Tattoos linked to higher risk of malignant lymphoma, study finds

By Pooja Toshniwal PahariaReviewed by Susha Cheriyedath, M.Sc.May 28 2024

In a recent study published in the journal eClinicalMedicine, researchers determined the relationship between tattoo ink exposure and malignant lymphoma and lymphoma subtype risk.

Study: Tattoos as a risk factor for malignant lymphoma: a population-based case–control study. Image Credit: Charcompix / Shutterstock

Background

Tattoos have recently gained popularity, although their long-term health repercussions are unknown. Tattoo ink includes carcinogenic substances such as polycyclic aromatic hydrocarbons (PAH), primary aromatic amines (PAA), and metals. Tattoo inks elicit an immune reaction, resulting in the migration of tattoo inks from injection sites. Although the presence of tattoo pigments within lymph nodes is proven, their long-term consequences on health are unknown.

The global growth in malignant lymphoma incidence is unexplained, and it is critical to discover any link to lifestyle variables. Lymph nodes contain growing cells and are vulnerable to carcinogenic substances. Studies associate exposure to solvents, flame retardants, pesticides, and hair dyes with immunologic disturbance, which plays a role in malignant lymphoma development.

About the study

In the present population-level study, researchers investigated tattoos as a risk factor for lymphoma. They also evaluated exposure-response connections and the effect of exposure length, considering the interval between the first tattoo and the index year (year of lymphoma diagnosis).

The researchers analyzed Swedish National Authority Registers to identify incidents of malignant lymphoma cases diagnosed using the International Classification of Diseases for Oncology, third edition codes, from 2007 to 2017 among individuals between 20 and 60 years old. They used incidence density sampling on Total Population Register data to choose three randomly selected sex- and age-matched controls for each case.

The team analyzed exposure using questionnaires sent by the Swedish government in 2021, with data on probable confounding variables obtained from registries. Respondents provided their age at first tattoo, in addition to tattoo features such as color, total area of inked body surface, tattooer skill level, and geographical region of tattooing. The researchers used multivariate logistic regressions to calculate the incidence rate ratios (IRR) for malignant lymphoma among tattooed individuals. Study covariates included educational attainment, family income, smoking, and marital status.

The researchers conducted subgroup analyses to investigate the relationship between tattoo exposure and lymphoma subtypes. They conducted sensitivity analyses to assess the influence of confounding from hazardous occupations or immunosuppressive medication use. They utilized the International Agency for Research on Cancer (IARC) classification to determine whether chemical exposures had sufficient or limited evidence for lymphoma. They examined possible survivorship bias by incorporating replies from deceased patients' next-of-kin in the study. To assess possible reverse causality, they eliminated those receiving their first tattoo within a year of a cancer diagnosis.

Results and discussion

The sample population included 11,905 people, with a response rate of 54% for cases (n = 1,398) and 47% for controls (n = 4,193). Tattoo prevalence rates were 21% and 18% in the case and control groups, respectively. Individuals with tattoos showed a higher risk of lymphoma development (IRR, 1.2). Individuals reporting less than a two-year gap between their initial tattoo ink exposure and the lymphoma diagnosis year were most likely to develop lymphoma (IRR, 1.8). The risk was reduced with intermediate tattoo ink exposure length (between 3.0 and 10 years) but was elevated among those acquiring their initial tattoos at least 11 years before their index years (IRR, 1.2).

The researchers found no indication of an increased risk with more total body surface tattooed. Tattoo exposure was related to the highest risk of developing diffuse-type large B-cell lymphomas (IRR, 1.3) and follicular lymphomas (IRR, 1.3). Sensitivity studies produced similar results, indicating the robustness of the primary findings.

Laser therapy for tattoo removal seems to increase malignancy incidence significantly. The relative risk of lymphoma among tattooed patients who had received laser therapy was 2.6 in the matched study. The unpaired analysis revealed that tattoo laser removal had a significant modification effect (IRR, 3.0). The findings may be due to the cleavage of azo-type compounds in tattoo inks into carcinogenic amines such as o-toluidine, 3,3′ -dichlorobenzene, and 2- amino-4-nitrotoluene toxic compounds after laser irradiation.

The study found that tattooed individuals have a 21% higher chance of developing lymphoma than non-tattooed individuals. Tattoos obtained 0–2 years or ≥11 years before the index year may enhance the risk of lymphoma. Tattoo ink exposure may be associated with tumor initiation and progression, with the latter having significantly rapid consequences. Tattoo ink's toxicokinetics suggest a time-dependent impact. The researchers noted the highest risk in cases where the first tattoos were less than two years before the index year, potentially due to reverse causation. Laser therapy for tattoo removal resulted in a much greater risk estimate. The long-term health repercussions of tattoo exposure and the implications of laser tattoo removal warrant additional research concerning potential public health implications. The findings indicated that tattooed individuals may develop B-cell lymphomas, particularly the diffuse large B-cell and follicular subtypes.

Concerning the mechanism underlying the association between tattoo ink exposure and malignant lymphoma, the researchers state, "We do not yet know why this was the case. One can only speculate that a tattoo, regardless of size, triggers a low-grade inflammation in the body, which in turn can trigger cancer. The picture is thus more complex than we initially thought."  

Video - Possible association between tattoos and lymphoma revealed