The Myth

Sharks, the apex predators of the deep blue, are often rumored to be immune to cancer. This myth paints sharks as invincible ocean warriors who laugh in the face of disease while munching on seals. Popular culture and pseudoscience have perpetuated this belief, suggesting that studying sharks might unlock the secrets to curing cancer in humans. While it sounds cool enough to be the next superhero origin story, the idea that sharks are impervious to cancer is, quite literally, a fish tale.

Origin

The myth that sharks don’t get cancer likely originated in the 1970s when the hunt for miraculous cancer cures led researchers to explore uncharted waters. A key moment was the publication of Dr. John Prudden’s studies, which suggested that shark cartilage might have anti-cancer properties. This claim gained traction despite its shaky scientific foundation. By the 1990s, the idea snowballed into a full-blown myth, thanks to books like Sharks Don’t Get Cancer by I. William Lane.

Adding to the lore was the allure of sharks as ancient, unchanging creatures—nature’s bad boys who’ve survived for hundreds of millions of years. If they’re so good at survival, surely, they’ve cracked the code to evade cancer, right? Cue the rise of shark cartilage supplements, marketed as cure-alls for everything from arthritis to cancer. (Side note: If you also believe knuckle cracking causes arthritis, you might want to check my other blog on that myth.)

What’s truly fascinating is how pop culture latched onto this idea. Movies and TV shows occasionally referenced sharks as untouchable by disease, solidifying their mythical status. This is a classic case of pseudoscience meeting marketing hype—a cocktail that’s led to countless sharks being hunted for their cartilage.

The Science

Let’s dive into the science (pun intended). Do sharks get cancer? Yes, they absolutely do. While sharks possess some unique biological traits, such as impressive immune systems and rapid wound healing, they are not immune to cancer. Researchers have documented various types of tumours in sharks, including chondrichthyan fishes like rays and skates, which share similar biology.

So why the confusion? Sharks’ skeletons are primarily made of cartilage, which contains fewer blood vessels and may slow the growth of certain cancers. This feature, however, is not exclusive to sharks. Scientists have found no conclusive evidence that cartilage alone offers immunity to cancer. Furthermore, human cartilage behaves differently from that of sharks, so applying this logic to us is flawed.

Interestingly, the notion that alcohol warms you up is another great example of how misconceptions thrive. (Spoiler: It doesn’t actually warm you; it just makes you feel warm while it’s stealing your body heat), Similarly, the “sharks don’t get cancer” myth clings to one kernel of truth and spins it into an ocean-sized misconception.

Evidence

Scientists have studied shark biology extensively to understand their resistance to diseases, including cancer. However, the results are far from supporting the myth. For instance, a 2013 study published in BMC Genomics explored the genome of the great white shark. Researchers found some genetic adaptations linked to wound healing and DNA repair, which could potentially explain their resilience to some diseases. However, none of these traits rendered sharks’ cancer-proof.

Moreover, sharks’ reputation as immune to cancer has led to the exploitation of their cartilage for pseudo-medical products. Multiple studies have evaluated the effectiveness of shark cartilage supplements in treating cancer. The National Cancer Institute conducted trials on such supplements and found no evidence that they slowed cancer progression or improved survival rates. In fact, overharvesting sharks for cartilage has harmed marine ecosystems while providing zero benefit to human health.

The “sharks don’t get cancer” myth shares a common trait with other myths: it’s stubborn. Even as scientists produce studies debunking it, public belief persists. Perhaps it’s the allure of imagining sharks as indestructible forces of nature that makes this myth so sticky. But, like all pseudoscience, it falls apart under scrutiny.

Conclusion

Sharks may be apex predators, but they’re not invincible. The idea that they’re immune to cancer is a fascinating but false narrative born from bad science and relentless marketing. While sharks have unique biological traits, they’re not cancer-proof—just like alcohol doesn’t actually warm you up, and cracking your knuckles won’t doom you to arthritis. Myths are fun to imagine, but science reminds us that even the fiercest creatures have vulnerabilities. Let’s leave the pseudoscience in the deep and focus on protecting these magnificent creatures from threats far more real than cancer.