Can a tumor become a new form of life?

This is the freaky but serious question that arises from a new study in the journal Cell. Scientists from London and Chicago have studied a peculiar cancer that afflicts dogs, known as canine transmissible venereal tumor (CTVT) or Sticker’s sarcoma. It is a cancer of immune cells called histiocytes, and dogs typically develop grapefruit-sized tumors that disappear after a few months.

Some scientists have suggested that Sticker’s sarcoma can be transmitted from dog to dog, either by mating or by licking or touching a tumor. They noted that the tumor cells appeared to share a unique genetic marker. But skeptics noted that virus-like particles are often found in or around Sticker’s sarcoma.