Cancer can spread between shellfish species, study finds

We typically don’t think of cancer as a disease we can catch from another person, but that isn’t necessarily the case for animals living on the sea floor.

According to a new study in the journal Nature, cancer can spread among multiple species of shellfish.

The study showed that in quite a number species of bivalves, including mussels and clams, cancer cells from infectious cells have propagated from animal to animal through sea water. The cancer, referred to as disseminated neoplasia, is a leukemia-like illness that affects bivalves in many parts of the planet.

The rarity of contagious cancer

One-to-one transmission of cancer cells is quite uncommon. Up to now, the phenomenon had only been identified in two types of mammals.

In 2015, the same team behind the new study discovered a third instance of cancer transmission in the soft shell clam (Mya arenaria) after originally suspecting the root cause behind the cancer cluster was a virus.

The team then considered if cancers in other mollusks are also brought on by contagious cells. To figure this out, the study team analyzed the DNA of cancers and normal tissue from mussels (Mytilus trossulus), cockles (Cerastoderma edule), and golden carpet shell clams (Polititapes aureus) gathered from the coasts of Canada and Spain.

In each species, the scientists uncovered the cancers were brought on by separate clones of cancer cells that were genetically unlike their hosts. They also discovered that in one species, the carpet shell clam, the contagious cancer cells originated from an associated but distinct species. The scientists determined that this cancer was as a result of cross-species transmission.

“Now that we have observed the spread of cancer among several marine species, our future research will investigate the mutations that are responsible for these cancer cell transmissions,” study author Stephen Goff, a biochemistry professor at Columbia University Medical Center, said in a news release.


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