Our study included everyone in Sweden who had been diagnosed with lymphoma at the age of 20 to 60 years between 2007 and 2017. For each person with lymphoma, three random people of the same sex and age but without lymphoma were identified (the “controls” used for comparison).
The size of the tattoos did not seem to matter. What did matter was time - how long participants had had their tattoos. The risk seemed to be higher for new tattoos (received within two years) and for older tattoos (received more than ten years ago).
There is clearly a need to delve deeper to understand the health implications of tattoos. Right now, my colleagues and I are completing parallel studies on two types of skin cancer and are about to start new research to find out if there is an increased risk of immune-system-related conditions, such as thyroid disease and sarcoidosis.
Very odd how the size of the tattoo appears to not matter, and that the risk appears to dip for several years after receiving the tattoo. This would seem to suggest the existence of other factors for which the data has not been properly adjusted - or just an unintuitively complex mechanism.
