Do Tattoos Increase Lymphoma Risk?

eClinicalMedicine published an article on May 21, 2024, suggesting that tattoos may be a risk factor for lymphoma.

Because tattoos are applied to skin, research has generally focused on skin cancer. The main increase in risk, however, may be in the lymph nodes. 

Lymphoma and Known Risk Factors

Lymphoma is cancer of the lymphatic system, usually beginning in lymphatic tissues such as lymph nodes, the spleen, thymus and bone marrow. Known risk factors include immune system disorders, certain infections (such as Epstein-Barr virus), exposure to some chemicals and a family history of lymphoma. Lymphoma incidence has increased globally in recent years, making it important to understand the reasons.

Tattoos and Lymphoma Risk

Tattoos have become dramatically more popular over recent decades. Several European studies now report prevalence above 20%, while US prevalence is estimated at approximately 30%. Most people get their first tattoo at a young age, exposing them to the chemical components of tattoo ink for almost their entire lives. Research into long-term health effects, however, has only recently begun.

Tattoo Ink Chemistry and Effects on the Body

Tattoo inks are mixtures of organic and inorganic color pigments, additives, and precursors and byproducts of pigment synthesis. Colored inks contain primary aromatic amines (PAA), while black inks often contain polycyclic aromatic hydrocarbons (PAH). Inks of every color may contain metals such as arsenic, chromium, cobalt, lead and nickel. The International Agency for Research on Cancer has classified a substantial proportion of these chemicals as carcinogenic .

Tattooing injects ink into the dermis by repeatedly puncturing the skin barrier. Any antigen crossing that barrier triggers a local immune response and is transported to lymph nodes. Tattoo pigment commonly travels to lymph nodes: an estimated 32% of injected pigment has translocated after 6 weeks, potentially reaching 99% over time.

Pigmented, enlarged lymph nodes in tattooed people have been described clinically for decades. Transport of black and colored tattoo pigments into human lymph nodes and accumulation of metal particles from needle wear have been confirmed. Lymph nodes contain rapidly proliferating immune cells and are susceptible targets for carcinogenic chemicals. Growing evidence suggests that immune disruption from exposure to solvents, flame retardants, pesticides and hair dyes plays a key role in lymphoma development.

The Recent Swedish Study

Using Swedish national health data, researchers conducted a population-based case-control study to investigate whether tattoo exposure increases lymphoma risk. They examined exposure-response relationships and exposure duration, considering the interval between the first tattoo and the index year. They also investigated associations with lymphoma subtypes.

Principal investigator Dr. Christel Nielsen explained that the body recognizes tattoo ink injected into skin as foreign material, activating the immune system. A large proportion moves from skin to lymph nodes and accumulates there.

Study Details and Results

The study identified 2,938 patients diagnosed with lymphoma between 2007 and 2017. Of these, 1,398 responded to the questionnaire. In the control group, 4,193 people participated.

Patients with lymphoma were identified through population registers and matched with controls of the same age and sex who did not have lymphoma. Participants completed a lifestyle questionnaire indicating whether they had tattoos.

• Tattoos were reported by 21% of patients with lymphoma and 18% of controls.
• After accounting for other relevant factors, such as smoking and age, lymphoma risk was 21% higher in tattooed individuals (confidence interval 0.99-1.48).
• Researchers initially thought tattoo size might affect lymphoma risk—for example, that a full-body tattoo might carry greater risk than a small tattoo. However, no association was found between tattooed body surface area and lymphoma risk.

The researchers do not yet know why. They can only speculate that tattoos, regardless of size, may trigger low-grade inflammation that could, in turn, trigger cancer. They said the situation was more complex than initially expected.

Commentary

It is important to remember that lymphoma is rare and these findings apply at group level. They need further investigation in other studies, and such research is ongoing.

The relationship between tattoos and cancer remains debated. A literature review more than a decade ago compared the number of tattoo-associated skin cancer cases with the worldwide tattooed population and suggested that the association might be coincidental. Case reports help identify research questions and generate hypotheses, but selective reporting and the lack of comparison groups prevent them from establishing causality. Without well-designed epidemiological research, there is no scientific basis for robustly assessing a possible link between tattoo exposure and cancer.

This case-control study's 21% increase is based on an incidence rate ratio (IRR). It indicates an association, not a direct cause-and-effect relationship. Because the confidence interval (0.99-1.48) includes 1, the results are not statistically significant. They are therefore inconclusive and require further research.

To our knowledge, the only published epidemiological study of tattoo exposure and lymphoma was by Warner and colleagues. It lacked sufficient power because few participants had tattoos. The present study is therefore the first to provide insights into the possible association using a large, population-based design. A single epidemiological study cannot establish causality, however, and more research is needed.

Carcinogenesis is a multistage process of cellular transformation, broadly described as initiation, promotion and progression. External chemical carcinogens may act at one or more stages, often interacting with other agents in complex ways. Because tattoo inks are heterogeneous chemical mixtures, an analytical strategy for exposure latency could not be established in this study. Instead, researchers examined exposure duration using the interval between the first tattoo and the index year. Tattoos obtained 0-2 years before the index year and those obtained 11 or more years earlier both appeared potentially associated with increased lymphoma risk. If confirmed, these findings could suggest that tattoo ink exposure is involved in both tumor initiation and promotion.

The researchers called for more work on tattoos' long-term health effects and plan to assess possible associations with other cancers and inflammatory diseases.

In conclusion, when stating that lymphoma risk was 21% higher among tattooed people, we must emphasize that this is an association, not evidence of causality. The study is hypothesis-generating. Because tattoo inks contain carcinogens, stronger future studies may clarify this possible relationship. 

People will probably continue expressing their identity through tattoos, making tattoo safety important for society. Individuals should know that tattoos may affect health and consult a doctor about symptoms they think could be tattoo-related.