Study ties chronic acetaminophen use to blood cancers

Reuters reports on a new study that ties excessive use of the painkiller acetaminophen (Tylenol) to an increased risk of blood cancers. Then, in the second paragraph, the story reflects some of the current frustration involved in getting any kind of straight answer out of studies like this. "Yet the risk remains low, and it's still uncertain what role the drug plays," Reuters reports.

The problem is that this, and previous, studies do not produce a direct causal link. Acetaminophen could be simply an "innocent bystander," while those who take a lot of painkillers are doing so do deal with the possible beginning stages of cancer. Still, this new study is considered stronger than previous ones because it tracked a large population of healthy people over time. "We have the first prospective study," researcher Emily White, of the Fred Hutchinson Cancer Research Center in Seattle, told Reuters Health.

The researchers followed 65,000 cancer-free older men and women in Washington state. Over the course of six years, less than one percent developed a blood cancer such as lymphoma and myelodysplastic syndrome. Of those, more than nine percent used high amounts of acetaminophen. The researchers found that, after accounting for things like age, arthritis and a family history of certain blood cancers, chronic acetaminophen users had nearly twice the risk of developing the disease, Reuters reports.

"A person who is age 50 or older has about a one percent risk in 10 years of getting one of these cancers," White told Reuters. "Our study suggests that if you use acetaminophen at least four times a week for at least four years, that would increase the risk to about two percent." White also points out, though, that long-term use of any drug could have adverse effects and, as always, "You have to weigh the benefits against the risk of all the drugs."

- read the Reuters report
- and see the study in the Journal of Clinical Oncology