The Food and Drug Administration said Tuesday it is investigating a possible link between the onset of childhood cancer and the use of arthritis drugs made and sold by Johnson and Johnson and Amgen Inc.

The FDA said it found 30 cases of lymphoma, or immune-cell cancer, in patients under 18 who took Amgen’s Enbrel and J & J;’s Remicade.

“While the review is ongoing, FDA advises prescribers to weigh the possible association with lymphoma and other cancers against the benefits of treatment when prescribing TNF blockers to children and young adults,” the FDA said in a statement.

The family of drugs is currently approved to treat childhood arthritis and Crohn’s disease, the FDA said.

“Amgen and Wyeth are committed to the safety of patients and have consistently updated the product labeling for Enbrel over the past decade,” the two companies said in a joint statement Wednesday. “The companies maintain ongoing safety surveillance programs worldwide to analyze and evaluate safety reports … Amgen provided the FDA with information from both companies’ adverse events databases and is continuing to work with the Agency to evaluate the overall risk benefit of ENBREL in pediatric patients.”

Enbrel is one of Thousand Oaks-based Amgen’s biggest selling drugs, bringing in $5.3 billion last year in sales. Amgen partnered with Wyeth in the development and marketing of Enbrel.

This comes after sales of Amgen’s anemia drugs, Aranesp and Epogen, decreased 25 percent and 11 percent, respectively, in the first quarter of this year with experts expecting further declines. Anemia drugs accounted for more than $4 billion in sales for Amgen last year.

Shares in Amgen were up 30 cents to $44.45 in early trading Wednesday.