Infectious cancer cells found in clams and mussels have proved to be capable of leaping between individuals – and “shockingly” moving between species.
Scientists believe this raises the possibility of cross-species contamination and cancer becoming infectious in humans.
It was previously thought that catching cancer from another animal was extremely rare, but now there are findings from six different organisms in the world showing such evidence.
Molecular biologist at the University of Cambridge, Elizabeth Murchison, said: “We thought these things happen now and then in nature, but that this was a fluke. Now, the finding that these seem to be fairly widespread changes that outlook.”
One such case study is the Tasmanian devil population, which has been devastated by a contagious facial cancer spread by biting.
The latest work, conducted by Stephen Goff at Columbia University, found the first type of these cancer cells in an Atlantic mudflat clam.
Goff said: “We were forced to come to the conclusion that somehow this clone had spread from animal to animal in the oceans up and down the coast.”
There is no suggestion that humans would be at great risk as our immune system would attack any alien tissue that entered the body. However one case study showed an AID's patient who contracted cancer cells from a tapeworm due to his compromised immune system.
It is still unknown how the cancer cells are able to jump between individuals, Goff said: “It may just be that they’re pooping these cells into the ocean.”