The 75-year old has told BBC News and The Guardian that he was diagnosed with stage three angioimmunoblastic T-cell lymphoma during the publicity tour for the latest Jurassic Park film, Jurassic Park: Dominion, in March last year.
He said writing his book, Did I Ever Tell You This?, helped him to cope with the diagnosis.
"I found myself with nothing to do," Neill said in The Guardian interview. "And I'm used to working. I love working. I love going to work. I love being with people every day and enjoying human company and friendship and all these things. And suddenly I was deprived of that. And I thought, 'what am I going to do?'
"I never had any intention to write a book. But as I went on and kept writing, I realised it was actually sort of giving me a reason to live and I would go to bed thinking, 'I'll write about that tomorrow … that will entertain me.' And so it was a lifesaver really, because I couldn't have gone through that with nothing to do, you know,"he said.
"The thing is, I'm crook. Possibly dying," he writes in chapter one, "I may have to speed this up."
Neill told The Guardian that he received chemotherapy at first but moved on to a new drug when the initial treatment failed.
He said he is now in remission, although will have to take the drug for the rest of his life.
19°C