Former NBA player Jason Collins announced that he is undergoing treatment for Stage 4 glioblastoma in an interview with ESPN’s Ramona Shelburne that was released Thursday. Glioblastoma is one of the most severe forms of brain cancer.

Collins, who played for six teams in a 13-year career, came out in 2013 as the first openly gay active player in NBA history.

His family announced in September that he was dealing with a brain tumor, but no additional details were provided. In his conversation with Shelburne, Collins pointed out that his family respected his wishes to wait until he was able to speak about his condition. He said he began feeling symptoms this past summer, and in August, he found himself unable to pack for a trip to the US Open. A CT scan revealed a brain tumor and Stage 4 glioblastoma.

“According to my family, in hours, my mental clarity, short-term memory and comprehension disappeared — turning into an NBA player’s version of Dory from ‘Finding Nemo,’” Collins said. “Over the next few weeks, we would find out just how bad it was.”

Collins’ tumor cannot be safely operated on. He has undergone radiation treatment and also taken a drug called Avastin to stop the growth of the tumor.

“Because my tumor is unresectable, going solely with the ‘standard of care’ — radiation and TMZ — the average prognosis is only 11 to 14 months,” Collins said. “If that’s all the time I have left, I’d rather spend it trying a course of treatment that might one day be a new standard of care for everyone.”

Collins said he wanted to approach his diagnosis in a similar way to how he came out as gay — on his own terms.

“I wasn’t worried it would leak before the story came out, because I trusted the people I told,” Collins said. “And guess what? Nothing leaked. I got to tell my own story, the way I wanted to. And now I can honestly say, the past 12 years since have been the best of my life. Your life is so much better when you just show up as your true self, unafraid to be your true self, in public or private. This is me. This is what I’m dealing with.”

Growing up in Southern California, Collins and his twin brother, Jarron, committed to play college ball at Stanford. After four years with the Cardinal from 1997-2001, including an All-American senior season, Collins was a first-round pick of the Houston Rockets in 2001. He went on to play eight years for the New Jersey (and later Brooklyn) Nets and played for six teams over his 13 seasons. He retired in 2014.

In his interview with Shelburne, the 47-year-old described a scary fall at home in Los Angeles, just a week before his hospital visit. Collins was determined not to be found on the floor.

“All I could think while I was down there was, ‘This is not how you’re going to find me. I’m not going to be like Elvis on the toilet,’” Collins said. “If something goes bad here, this is not how you’re going to find me. I’m going to figure out how to solve this puzzle. If I don’t panic, I will figure this out. I will get myself up.

“You’re reading this now because I eventually got myself up and figured it out. Anyone who knows me knows not to underestimate me on this, either.”