Do tattoos shield your skin from the sun or worsen its effects? A recent study I conducted with colleagues raises some concerns.
We discovered that individuals with tattoos had a 29% higher risk of developing melanoma, a severe skin cancer often linked to UV exposure.
In contrast, tattoos didn’t seem to raise the risk of squamous cell carcinoma, another UV-related skin cancer. Though both cancers stem from similar causes, they originate in different cell types, with melanoma being significantly more dangerous.
Mainstream Expression with Uncertain Health Impacts
Tattoos serve as a strong means of self-expression and a key part of contemporary identity. In Sweden, roughly one in three adults has a tattoo, highlighting how body art has become widely mainstream.
Despite their widespread popularity, scientists still don’t know whether tattoos affect health or how any potential effects might develop over time.
Epidemiologists are working to answer these questions, but the research is challenging. People who get tattoos often differ from those who don’t in ways that can influence health outcomes.
Another obstacle is that most medical records don’t indicate whether someone has tattoos, making long-term patterns hard to track. Without this key information, it’s difficult to determine if tattoos themselves impact health or if observed differences are due to other factors.
Both melanoma and squamous cell carcinoma develop slowly and are relatively rare, making long-term studies difficult. Tracking large groups of tattooed and non-tattooed individuals over many years would be costly and time-consuming.
Case-Control Study of Tattoos and Cancer
To address this, our team took a different approach. We focused on people already diagnosed with cancer and looked back to determine who had tattoos. This method, called a case-control study, offers an efficient way to identify potential links.
Sweden has high-quality national registers that track health and demographic data. Using the National Cancer Register, we identified everyone aged 20 to 60 diagnosed with melanoma in 2017 or squamous cell carcinoma between 2014 and 2017.
This included 2,880 melanoma cases and 2,821 squamous cell carcinoma cases. For each case, we selected three age- and sex-matched controls from the Total Population Register who had no history of skin cancer.
We then sent questionnaires to all participants asking about tattoos—including decorative tattoos, permanent makeup, and medical tattoos—as well as their size, location, and age at first tattoo. This helped us determine whether tattoos were acquired before or after cancer diagnosis.
Ultimately, 5,695 people participated in the melanoma study (1,598 with melanoma) and 6,151 in the squamous cell carcinoma study (1,600 with that cancer).
Tattoo-Related Risks for Melanoma and Squamous Cell Carcinoma
Individuals with tattoos had a 29% higher likelihood of developing melanoma compared to those without tattoos. The risk appeared greatest among people who had tattoos for over ten years, but the smaller sample size in this group means the findings should be interpreted with caution.
For squamous cell carcinoma, tattoos had no impact. The findings were consistent across analyses, indicating no link between tattoos and this type of skin cancer.
We also found no evidence that larger tattoos increased risk, which was surprising given that bigger tattoos contain more ink and potentially harmful substances.
One possible reason is that tattoo ink doesn’t stay confined to the skin. The immune system treats it as foreign and transports some particles to the lymph nodes, where they can remain long-term. While it’s unclear if this causes harm, it could trigger chronic inflammation, which has been associated with cancer development.
Another possibility is measurement error, as people often overestimate tattoo size. Future studies using more precise methods may help clarify this.
Influence of Lifestyle and other Confounding Factors
What sets this study apart is the breadth of lifestyle factors we were able to examine. We considered sun exposure (both at work and during leisure), tanning bed use, smoking, education, marital status, and household income, along with skin type, pigmentation, age, and sex.
These details are important because they can affect both the likelihood of getting tattoos and developing cancer. For example, people who spend more time in the sun may be more prone to both tattoos and melanoma. Adjusting for these differences helps reduce bias and increases confidence in the results.
In research, this is called confounding. If confounding factors aren’t properly controlled, they can skew findings and produce misleading conclusions.
A recent US study suggested that large tattoos might lower melanoma risk, but it didn’t account for key factors like skin type or UV exposure.
The findings may reflect behavior rather than biology. For instance, individuals with large tattoos might avoid sunbathing or tanning beds to protect their tattoos, which could naturally limit UV exposure.
Do tattoos cause skin cancer? The short answer is that we don’t know yet. Our study suggests a potential link between tattoos and melanoma, but a single study cannot prove causation.
Understanding Risks and Staying Vigilant with Tattoos
Further research is needed to explore possible biological mechanisms, such as chronic inflammation, and to investigate how different inks or colors interact with UV exposure. Tattoo pigments vary widely, and many can break down into harmful by-products when exposed to sunlight or laser removal treatments.
If you have tattoos, there’s no need to panic, but staying vigilant is important. Protect your skin from UV radiation as usual: use sunscreen, avoid excessive tanning, and regularly check for new or changing moles.
Our findings underscore the need for long-term monitoring and improved recording of tattoo data in health records. With tattoos now common globally, this represents a significant public health concern. Ongoing research into the biology and long-term effects of tattoos will help people make informed decisions about their bodies, their art, and their health.
Read the original article on: Sciencealert
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