Will Reiser and Seth Rogen make a comedy about a brush with cancer. By Ben Kenigsberg.

Filmmakers tend to disavow autobiographical readings of their work, but when it comes to 50/50 – the story of a twentysomething Seattle radio writer (Joseph Gordon-Levitt) suddenly diagnosed with cancer – they can’t be helped. The movie was inspired by screenwriter Will Reiser’s own experiences after a tumour was found on his spine. The film loosely dramatises the way his life changed, especially with regard to his friendships, including his relationship with producer/co-star Seth Rogen.

And naturally, it’s a comedy. The humour, the two men say, was crucial. “That’s the reason we made the movie. Our experience was,
you know, it was sad and it was scary but it was really funny sometimes and we felt like that was unrepresented in movies,” Rogen, 29, explains. “There was no movie about a young guy who got cancer and his life didn’t completely stop and his attitude didn’t completely change.”

The two sat together on a couch at the Elysian Hotel in Chicago in late September, Rogen curled into a chilling-at-home pose, the lanky Reiser, 31, sitting up, a tad nervously. They have an easy rapport that’s half sales pitch, half reminiscence. (“I don’t think I ever got stoned with you until you were sick,” Rogen jokes to Reiser when the issue of medical marijuana comes up.)

There are elements of 50/50 that seem like formula and, indeed, Reiser stresses that the film isn’t an autobiography. He didn’t seek counselling or fall for a therapist like the one played in the movie by Anna Kendrick. Still, the duo felt that Reiser’s experience was tailor-made for a film, in ways one might not expect. “One of the reasons we thought he should write the movie in the first place is because he had followed the trajectory that a good movie character follows,” Rogen says. “He had improved himself through the experience. He was happier afterwards.”

When people would ask him questions about cancer, Reiser says: “It was clear that their impression of having cancer was based on movies they had seen like The Bucket List or Terms of Endearment, or just movies in which people basically die.”

Reiser, who got his break producing on Sacha Baron Cohen’s Da Ali G Show, found that even the aftermath of cancer – he had his surgery in June 2005 – didn’t go quite the way he anticipated. “There are some people who you do become closer to when you’re sick because there are some people who sort of thrive on helping people in need,” says Reiser, who is now cancer-free. “And then once you get better you kind of never hear from them again.” Rogen laughs: “We should have shown that.”

Up next: Rogen will direct a comedy written with his friend Evan Goldberg (who co-wrote Superbad with him and also served as a producer on 50/50) about the last night on Earth, called Apocalypse. “It’s about kind of realising you don’t like the people you’re friends with and the ramifications of being holed up in a small space with them for long periods of time,” Rogen says.

So the opposite of 50/50? “Yeah kind of. It’s an anti-friendship story.”

50/50 opens on Nov 17.