Scientists have found a strange link between tattoos and melanoma

People who have had tattoos in multiple sessions have a lower incidence of melanoma, researchers at the Huntsman Cancer Institute at the University of Utah have concluded. However, the authors emphasise a key caveat: the results do not mean that tattoos "protect" against skin cancer, and the mechanism of the link is not yet clear.

What the study showed

The team, led by epidemiologist Jennifer Doherty, analysed data from Utah residents and found that people with two or more tattoo sessions had a lower risk of invasive melanoma and melanoma in situ (where tumour cells remain in the upper layers of the skin and are usually easier to remove).

A paradox was found: in contrast, participants who had only one tattoo session were more likely to fall into the group with melanoma - especially in situ melanoma. The researchers call the reasons for this difference speculative and insist more work is needed.

"Heavy exposure" and specific numbers

The parsing of the results notes that "heavier" tattooing is associated with a reduced likelihood of diagnosis. For example, for people with 4+ tattoo sessions, an OR estimate of 0.44 is given (i.e. lower odds of melanoma compared to the untattooed). For in situ melanoma in those who had 1 session, the opposite pattern is described, with an OR of 1.85, whereas with 4+ sessions, again a decrease (also OR 0.44).

The authors discuss several possible explanations: people with multiple sessions may be more strict about sun protection, and the tattooing procedure itself is theoretically capable of triggering immune responses. But these are still hypotheses - the study is observational and does not prove causation.

Why the scientists were surprised by the result

The team originally hypothesised the opposite: that tattoos could increase risks due to potentially carcinogenic ink components (e.g. metals and other chemical compounds), possible pigment breakdown products over time and inflammatory reactions in the skin. Nevertheless, a mixed picture emerged, requiring rechecking with other samples.

Important warning about "not to be confused with protection"

The researchers separately remind us: even though statistically the risk of melanoma in this work is lower in people with multiple sessions, this does not guarantee similar effects for other cancers. The press materials mention that other projects have linked tattooing to increased risks of some hematopoietic/haematological tumours, so it's not possible to interpret the results as "tattoos are beneficial".

Context

Tattoos are a mass phenomenon in the US: according to the Pew Research Center, about 32% of adults have tattoos, and about 41% of people under 30 have tattoos.