Thorson documented the shearing of his famous locks and shared the emotional footage with ET, seen in the clip above.
"I don't think anyone enjoys being sick," Thorson told McLarty. "But I've got a great chance. I'm going to beat this, and I'm not going to let it get me down."
Matt Damon will play Thorson in the upcoming HBO TV movie, Behind the Candelabra, based on Thorson's book of the same name. Michael Douglas, a cancer survivor, will star as Liberace.
"Michael was amazing," said Thorson when asked if Douglas' battle has inspired him. "We didn't think this film was going to get made let alone have him survive stage 4 throat cancer. I'm just very honored..."
Thorson plans to re-release the book to coincide with the movie release. Watch the video for more.