cancers may be "cured outright", others may have a much higher recurrence rate. The problem is drs can never guarantee it is "totally gone" from the body, ever. All they can do is say they think it's gone, and confirm that by checking vigilantly for a recurrence in the hope of catching it early if it happens. As time passes (esp after the "magic 5 year mark") it becomes statistically less and less likely that there will be a recurrence if there hasn't been one during that time, but even so doesn't rule out the possibility.

Probably best to discuss the specific situation with a dr if you can, as each individual's situation is different.