Tattoos may increase cancer risk - twin study findings

A large Danish study conducted by scientists at the University of Southern Denmark (SDU) and the University of Helsinki has found that large tattoo holders are more likely to be diagnosed with lymphoma and skin cancer.

Key facts of the study

1. Study Subject
   The scientists analysed data from more than 5,900 people from the Danish Twin Tattoo Cohort (Danish Twin Tattoo Cohort). This unique sample allowed the comparison of genetically similar people - twins - to identify the influence of purely external factors related to tattoos.

2. The main finding
   Tattoo wearers were observed to have an increased incidence of lymphoma and skin tumours compared to those without tattoos. The association was particularly pronounced in people with large tattoos, which were larger than the palm of the hand. For lymphomas, the incidence of the disease was almost three times higher in those with "large tattoos" relative to those without tattoos.

3. The role of the lymphatic system
   The researchers emphasise that the pigment particles accumulate in the lymph nodes, which form an important part of the immune system. A possible hypothesis: the body tries to "fight" foreign substances, which can maintain chronic inflammation for years and increase the likelihood of cancer.

Why these results are important

• The rise in popularity of tattoos
  Scientists estimate that by the age of 25, approximately 40% of women and 30% of men have at least one tattoo, and many order large "projects" at once.
• A question of colour
  Previous studies indicate that the composition of ink may contain potentially harmful components. Red ink, for example, is more likely to cause allergic reactions. No clear correlation with a specific pigment was found in this study, but this does not rule out a role for colour in cancer risks.

Future research directions

The scientists plan to look further into how exactly pigment - in particular microparticles - interacts with lymph nodes on a molecular level and how this increases the risk of certain types of lymphoma. Another question is whether there is a time-dependent effect, since many people get tattoos at a young age and keep them for decades.

According to assistant professor Signe Bedsted Clemmensen, a better understanding of the biological mechanisms will help formulate recommendations and possibly reduce the risks - for example, through improved ink formulations or special medical restrictions on large tattoos.

While it's too early to call tattoos a major source of cancer, the findings urge caution. If you're going to get a large tattoo, it's worth considering the possible long-term effects on your immune system and choosing your pigment more carefully. The scientific community continues to study the topic to determine how serious the threat is and how it can be minimised.

Study reference:
Clemmensen, S. B. et al. Tattoo ink exposure is associated with lymphoma and skin cancers - a Danish study of twins, BMC Public Health (2025).DOI: 10.1186/s12889-025-21413-3