"I'm in the middle of my program, and it's going along fine," Douglas, 65, told PEOPLE at a press conference for Wall Street: Money Never Sleeps on Sunday. "I'm very optimistic and hopeful right now."
He added: "My family has been very supportive. There's not a lot that anybody can do. You've just got to kind of do the program. But it's the world you [learn to] understand about cancer. You get to know cancer survivors, and the kind of support and outpouring I've been getting has just been amazing."
Despite his intensive course of radiation and chemotherapy to treat a tumor in his throat, Douglas said he has "a lot of things to be grateful for."
Among those things is his work. The new Wall Street film opens this Friday, and Douglas said he's "looking for a great opening night." He also credited costar Shia LaBeouf for being the heart and soul of the movie.
"He carries the movie," Douglas says. "I had to do that before, and I know the responsibility, but Shia carries every scene. It's a tremendous responsibility for anybody."