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Tattoos and cancer — new study in twins may show link

A recently published large study from Denmark seems to show a link between tattoos and cancer. It has not established a causal link, but getting tattoos may be riskier than we have been led to believe.

Tattoos have become increasingly popular in the USA and other countries. According to a 2023 Pew survey, one-third of Americans have at least one tattoo, while 22% have more than one. If tattoos do have a long-term risk of cancer, research must be done to determine whether that risk exists.

This post will review the new study and ascertain whether it provides us with a warning about the risk of tattoos and cancer.

photo of person wearing ripped jeans tattoos cancer

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Tattoos and cancer research

In a paper published on 15 January 2025 in BMC Public Health, Signe Bedsted Clemmensen, PhD, Department of Epidemiology, Biostatistics, and Biodemography, Institute of Public Health, University of Southern Denmark (SDU), Odense, Denmark, and colleagues, analyzed data from the Danish Twin Tattoo Cohort (DTTC).

The DTTC was created in 2021 by SDU scientists to survey twin pairs about their tattoo history, with volunteers solicited from SDU’s Danish Twin Registry. This allowed the researchers to know a person’s tattoo status and to track whether they later developed cancer. They specifically looked for cancer cases in parts of the body where tattoo ink particles are known to deposit, such as the skin and lymph nodes.

The researchers developed a cohort study of 2,367 randomly selected twins and a case-control study of 316 twins born between 1960 and 1996. Both studies compared the cancer-related outcomes of tattooed and non-tattooed twins.

Here are the key results:

The risk of skin cancer (of any type except basal cell carcinoma) was 1.62 times higher among tattooed individuals compared to non-tattooed.

The risk of skin cancer in individuals with tattoos larger than the palm of a hand was 2.37 times higher.

The risk of lymphoma in individuals with tattoos larger than the palm of a hand was 2.73 times higher.

In the cohort study, the risk for skin cancer was 3.91 times higher for skin cancer and 2.83 times higher for basal cell carcinoma.

grayscale photo of tattoo neon signage

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Summary

The most important point I can make about this type of study is that it cannot show causality. Even though the use of twins reduces genetic bias in the results, there could be some other factors that cause the increase in cancer in the tattooed group.

For example, people who get tattoos may be more likely to engage in other behaviors that increase the risk of cancer like smoking or alcohol use. Also, tattoos might lessen the chances of someone noticing the initial signs of skin cancer, which would lead to worse outcomes.

However, another study (which I reviewed) showed an increased risk of lymphoma in individuals who had tattoos. This study also could not show causality.

One of the critical steps in determining causality is to show a biologically plausible mechanism where the tattoos lead to cancer. We don’t know what might cause the increase in risk, but it could be the ink or the needle injecting the ink. That’s where research needs to go.

At this time, we have a strong correlation — the increase in cancer risk is clinically significant. This study was well-designed, so it was powered to show a significant increase in cancer risk in tattooed and non-tattooed individuals.

There probably will be more research in this area since the early evidence is so strong. The results will bear watching.

Citations

Michael Simpson

Lifetime lover of science, especially biomedical research. Spent years in academics, business development, research, and traveling the world shilling for Big Pharma. I love sports, mostly college basketball and football, hockey, and baseball. I enjoy great food and intelligent conversation. And a delicious morning coffee!