Elizabeth Murchison
"It’s a very exciting paper which clearly shows, for the first time, that a type of melanoma in brown bullhead catfish is a transmissible cancer, spread by the transfer of living cancer cells themselves.
Transmissible cancers are an unusual type of disease in which the cancer cells themselves are infectious agents and spread between individuals; there are no viruses or other microbes involved in the spread of disease. Until now, transmissible cancers have only been found in dogs, Tasmanian devils, and several species of marine bivalve molluscs, including clams, cockles and mussels. This paper reveals for the first time that transmissible cancers also occur in some species of fish. This suggests that transmissible cancers may not be as rare in nature as was previously thought.
There are not important limitations, the paper is very clear and straightforward".
Considering potential public concern: are there cases of tumor transmission between humans? How frequent are they? Could any mechanisms similar to those being described in some animals occur in humans?
"There are rare cases of cancer transmission between humans, but in almost all of these cases cancer cells only spread between two people, and not further. These cases mostly involve organ transplants (accidental transplantation of organs from undiagnosed cancer patients), pregnancy and childbirth (e.g. mother to foetus transmission through the placenta), and accidents (e.g. surgical accidents in which a surgeon injures themselves with a scalpel blade contaminated with cancer cells). Although unlikely, there is potential for a transmissible cancer that spreads through populations, similar to those observed in animals, to arise in humans. However, it should be strongly emphasised that such transmissible cancers have not been observed in human populations and the risk of one arising is low".