Swedish scientists have called for urgent in-depth research after their recent study, the first of its kind, suggested that tattoo ink might increase the risk of malignant lymphoma by 20% by triggering an immunologic response.
The lymphatic system is the body’s disease-fighting network, and includes the lymph nodes, spleen, thymus gland and bone marrow: the main types of lymphoma are Hodgkin’s and non-Hodgkin’s.
Medscape reports that Swedish scientists, led by Christel Nielsen of Lund University, said that when applied to the skin, tattoo ink, which often contains carcinogens, triggers an immunologic response.
They said that their findings underscore the importance of regulatory measures to control the chemical composition of tattoo ink.
The population-based case-control study included all incident cases of malignant lymphoma in adults aged 20-60 in the Swedish National Cancer Register between 2007 and 2017 (n = 11 905).
Tattoo exposure was assessed by a structured questionnaire in both cases and three random age- and sex-matched controls without lymphoma.
The primary outcome was the incidence rate ratio of malignant lymphoma in tattooed vs non-tattooed individuals.
The prevalence of tattoos was 21% among cases and 18% among controls, according to the team, according to the findings published in eClinical Medicine.
Lead correspondent Nielsen wrote that after adjustment for confounders, tattooed participants had a 21% higher risk for overall lymphoma than non-tattooed participants (incidence rate ratio = 1.21; 95% CI, 0.99-1.48).
In the subgroup analysis of lymphoma types, the highest risks of around 30% were found for diffuse large B-cell lymphoma (incidence rate ratio = 1.30; 95% CI, 0.99-1.71) and follicular lymphoma (incidence rate ratio = 1.29; 95% CI, 0.92-1.82) in tattooed vs non-tattooed individuals.
No evidence was found that the risk for lymphoma increased with a larger area of total tattooed body surface.
The authors reported that tattoo popularity has dramatically increased over the past few decades, with a current prevalence of ≥ 20% in European studies.
“Our findings suggested that tattoo exposure was associated with an increased risk for malignant lymphoma. More epidemiological research is urgently needed to establish causality.”
Limitations included the study’s observational case-control design, one of the weakest types of study designs for establishing causality, and its low response rate to the questionnaire of 47%-54%.
Study details
Tattoos as a risk factor for malignant lymphoma: a population-based case-control study
Christel Nielsen, Mats Jerkeman, Anna Saxne Jöud.
Published in The Lancet eClinical Medicine on 21 May 2024
Summary
Background
The popularity of tattoos has increased dramatically over the past few decades. Tattoo ink often contains carcinogenic chemicals, e.g., primary aromatic amines, polycyclic aromatic hydrocarbons, and metals. The tattooing process invokes an immunologic response that causes translocation of tattoo ink from the injection site. Deposition of tattoo pigment in lymph nodes has been confirmed but the long-term health effects remain unexplored. We used Swedish National Authority Registers with full population coverage to investigate the association between tattoo exposure and overall malignant lymphoma as well as lymphoma subtypes.
Methods
We performed a case-control study where we identified all incident cases of malignant lymphoma diagnosed between 2007 and 2017 in individuals aged 20-60 years in the Swedish National Cancer Register. Three random age- and sex-matched controls per case were sampled from the Total Population Register using incidence density sampling. We assessed exposure through a questionnaire in 2021, and data on potential confounders were retrieved from registers. We used multivariable logistic regression to estimate the incidence rate ratio (IRR) of malignant lymphoma in tattooed individuals.
Findings
The study population consisted of 11 905 individuals, and the response rate was 54% among cases (n = 1398) and 47% among controls (n = 4193). The tattoo prevalence was 21% among cases and 18% among controls. Tattooed individuals had a higher adjusted risk of overall lymphoma (IRR = 1.21; 95% CI 0.99–1.48). The risk of lymphoma was highest in individuals with less than two years between their first tattoo and the index year (IRR = 1.81; 95% CI 1.03–3.20). The risk decreased with intermediate exposure duration (three to 10 years) but increased again in individuals who received their first tattoo ≥11 years before the index year (IRR = 1.19; 95% CI 0.94–1.50). We found no evidence of increasing risk with a larger area of total tattooed body surface. The risk associated with tattoo exposure seemed to be highest for diffuse large B-cell lymphoma (IRR 1.30; 95% CI 0.99–1.71) and follicular lymphoma (IRR 1.29; 95% CI 0.92–1.82).
Interpretation
Our findings suggested that tattoo exposure was associated with an increased risk of malignant lymphoma. More epidemiologic research is urgently needed to establish causality.
Medscape article – Tattoos May Be Risk Factors for Malignant Lymphoma (Open access)
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