[Is cancer a transmittable disease?].

A direct, horizontal and natural transmission of neoplasic cells has only recently been accepted by the biomedical community. There are three known examples in mammals: the Tasmanian Devil Tumor Disease, the Canine Transmissible Venereal Tumor and a similar disease in Sirian Hamsters. These diseases are not anecdotic cases only, but provide support for the cancer clonal evolution hypothesis.