Longevity Briefs: Do Tattoos Increase Cancer Risk?

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The problem:

Tattoos have become increasingly accepted and popular over the past few decades, thanks in no small part to social media. For most people, the decision of whether or not to get a tattoo is about willingness to make a mostly permanent modification to one’s body. Yet the health implications of getting a tattoo are largely unexplored. Tattoo inks often contain carcinogenic chemicals that can make their way to the lymph nodes, where white blood cells gather and survey the lymphatic fluid for signs of infection. In this study, researchers set out to investigate whether those chemicals might promote lymphoma, a type of cancer that grows from lymphocytes (a class of white blood cell that includes T and B cells).

The discovery:

Analysing data from the Swedish National Cancer Register, researchers identified 1,398 people with lymphoma and 4,193 people without lymphoma as controls. Participants were questioned about whether they had been tattooed, as well as specifics such as when they received them, how many, how large and so on. The researchers found that, after controlling for confounding factors, people with tattoos were about 21% more likely to have been diagnosed with malignant lymphoma than matched controls of the same age and sex.

The risk was highest within a few years of receiving a tattoo. People who had received a tattoo within the previous 2 years were 81% more likely to be diagnosed with malignant lymphoma than untattooed controls. This increased risk disappeared after 3 years but later re-emerged, leaving people with tattoos with a 19% increased risk after 11 years. Interestingly, the size of the tattoo had no significant impact on risk. More intriguing still was that getting a tattoo removed by laser treatment appeared to drastically increase the risk of lymphoma. Overall, people who had tattoos removed by laser were over two and a half times as likely to be diagnosed with malignant lymphoma compared to matched untattooed controls. This estimate had a large confidence interval due to the small number of people who had received laser treatment (in other words, the real risk could be a lot higher or a lot lower than this).

The implications:

The findings suggest that tattoo exposure is associated with an increased risk of malignant lymphoma of about 21%. While this sounds alarming, it’s important to be aware that 21% of a small number remains a small number. About 1 in 5000 people in the United States will be diagnosed with non-Hodgkin lymphoma, the most common type by far, so getting lymphoma because you have tattoos is by no means likely. The link between laser treatment and lymphoma is interesting. Laser treatment breaks down the ink within the skin into smaller particles that are then removed by the immune system, and may therefore expose lymphocytes to higher levels of carcinogens.

This study was observational in nature, so it’s impossible to know for sure that all of the increased risk was due to tattoo exposure and not some other factor, such as people who get tattoos being more likely to smoke, for example. While the researchers did attempt to make adjustments for things like smoking and wealth, not everything can be controlled for perfectly. It also relies on self-reporting, which is prone to reporting bias. This topic certainly deserves further research, as so far there appears to be only one other study concerning tattoo exposure and lymphoma. That study found no significant association between tattoo exposure and lymphoma risk, but was much smaller than the present study.