One of the things that happens in medicine is that rare events are often not noted until a large enough population is involved in the medication or procedure.
When I was practicing pediatrics, it was my personal preference to not use a new medication until it had been out for over a year.
A good example of this was the medication Strattera. It was a non-stimulant ADHD medication. I had parents coming in to request it even after explaining my concern. I would end up starting 11 patients on it. Nine of the eleven parents came back looking to put their child back on stimulants because Strattera did not work well.
In addition, it had been studied in a small amount of patients. Rare side effects would not be readily apparent. After a year of use we found out several things. It was not as effective as stimulant medications. My patients told me that.
It had side effect like suicidal ideas in adolescents. Fortunately, there were not actually any suicides. It caused liver failure in three patients. Fortunately, the liver improved when the drug was discontinued. For these reasons, it got relegated to a second line medication for ADHD.
One thing that is relatively new in medicine is the popularity of tattoos. Tattoos have been around for thousands of years. However, the numbers have increased gradually. In 2012 about 21 percent of Americans had tattoos. Now the number is up to 30 percent. That is almost a 50 percent increase.
One of the things those increased numbers have allowed us to do is to look for rare side effects. We already know that some of the chemicals in tattoo inks can cause cancer. What we do not know is whether that makes any difference or not.
A June 2024 study in The Lancet Journal looked at this issue. They looked at about 12,000 individuals. Even this is a small number. About half of them had tattoos and the others did not.
Their overall findings were that individuals with tattoos had an increased risk of lymphoma. Lymphoma is a form of blood cell cancer. This was consistent with the fact that tattoo ink can be found in the lymph nodes draining the area of the tattoo.
One unusual finding was that the diagnosis of lymphoma appeared to have two peaks. One occurred within the first two years of receiving the tattoo. There was a lull between years five and eleven. Then the other peak occurred after 11 years.
One might think that there would be a higher risk with an increased number of tattoos. However, that did not seem to be the case. In addition, there did not seem to be a difference with the color of the tattoo. However, there were not enough patients to be sure about this factor.
One curious finding was that getting laser treatment to remove a tattoo actually increased the risk of lymphoma. The authors thought that this was logical since the laser treatment alters the cancer producing chemicals in the tattoo.
The biggest problem with this study is that it only looked at 12,000 individuals. Their final conclusion was that their findings indicated more studies of this sort need to be done. That would increase the total number of people looked at and thus the accuracy of the results. Perhaps more studies will show that this one just did not have enough of a population for accuracy.
The need for looking at more patients is not a lot different than my attitude toward using new drugs. The more people that are studied, the more accurate the results become.