While the Johnson & Johnson drug ustekinumab may be effective in treating moderate-to-severe psoriasis, it also may raise users' risk of cancer, the U.S. Food and Drug Administration warned Friday.

On its Web site, the agency said it probably needed to evaluate additional safety data before deciding whether the skin-disease drug increased the likelihood of cancer, the Wall Street Journal reported.

"The is a question whether a larger number of subjects, followed for longer periods might better inform the long-term safety of use of ustekinumab," the agency said.

An FDA advisory committee of experts on Tuesday is scheduled to decide whether to recommend whether to approve the drug, the newspaper said. The full agency isn't bound to follow the recommendations of its expert panels, but generally does.