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SALT LAKE CITY — Tattoos may be a risk factor for cancer in the lymphatic system, according to a study by Swedish researchers that compared the incidence of lymphoma cases in people with a tattoo and among those who don't have one.
Others say the risk is being overblown and that the findings are not statistically significant.
Researchers from Lund University in Sweden used population registers there to identify people who had been diagnosed with lymphoma, matching them with a control group that was demographically the same but who didn't have any form of lymphoma. Then study participants answered a questionnaire about lifestyle factors, including whether they had at least one tattoo.
Findings were published in the journal eClinicalMedicine.
Tattoos are popular. The study cited prevalence rates above 20% in some European countries and about 30% in the United States. Pew Research Center reported last year that about a third of Americans have a tattoo, including 22% who have more than one. The researchers were surprised to discover that the size of the tattoo didn't matter in their study; a full-body tattoo did not increase risk compared to a little butterfly.
The authors suggest that any association might be due to the ink itself, which might be carcinogenic. Or perhaps tiny particles reach the lymph nodes and cause problems, they theorized. While the researchers emphasized the need for more study to determine if tattoos cause lymphoma, they wrote that "the study underscores the importance of regulatory measures to control the chemical composition of tattoo ink."
"People will likely want to continue to express their identity through tattoos, and therefore it is very important that we as a society can make sure that it is safe. 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," co-author Christel Nielsen, an associate professor in the Division of Occupational and Environmental Medicine at Lund University, stated in a news release.
Study methodology
Per the news release from Lund University, "In total, the entire study included 11,905 people. Of these, 2,938 people had lymphoma when they were between 20 and 60 years old. Of those, 1,398 people answered the questionnaire, while the number of participants in the control group was 4,193. In the group with lymphoma, 21% were tattooed (289 individuals), while 18% were tattooed in the control group without a lymphoma diagnosis (735 individuals)."
After controlling for factors like smoking and age, the researchers concluded the risk of developing lymphoma was 21% higher among those with tattoos. "It is important to remember that lymphoma is a rare disease and that our results apply at the group level. The results now need to be verified and investigated further in other studies and such research is ongoing," Nielsen said.
Malignant lymphoma is a cancer of the immune system. The Mayo Clinic reports that known risk factors include a weakened immune system, family history, specific infections like Epstein-Barr virus, Helicobacter pylori or HIV and age. Lymphoma is not preventable, the article said.
The most common types of cancer among those with tattoos were diffuse large B-cell non-Hodgkin lymphoma and follicular non-Hodgkin lymphoma, according to the study. Per the American Cancer Society, non-Hodgkin lymphoma is among the most common cancers in the U.S., making up 4% of all cancers. While it can affect people of all ages, most diagnoses are made at age 65 or older.
Overstated findings?
"Really overstated" is how Dr. Timothy Rebbeck, an epidemiologist at Dana-Farber Cancer Institute and professor at the Harvard T.H. Chan School of Public Health, described the findings to CNN. He was not involved with the research.
"If I were writing that paper, if I were the editor, I would have said the conclusion is, there is no evidence for a strong association," he said. He told CNN that "the data is solid," but lymphomas' primary risk factors are not something that comes with tattoos. He noted a study last year in the journal Cancer Research that concluded "there was no strong evidence that ever having received a tattoo versus never having received a tattoo was associated with overall risk of hematologic cancers, myeloid neoplasms or lymphomas."
Dr. Catherine Diefenbach, director of the Clinical Lymphoma Program at the NYU Langone Health Perlmutter Cancer Center, told CNN that people are becoming "nervous" about an early study that still has to be validated.
