Recently, I finished another in my series of science fiction books entitled, Catching Cancer. It makes for some fascinating reading but it is not as far fetched of an idea as you might think. In animals, there are three examples of transmissible cancers: one in dogs, one in the Tasmanian devil and one in the Syrian hamster. The genome of these cancers is stable enough to be transmitted to another host. It was because of their transmission that it was thought that these diseases were caused by the transfer of cancer causing viruses, similar to the transmission of cervical cancer caused by HPV, the human papilloma virus. Sexually transmitted cancer in dogs (CTVT) was experimentally transplanted between dogs way back in 1876. Dogs have been colonized worldwide ever since, presenting the oldest known malignant cell line in continuous propagation.