FDA Starts Safety Review of Autoimmune Disorder Drugs

And then there's the conflicting scientific evidence. One 2006 study reported that concerns about TNF blockers causing cancer were unfounded. But earlier this year, a review of the research concluded the risk may be real.

"TNF plays an important role in immune surveillance and, by blocking it, you might be interfering with the body's own defenses," Putterman said.

The FDA has requested that makers of TNF blockers approved for use in children and young adults supply information about all reported cases of cancer in children and young adults taking the drugs.

The maker of Cimzia, UCB Inc., must conduct a study looking at the long-term risks of this drug. That study will begin in 2009, and will take about a decade to complete.

In the meantime, the FDA has asked health-care professionals to weigh the possible risks against the benefits when prescribing TNF blockers.

More information

Read about TNF blockers U.S. Food and Drug Administration.

SOURCES: Chaim Putterman, M.D., chief, division of rheumatology, Montefiore Medical Center and Albert Einstein College of Medicine, New York City; Stephen Lindsey, head, rheumatology, Ochsner Health Service, Baton Rouge, La.; June 4, 2008, U.S. Food and Drug Administration statement