My uneducated guess is that this is mostly an effect of other risky behavior (more prevalent among tattooed people) that they’ve not accounted for, such as alcohol consumption.
Possible association between tattoos and lymphoma revealed
“After taking into account other relevant factors, such as smoking and age, we found that the risk of developing lymphoma was 21 percent higher among those who were tattooed. 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”, says Christel Nielsen.
