Is acetaminophen linked to blood cancer?

Taking lots of acetaminophen — the active ingredient in over-the-counter medicines like Tylenol — increases your risk of getting blood cancer, a study published in yesterday's online edition of the Journal of Clinical Oncology found.

The research is the first large prospective study on the issue, looking at nearly 65,000 men and women in Washington State ages 50 to 76 who participated in the Vitamins and Lifestyle Study. They found that frequent users of acetaminophen — those who took it over four days a week, for more than four years — doubled their chances of getting blood cancer in the next 10 years, including myeloid neoplasms, non-Hodgkin lymphomas and plasma cell disorders. There wasn't a change in people who took asprin, nonasprin NSAIDs, or ibuprofen.

However, the risk is still small, increasing from one percent for the average population to two percent for frequent acetaminophen users, say researchers. Also, the study showed an association between heavy acetaminophen use and the increased cancer risk, but didn't prove that the former causes the latter. The researchers also also pointed out that more studies are necessary before anyone recommends reviewing what's in your medicine cabinet.