Dima www.PHOTO-123.com/Shutterstock.com

Could tattoos be the secret weapon in the fight against skin cancer? It might sound incredibly unlikely at first, but new research suggests there’s more to tattoo ink than meets the eye, especially when it comes to melanoma risk.

For years, people worried about the possible health dangers of tattoos. But new research suggests something surprising: people with multiple tattoos appear to have less melanoma, not more. However, before anyone rushes to the tattoo parlour for cancer prevention, it’s crucial to take a closer look at the fine print because every study has its flaws, and this one is no exception.

Researchers in Utah – the US state with the highest melanoma rates – studied over 1,000 people. They compared melanoma patients with healthy people to see if tattoos, especially extensive ones, affect cancer risk.

The results suggested that people who’d had multiple tattoo sessions or possessed several large tattoos actually experienced a reduced risk of melanoma. In fact, the risk was more than halved.

This was a striking finding, especially given the longstanding concerns about tattoo inks, which contain chemicals that – in other settings – can be harmful or even carcinogenic. Scientists have previously worried that introducing foreign substances into the skin could promote cancer development.

Extensive recent research has in fact linked tattoos to a type of cancer called lymphoma. But this broad population-based study did not support these fears for melanoma.

Why the results might be misleading

Yet the evidence comes with a number of critical caveats. The first and perhaps most significant issue was the lack of data about key melanoma risk factors, which is essential for drawing reliable cause-and-effect conclusions.

Important risk factors such as sun exposure history, tanning bed use, how easily people sunburn, skin type and family history of melanoma were only recorded for people with cancer – not for the healthy people in the study. Without this information, it’s impossible to tease apart whether the observed lower risk in tattooed people actually stems from the tattoos themselves, or whether it’s merely a byproduct of other lifestyle differences.

Woman lying on a tanning bed.
Tanning bed use was only recorded for people with cancer. Josep Suria/Shutterstock.com

Another issue lies in something called behavioural bias. Tattooed participants were more likely to report riskier sun habits, such as indoor tanning and sunburns, although here the apparent “protection” of multiple tattoos remained even after adjusting for smoking, physical activity and some other variables.

However, data on key risk factors for melanoma, such as sun protection behaviour and the use of sunscreen, weren’t available across both groups. This raises the possibility that the supposedly protective effect might actually be a result of unmeasured differences – perhaps those with many tattoos are more likely to use sunscreen or avoid sun exposure to protect their body art.

Adding further complexity, the response rate among melanoma cases was only about 41%, meaning that most people with melanoma didn’t answer questions about it, which is relatively low, though typical for studies using surveys like this. This could create what’s called selection bias. If people who answered the survey were different from those who didn’t, the results might not apply to everyone.

No information was collected on where the tattoos were located, so we don’t know if they were on sun-exposed or covered areas of the body – an important distinction since ultraviolet light is a major risk factor for skin cancer. In fact, recent research suggests air pollution may protect from melanoma and it does this by filtering out harmful UV rays.

Interestingly, the study did not show that melanomas occurred any more frequently within tattooed skin than in un-tattooed areas. This suggests that tattoo ink itself is unlikely to be directly carcinogenic, though some research suggests that it might be.

However, the researchers urge caution. This is one of the first major studies on tattoos and melanoma, so the results suggest new ideas to test rather than prove that tattoos are protective.

Comparisons with previous research, conducted in other countries, also reveal inconsistent findings. Some studies have shown skin cancers – including melanoma – in tattooed populations or areas of the body. However, these studies have also been hampered by small sample sizes, lack of information on other key risk factors, and diverse sun-bathing habits around the world.

What does this all mean in practical terms? The findings are far from a green light to seek out tattoos as a shield against melanoma. Crucially, the absence of detailed behavioural and biological data means that the observed effects could just as easily reflect differences in lifestyle or unrecorded habits in tattooed populations.

For now, the fundamental advice for melanoma prevention is unchanged: limit sun exposure, wear sunscreen, and check your skin regularly, regardless of ink status.

For those who already have multiple tattoos, the study does, however, provide some reassuring news: there is currently no evidence that tattooing increases the risk of melanoma, and any association with reduced risk may simply reflect other factors.

The broader message, though, is one of scientific caution. Interesting signals like these warrant further investigation in larger, more carefully controlled studies, that can fully account for all the complexities of cancer risk and human behaviour. Until then, tattoos may remain a personal choice, but definitely not a medically endorsed strategy for staving off skin cancer.

This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Justin Stebbing, Anglia Ruskin University

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Justin Stebbing does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.