Can Sharks Get Cancer? The Truth Behind the Shark Cancer Myth
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| SHARKS GET CANCER?! |
Can Sharks Get Cancer? The Truth Behind the Shark Cancer Myth
You may have heard an astonishing claim: “Sharks never get cancer.”
It sounds believable because sharks have survived for hundreds of millions of years and possess unusual biological traits. This idea even helped create a global market for shark cartilage supplements.
But there is one major problem:
Sharks can—and do—develop cancer.
The belief that sharks are immune to cancer is not an amazing scientific discovery. It is one of the most persistent animal myths ever spread.
Where Did the Shark Cancer Myth Begin?
The myth became widely known after the 1992 publication of a book titled Sharks Don’t Get Cancer. It promoted the idea that shark cartilage could prevent tumors from growing.
Sharks have skeletons made primarily of cartilage rather than bone. Researchers had discovered that cartilage contains substances capable of affecting angiogenesis—the process by which new blood vessels form.
Because growing tumors need blood vessels to receive oxygen and nutrients, some people made a dramatic leap in logic:
If shark cartilage can restrict blood-vessel formation, perhaps sharks cannot develop cancer.
However, having cartilage does not make an animal immune to cancer. Scientists have documented different tumors in sharks, including malignant cancers.
Scientists Have Found Cancer in Sharks
Cancer occurs when abnormal cells grow uncontrollably, invade surrounding tissue, or spread to other parts of the body.
Sharks are made of cells, and their cells can also develop harmful mutations.
Researchers and veterinarians have recorded tumors in multiple shark species. A 2024 veterinary report, for example, described primary liver tumors in three adult female bamboo sharks. The diagnoses included biliary adenocarcinoma and other liver neoplasms.
These documented cases directly disprove the claim that sharks never get cancer.
Cancer may appear to be uncommon in sharks, but that does not mean they are immune. Wild sharks are difficult to monitor throughout their lives, and sick animals may die or be eaten before scientists can examine them.
As a result, the true cancer rate among wild shark populations remains difficult to determine.
Are Sharks Better at Resisting Cancer?
This is where the story becomes more interesting.
Sharks may possess biological defenses that help them survive disease, repair DNA, or control abnormal cell growth. Their immune systems and long evolutionary history make them valuable subjects for scientific research.
However, “possibly resistant” and “completely immune” are very different claims.
Scientists can study shark biology to search for useful molecules or mechanisms, but those discoveries must still pass laboratory testing and human clinical trials.
An animal’s natural defense does not automatically become a safe or effective medicine when consumed as a supplement.
Does Shark Cartilage Treat Human Cancer?
There is no reliable evidence that eating powdered shark cartilage cures human cancer.
Shark cartilage attracted attention because laboratory research identified substances that might interfere with angiogenesis. But promising activity in cells or animals does not guarantee that a substance will work inside the human body.
A large randomized clinical trial examined AE-941, a shark-cartilage-derived product, in patients with advanced non-small-cell lung cancer. Adding it to standard chemoradiotherapy did not improve overall survival.
The National Cancer Institute’s cartilage review also states that the FDA has not approved shark cartilage as a treatment for cancer or any other medical condition.
Relying on unproven supplements can be dangerous if patients delay or replace evidence-based medical care.
Anyone undergoing cancer treatment should speak with a qualified healthcare professional before taking supplements because some products may cause side effects or interact with medications.
The Environmental Cost of the Myth
The shark cancer myth did not only mislead people—it also harmed sharks.
Demand for shark cartilage products encouraged the harvesting of sharks for supplements. Sharks generally grow slowly, mature late, and produce relatively few offspring. These characteristics make many species especially vulnerable to overfishing.
Removing large predators can disrupt marine food webs and affect the balance of entire ocean ecosystems.
In other words, a false health claim created consequences for both human patients and marine wildlife.
Why Does This Myth Still Survive?
The claim continues to spread because it combines several powerful ideas:
Sharks are ancient and mysterious animals.
Cartilage contains biologically active compounds.
Cancer is frightening, so people naturally hope for a simple cure.
“Sharks never get cancer” is easier to remember than a complicated scientific explanation.
But memorable claims are not always accurate.
A compound found in an animal might inspire future research, yet that does not prove the animal is disease-free or that consuming its tissue will cure humans.
The Real Lesson Hidden Inside the Myth
Sharks are not cancer-proof superheroes. Like other animals, they can develop tumors and malignant cancers.
Still, their biology may hold valuable scientific clues. Studying how different animals suppress tumors, repair DNA, and respond to disease could eventually help researchers understand cancer more clearly.
The real discovery is not that sharks never get cancer.
It is that even an animal that survived multiple mass extinctions cannot completely escape the biology of cancer.
Sources
Primary Hepatic Neoplasia in Three Adult Bamboo Sharks – PubMed
Cartilage and Cancer Treatment Overview – National Cancer Institute/NIH
Clinical Trial of Shark Cartilage–Derived AE-941 – Journal of Clinical Oncology
This article is for educational purposes and is not a substitute for professional medical advice.
Key Takeaways
- Sharks can develop both tumors and malignant cancers.
- Scientists have documented cancer in several shark species.
- The myth became popular partly because of shark cartilage research.
- Shark cartilage has not been proven to cure human cancer.
- The myth has contributed to misleading health claims and pressure on shark populations.
FAQ
1. Can sharks really get cancer?
Yes. Scientists and veterinarians have documented benign tumors and malignant cancers in sharks.
2. Why did people believe sharks were immune to cancer?
The belief grew from research into cartilage and angiogenesis, combined with exaggerated claims that shark cartilage could prevent tumor growth.
3. Can shark cartilage cure cancer?
There is no reliable clinical evidence that shark cartilage cures cancer. It has not been approved by the FDA as a cancer treatment.
4. Is cancer rare in sharks?
It may be reported less frequently, but scientists do not have enough data to determine the true cancer rate in wild sharks.
5. Should cancer patients take shark cartilage supplements?
Patients should not use shark cartilage as a replacement for established treatment. They should consult their healthcare professional before taking any supplement.
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