As chrisamiller says, cancer is generally not transmissible. One of the reasons cancer is so insidious is that a tumor is made up of the patient's own cells.

As chrisamiller says, cancer is generally not transmissible. One of the reasons cancer is so insidious is that a tumor is made up of the patient's own cells. Foreign cells, on the other hand, can generally be readily detected and destroyed by the immune system. The reason tasmanian devils can transmit cancer is that they're not genetically diverse enough to differentiate foreign cells from their own cells. But that's the exception that proves the rule: tasmanian devils are unusual in that they went through recent population bottlenecks that dramatically reduced their genetic diversity.