Tumor cells spread canine cancer

A cancer in dogs is spread by the tumor cell itself, according to a study in this week's Cell. All cases of this cancer originated from a single cancerous cell in a dog or wolf ancestor hundreds of years ago, the researchers report."That means it's the oldest known cancer cell line known to science, much older than HeLa cells," senior author Robin Weiss of University College London told The Scientist.During the study, the authors sampled canine transmissible venereal tumor (CTVT) cells from dogs all over the world. They found that the tumors are genetically distinct from the host animals, but closely related to each other -- a finding that challenges current thinking that cancer cells are inherently unstable, and gather more mutations over time. CTVT is usually transmitted sexually between dogs but can also spread through biting, licking, or sniffing. Healthy dogs who develop the tumor often...