Do any animals living in saltwater acquire cancer?
Yes they do. The idea that sharks don’t get cancer, along with the fact that they have a high proportion of cartilage in their bodies, led William Lane, to author of Sharks Don’t Get Cancer, to decide that shark cartilage could prevent/cure cancer tumours in humans. In fact sharks can and do get cancer, even in their cartilage; but Lane’s pseudoscience is still being promoted by people unscrupulous enough to seek to make money out of desperate and vulnerable people by selling them shark cartilage pills. Gary Ostrander and colleagues from Johns Hopkins University have detailed more than 40 published examples of tumours in sharks, some dating back to the 1800s. And so far a total of 8 uncontrolled trials and 5 controlled trials have produced no evidence that shark cartilage is effective against cancer (the most recent study, by the American Cancer Institute, found it to be ineffective for lung cancer patients).
