Reacción a "A transmissible melanoma-type cancer has been discovered in fish, the fourth known contagious tumor among animals"

"I found the study fascinating and high quality with results presenting of immediate interest to conservation and evolutionary biologists, disease epidemiologists and cancer researchers.

The article addresses a very important topic, the discovery of a fascinating infectious disease, a transmissible cancer, in a new vertebrate host, a freshwater benthic fish. Transmissible cancers (that have been proposed to be new parasitic life forms) have so far only been discovered in two vertebrate groups, in dogs and Tasmanian devils. Recently several transmissible cancers have been discovered in marine ecosystems, where their presence is becoming concerning as they can wipe out populations of ecosystem engineers, i.e. bivalves. Studies investigating these infectious diseases are therefore urgently needed. The study highlights the importance of surveying other ecosystems, like freshwater bodies (that may or may not be exposed to pollution) to discover, mitigate and manage the emergence of these novel parasitic life forms.

[Regarding potential limitations] Sampling of additional populations of fish would be needed to discover the geographic spread, the age and the origin of this clonal cancer, as well as its impacts not only brown bullhead populations but also on the ecosystem they inhabit".

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?

"Cancer cells passed from one individual to another are normally eliminated by a competent mammalian immune system. There is no need for public concern; tumor transmission between humans is exceedingly rare.  Rare instances of human‑to‑human cancer transmission have been documented, including maternal–foetal transfer (0.1% of pregnancies), donor‑derived cancers in organ transplant recipients (0.04% of solid organ transplant recipients), and a handful of accidental laboratory or surgical exposures. Nevertheless, humans have a highly efficient immune system that is capable of recognising foreign cells, like transmissible cancer cells from fish, the likelihood of transmission from bullheads to humans therefore is as close to zero as it gets".