Tattoos may be a risk factor for malignant lymphoma, according to a case-control study from the Swedish National Cancer Register.
It proposed that the potential link may be related to immune disruption caused by tattoo-related chemicals deposited within the lymphatic system.
The study, published in eClinicalMedicine [link here], comprised all incident cases of malignant lymphoma diagnosed between 2007 and 2017 in Swedish adults 20–60 years of age matched 1:3 with controls.
A questionnaire sent in 2021 to the 11,905 individuals in the cohort assessed the presence or absence of any tattoos, including decorative, cosmetic, medical and removed tattoos.
From the respondents, tattoo prevalence was 21% among lymphoma cases and 18% among controls (adjusted incidence rate ratios 1.21).
The most common lymphoma subtypes were DLBCL (28%), Hodgkin lymphoma (21%) and follicular lymphoma (18%).
“The risk associated with tattoo exposure was strongest for diffuse large B-cell lymphoma (IRR 1.30; 95% CI 0.99–1.71), followed by follicular lymphoma (IRR 1.29; 95% CI 0.92–1.82),” the study said.
Tattooed cases and controls had received their first tattoo – mostly decorative tattoos (>90%) – at about the same age (median ages 23 and 22 years) and mostly by a professional tattoo artist (>85%).
The study found 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 (i.e., three to ten years), but seemed to increase again in individuals who received their first tattoo ≥11 years before the index year (IRR = 1.19; 95% CI 0.94–1.50),” it said.
“If these findings can be corroborated by further studies, they would indicate that exposure to tattoo ink may be associated with both tumour initiation, which is often associated with a latency of several years, and tumour promotion where effects occur much faster.”
In a sub group analysis accounting for exposure duration, the risk for DLBCL seemed to be highest in participants with ≥11 years from their first tattoo, whereas the risk for follicular lymphoma seemed to be elevated both in individuals within 0–2 years from their first tattoo and with ≥11 years from the first tattoo.
Variables such as the total area of tattooed body surface, colour scheme of the tattoo and number of tattoo sessions were similar in both cases and controls.
Cases were slightly more likely than controls to have been tattooed outside Sweden (18% v 12%) and undergone laser removal of their tattoo (5% v 2%).
The investigators said that translocation and deposition of tattoo pigment in lymph nodes has been previously confirmed but the long-term health effects were unknown.
However, tattoo inks are “cocktails of organic and inorganic colour pigments, together with precursors and byproducts from the pigment synthesis, and additives.”
“Coloured inks may contain primary aromatic amines (PAA), black inks often contain polycyclic aromatic hydrocarbons (PAH), and metals (i.e., arsenic, chromium, cobalt, lead, and nickel) are found in ink of all colours,” they said.
“A significant and concerning number of chemicals in tattoo ink are classified as carcinogenic by the International Agency for Research on Cancer.”
Interestingly, they found that despite low numbers, laser treatment for tattoo removal resulted in a substantially higher risk estimate for lymphoma (IRR = 2.99; 95% CI 1.37–6.52).
“These results align with evidence from experimental studies demonstrating cleavage of azo compounds in tattoo ink into carcinogenic aromatic amines like o-toluidine, 2-amino-4-nitrotoluene and 3,3′-dichlorobenzidine toxic compounds after laser irradiation,” they said.
“Clearly, not only the long-term health effects of tattoo exposure per se but also the implications of laser treatment for tattoo removal warrants further investigation in light of the potential public health implications.”