He was first diagnosed with cancer in 2018, but kept it private for three years.
James revealed his cancer diagnosis earlier this year in an interview with the US Today show, just weeks after the much-hyped Friends reunion aired - which had left fans wondering as to why he wasn't included in the live filming.
He explained that his former castmates were aware of his health battle and that his chemotherapy treatment had prevented him from taking part in person.
"I wanted to be a part of that, and initially I was going to be on the stage, at least, with them, and be able to take part in all the festivities," Tyler said in the interview in June.
"It was bittersweet, honestly. I was very happy to be included. It was my decision not to be a part of that physically and make an appearance on Zoom, basically, because I didn't wanna bring a downer on it, you know? I didn't want to be like, 'Oh, and by the way, Gunther has cancer'."
Tyler said that he was initially diagnosed back in September 2018, but that the disease had since spread to other parts of his body, including his bones and spine, which had left his lower body paralysed.
"I was diagnosed with advanced prostate cancer, which had spread to my bones," he said. "I've been dealing with that diagnosis for almost the past three years … It's stage 4. Late stage cancer. So eventually, you know, it's gonna probably get me."
Tragically, Tyler said the Covid pandemic meant he missed a regular check with doctors, during which time the cancer started "mutating".
He said his cancer wasn't caught early and was only detected during a routine check up three years ago. The cancer then started to spread to his bones and spine, which led to him being paralysed in his lower body.
"It's made me, personally, just realise how important every moment is, every day," Tyler said. "Don't give up. Keep fighting. Keep yourself as light as possible. And have goals. Set goals. My goal this past year was to see my 59th birthday. I did that, May 28th. My goal now is to help save at least one life by coming out with this news.
"That's my only reason for coming out like this and letting people know … Next time you go in for just a basic exam or your yearly check-up, please ask your doctor for a PSA test. It's easily detectable."
Tyler appeared in several big shows across his decades-long career, including Sabrina, the Teenage Witch, Scrubs and Just Shoot Me! but was best known for his long-running stint as Gunther, who appeared in 150 episodes of Friends.
