Tattoos are much more common than they were a couple of decades ago. According to the Pew Research Center, 32% of US adults have one, and 22% have more than one. Now considered to be more socially acceptable, everyone – from pop stars to politicians – seems to be sporting ink.
Coupled with the global rise in the popularity of tattoos has been a largely unexplained increase in the incidence of malignant lymphoma, a cancer of the lymphatic system. In a new study, researchers from Lund University in Sweden examined the two to see if there was a connection.
“We have identified people diagnosed with lymphoma via population registers,” said Christel Nielsen, associate professor of epidemiology at Lund University and the study’s lead and corresponding author. “These individuals were then matched with a control group of the same sex and age, but without lymphoma. The study participants answered a questionnaire about lifestyle factors to determine whether they were tattooed or not.”
The lymphatic system is part of the immune system. It keeps body fluid levels in balance and defends against infection. There are two main types of cancer affecting the lymphatic system: non-Hodgkin lymphoma (NHL), which accounts for around 90% of all lymphomas, and Hodgkin lymphoma. There are about 40 subtypes of NHL, which differ in how fast they grow and spread. NHL is one of the most common cancers in the US and can occur at any age.
The study included 11,905 Swedish people, 2,938 of whom had lymphoma between 20 and 60 years of age (‘cases’). Of those participants, 54% answered the questionnaire about tattoos; 47% of the controls (those without lymphoma) did the same. Tattoo prevalence was 21% among cases and 18% among controls.
“After taking into account other relevant factors, such as smoking and age, we found that the risk of developing lymphoma was 21% higher among those who were tattooed,” Nielsen said. “The results now need to be verified and investigated further in other studies and such research is ongoing.”
Before analyzing the data, the researchers hypothesized that a larger tattoo might’ve meant an increased risk of lymphoma. This was not the case: the risk remained regardless of size.
“We do not yet know why this was the case,” said Nielsen. “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.”
Previous studies have found particles of tattoo ink – and, indeed, metal nanoparticles from the tattoo needle itself – can travel to the lymph nodes.
“We already know that when the tattoo ink is injected into the skin, the body interprets this as something foreign that should not be there and the immune system is activated,” Nielsen said. “A large part of the ink is transported away from the skin to the lymph nodes, where it is deposited.”
The researchers will now examine whether there is a link between tattoos and other types of cancer, as well as inflammatory diseases. They offer the following advice.
“People will likely want to continue to express their identify through tattoos, and therefore it is very important that we as a society can make sure that it is safe,” said Nielsen. “For the individual, it is good to know that tattoos can affect your health, and that you should turn to your health care provider if you experience symptoms that you believe could be related to your tattoo.”
The study was published in the journal eClinical Medicine.
Source: Lund University
Whenever a university publishes research, you can be sure they controlled for confounding factors. If they didn't, they can't get published in a peer-reviewed journal.
People are far likelier to comment "Correlation is not causation!" when they don't welcome a study's results.