Melanoma less common in people with several tattoos

Researchers at the Huntsman Cancer Institute at the University of Utah report that individuals with multiple tattoos appear to have a lower risk of melanoma, a finding that challenges long-standing assumptions about tattoo inks and cancer risk. The study, published in the Journal of the National Cancer Institute, analyzed more than 7,000 Utah residents and found that while a single tattoo session was linked with an increased incidence of melanoma, those with multiple tattoo sessions showed progressively lower risk.

“Our findings suggest more tattoo exposure is associated with reduced melanoma risk, which does not support previously hypothesized associations between tattooing and increased melanoma risk,” the authors wrote.

The research team, led by Jennifer Doherty, PhD, MS, professor of population health sciences, documented a divergence based on tattoo exposure: people with only one tattoo session were more likely to develop melanoma—particularly melanoma in situ—whereas those with two or more tattoo sessions had decreasing rates of both in situ and invasive disease.

“Tattoos are increasingly common, and it’s an understudied form of environmental exposure, especially in young people,” Dr. Doherty said in a news release. “We really need to understand how tattoos could impact risk for different types of cancer. For melanoma, the results seem to be mixed. But we see people with two, three, and four tattoo sessions having decreasing risk, and that’s a stronger pattern than the increased risk with just one session.”

The biologic mechanisms remain speculative, they report. Tattoo inks contain carcinogens, including metals and chemicals, that can degrade over time and trigger inflammation, a process typically associated with increased cancer risk. Yet the Utah data show the opposite association at higher exposure levels.

Rachel McCarty, PhD, first author and post-doctoral scientist at the International Agency for Research on Cancer, cautioned against overinterpreting the apparent protection. “The results that tattoos could decrease melanoma risk surprised us. But this isn’t a black and white case of ‘get more tattoos, and you could lower your risk of melanoma,’” she said. “Instead, we need to do more research to understand … if this decreased risk is simply due to behavioural or physical factors, or if there could be beneficial immune responses associated with tattooing which lower melanoma risk.”

The authors suggested potential explanations: individuals with tattoos may be more vigilant with sun protection, tattoos might serve as a limited physical barrier to ultraviolet radiation, or tattooing could induce immune responses against atypical cells.

The case-control study included 1,167 melanoma cases and 5,835 matched controls. Those with four or more tattoo sessions had a 56% lower risk of melanoma (OR 0.44; 95% CI 0.27–0.67) compared with never-tattooed individuals, while those with three or more large tattoos had a 74% lower risk.

Despite the unexpected findings, investigators warned that tattooing has been linked in prior studies to blood cancers, and the protective association may not extend to other malignancies.

“The Mountain West and the area we serve have some of the highest melanoma rates in the country,” said Douglas Grossman, MD, PhD, co-director of the Melanoma Center at the institute. “Better understanding risk factors for melanoma will help us improve prevention strategies across the region, advise our patients about risks more accurately, and ultimately save lives.”