Are sharks immune to cancer?
In short: No. Sharks get cancer. Tumours have been documented across multiple shark species; the immunity claim grew from overstated marketing of cartilage supplements, not from oncology data.
By the WARN Research & Conservation TeamChecked against IUCN Red List & CITES sourcesLast updated
- Key takeaways
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- Sharks are not immune to cancer.
- The myth was amplified by cartilage-supplement marketing.
- Accurate shark biology matters for both medicine claims and conservation.
Museum and veterinary records include cancers in sharks and rays. The rate may differ from some mammals, and shark cartilage was once promoted as a cure based on the idea that cartilaginous skeletons somehow block tumours — that leap was never justified by controlled evidence in people.
Lower reported rates in wild sharks, where they occur, can reflect sampling bias: sick wild animals are hard to find, and many specimens are never examined for internal tumours.
Repeating the immunity myth has real costs. It drove a market for shark cartilage products that encouraged fishing pressure without delivering the promised medical benefit.