During the past decade, a new class of drugs, called TNF inhibitors, has improved the lives of tens of thousands of people who suffer from painful autoimmune diseases including rheumatoid arthritis, psoriatic arthritis, and Crohn’s disease. But there is a catch: the same drugs that offer unmatched pain relief today might trigger a serious cancer later on. Patients desperate for new drug therapies are forced to make a difficult choice.

Now (at least for the 1.3 million adults with rheumatoid arthritis) that decision might be a little less daunting—although still not risk free. A new study, slated to appear in the November issue of Arthritis & Rheumatism, is one of the largest and longest popoulation-based looks at cancer risks associated with TNF inhibitors. Swedish researchers identified and analyzed data from 6,366 patients who started TNF inhibitors between January 1999 and July 2006. Then compared the data to more than 60,000 rheumatoid arthritis patients not taking any medications and 8,000 taking older drugs with different mechanisms of action.