The FDA has issued a warning that TNF blockers (including Enbrel, Humira, Remicade and others) may cause lymphoma, leukemia and other cancers in children and teens. This is in addition to the "black box" cancer warning such medications already carry. 

You can read it from the FDA’s website here: FDA:

       Cancer Warnings Required for TNF Blockers

And this is the information they offer to healthcare providers:

       Information for Healthcare Professionals

These medications certainly still have their uses, but a very large number of people who are currently on Biological meds could probably be seeing good results with narrowband UVB phototherapy instead, without such established links to cancer and without stressing the internal organs.

Treat lightly instead…