Species focus – Sharks and cancer

I am a shark freak. I love them. I want to climb into a shark cage and see a great white up close. I read books about sharks, and I don’t just watch shark shows during Shark Week. Aside from some still prevalent fear of sharks and mindless person-eaters, one of the things that has affected shark survival the most is interest in eating shark cartilage as a cancer treatment.

Some how society got to believing that sharks don’t get cancer. Not true. Tumors are known in sharks as early as the mid 1800s. So aside from the fact that the basic premise is untrue, why exactly do we think that eating something will cure all our problems? I actually remember when I first got glasses, I knew carrots were good for your eyes, so I hoped that if I ate enough carrots my vision would improve. Imagine what we would eat if you got direct benefits from your food like that. I want to run faster, guess I’m eating cheetah tonight. I want to be able to change colour to camoflauge with my background, chameleon on the menu. Yeah, right.

But have we actually studied it, do we know that there is no actual benefit from taking shark cartilage to treat different forms of cancer? A study published in the Journal of the National Cancer Institute examined the use of shark cartilage in addition to chemotherapy and radiation to treat lung cancer: no benefit was found.

Recently Nature published an article detailing findings from the first project to sequence a shark genome. One of the findings that was particularly interesting was about their immune system. The shark in question is an elephant shark. What they found was that a key component of most vertebrate immune systems, the helper T cell is completely absent. This is incredibly interesting because helper T cells are largely responsible for identifying invading pathogens and alerting the rest of the immune system to mount a response. How do they deal with infection without these cells? Interesting avenues for further research.

There is still much to learn about sharks, to do that we need to help keep them around, and one aspect of that is getting rid of pseudo science like this so that sharks are seen as more valuable alive, than ground up in a bottle.