The U.S. Food and Drug Administration on Wednesday announced a safety review of several drugs known as tumor necrosis factors, or TNF blockers, as they might lead to cancer in children and young adults.

The drugs included in the investigation are infliximab (Remicade, Johnson & Johnson), etanercept (Enbrel, Amgen and Wyeth), and adalimumab (Humira, Abbott Laboratoties).

These drugs are used to treat one or more of a number of immune system diseases, including juvenile idiopathic arthritis, rheumatoid arthritis, psoriatic arthritis, plaque psoriasis, Crohn’s disease and ankylosing spondylitis.

In addition, a 10-year study will be conducted to assess the long –term risks of certolizumab pegol (Cimzia, UCB Inc), a THF blocker recently approved to treat Crohn’s disease in adults.

All these drugs work by blocking the activity of TNF, a substance in the body that can cause inflammation and lead to immune system-related diseases.

The safety review follows about 30 reports of cancer from the past 10 years in children and young adults taking the so-called TNF blockers. Half of the reported cancers were lymphomas, including both Hodgkin’s and non-Hodgkin’s lymphoma. Other cancers included leukemia, melanoma and cancers of various organs.

“The drugs Enbrel, Humira and Remicade are being reviewed for a possible association between their use and the development of lymphoma and other cancers in children and young adults treated with TNF blockers for juvenile idiopathic arthritis, and Crohn’s disease,” the FDA said in a statement on their Web site.

Until the investigation is complete, the FDA said, “health care professionals and caregivers should be aware of the possible association of lymphoma and other cancers in children and young adults when deciding how to best treat this population.”

The FDA investigation could have a big financial impact on the drugs’ manufacturers. For example, Humira was Abbott’s best-selling product last year with over $3 billion in sales, while Remicade had sales of $1.65 billion.