Scientists have discovered cancers that have been spreading like viruses for centuries among species of shellfish, a revolutionary discovery that could change the way cancer is treated in humans.
A study found two strains of an ancient form of cancer similar to leukemia that has been spreading silently among shellfish for centuries.

According to the study recently published in the journal Nature Cancer, scientists at the Wellcome Sanger Institute in the United Kingdom and the University of Santiago de Compostela in Spain collaborated with experts in several other countries to use DNA sequencing to examine the extent to which ancient cancers have silently spread among snails since ancient times.

Contagious cancer is just a fluke in the natural world, and occurs in a limited number of animal species. But the latest discovery in oysters raises the possibility that there are more similar forms of cancer that pose a potential threat to humans.

As far as scientists know, cancer can only be transmitted to humans in extremely rare cases. For example, there have been a few cases in which mothers passed cancer to their children during pregnancy.

Transmissible cancers have been sequenced for the first time in cockles, a type of edible saltwater shellfish that belongs to one of the oldest groups of animals on the planet.

Gastric cockle cancers are known as bivalve transmissible tumors (BTN).

Transmissible cancer cells float freely in the water like microscopic bacteria, are picked up by oysters, and multiply in their host, like leukemia, before escaping to attack others.

Dr. Alicia Brozos, co-first author, said in the study: “We have shown that there are two independent types of cancer that are transmissible, and we believe that there are many different types.

“Getting a broader view of the different types of transmissible cancers can give us more insight into the conditions necessary for tumors to develop and survive in the long term,” according to what was published by the “Russia Today” website.

The team preparing the study found that cockle tumors are largely genetically unstable and contain different numbers of chromosomes, which is unusual for cancers.

“Our study showed that the cells in these cockle tumors contain highly variable amounts of genetic material, which is very unusual compared to other types of cancer,” said study co-author Dr. Daniel Garcia Soto. “These cancers have undergone extreme chromosomal changes and ongoing epigenetic reorganization, perhaps for hundreds or thousands of years, which challenges the theory that cancers require stable genomes for long-term survival.”

The results indicate that these cancers are unlike any other transmissible cancer in animals, as a stable genome is not necessary for the survival of these transmissible cancers.