Leukemia-Like Cancer in Bivalves

The present review summarizes information available in the published literature on the distribution of disseminated neoplasia, or malignant leukemia (leukemia-like cancer), in populations of several bivalve species. This disease of marine Bivalvia has long been known; currently (with the development of molecular-genetic methods) its etiology is associated with retrotransposons that can be transmitted by horizontal gene transfer between different bivalve species. Transmission of retrotransposons, as well as neoplastic hemocytes or their clusters, is possible via seawater. The fact that the immune system of the recipient does not reject the neoplastic hemocytes is of particular interest. In some regions of the world, leukemia-like cancer causes serious economic damage to bivalve aquacultures. The development of methods to diagnose cancer in mollusks opens up broad prospects for their use in marine biology and can also be helpful in studying human malignant tumors.