> A hypothesis that Christel Nielsen's research group had before the study was that the size of the tattoo would affect the lymphoma risk. They thought that a full body tattoo might be associated with a greater risk of cancer compared to a small butterfly on the shoulder, for example. Unexpectedly, the area of tattooed body surface turned out not to matter.
As someone pointed out on the other thread about this[1], the lack of dose response makes it very difficult to see this as a direct correlation and not reflective of other confounding factors.