The Charlotte Observer reported Thursday that, according to sources, Anderson had a positive drug test in May. He already was under suspension for a similar offense, which caused him to miss the 2002 campaign.
The paper said the latest offense means he likely will miss the 2003 season as well because his status is not expected to be re-evaluated by the league until December.
"We're just moving on with getting ready for training camp," General Manager Marty Hurney told the paper. "There's nothing we can do about that at this point."
Anderson was the Panthers' No. 1 draft pick in 2000. His 94-yard fumble return against the New York Jets on Oct. 28, 2001 was his first NFL score. He posted career-highs of nine starts and 48 tackles in 2001.