Former NBA player Jason Collins is undergoing treatment for a brain tumor, the NBA announced on Thursday.

“Jason and his family welcome your support and prayers and kindly ask for privacy as they dedicate their attention to Jason’s health and well-being,” the league said in a statement.

A 7ft center, Collins played eight of his 13 seasons with the New Jersey/Brooklyn Nets and also spent time with the Atlanta Hawks, Boston Celtics, Memphis Grizzlies, Minnesota Timberwolves and Washington Wizards.

Collins averaged 3.6 points and 3.7 rebounds in 735 games from 2001-14. He was drafted with the 18th overall pick by the Houston Rockets in 2001 after starring at Stanford alongside his twin brother, Jarron. He retired from the NBA in 2014.

Collins made news off the court when he came out as gay in 2013 in a Sports Illustrated article. He was the first active male athlete from one of the four major men’s North American professional sports leagues to do so publicly.

“I didn’t set out to be the first openly gay athlete playing in a major American team sport,” Collins wrote in his article for Sports Illustrated. “But since I am, I’m happy to start the conversation. I wish I wasn’t the kid in the classroom raising his hand and saying, ‘I’m different.’ If I had my way, someone else would have already done this. Nobody has, which is why I’m raising my hand.”

Since his retirement from playing, the 46-year-old has worked for the NBA as an ambassador. He married his long-term partner, Brunson Green, earlier this year.