'50/50's' Seth Rogen Reveals 'Most Challenging' Part of Filming (Video)

What was the toughest part about filming cancer comedy 50/50?

our editor recommends

'50/50:' What the Critics Are Saying About Seth Rogen, Joseph Gordon-Levitt's New Movie

'50/50': How Joseph Gordon-Levitt Signed on Cancer Comedy at Eleventh Hour (Video)

Coming up with the title, admits Seth Rogen and screenwriter Will Reiser in a roundtable interview (that also features co-stars Joseph Gordon-Levitt, Anna Kendrick and Bryce Dallas Howard). Watch below.

VIDEO: Watch Seth Rogen and Joseph Gordon-Levitt in '50/50' Trailer

"The most challenging part was undoubtedly coming up with the title," says Rogen of his film, which opens in theaters Friday.

Added Reiser, who wrote the script based on his own spine cancer diagnosis when he was in his 20s, "It was the most stressful aspect of making the movie."

PHOTOS: Seth Rogen: Unlikely Superhero

Gordon-Levitt also discussed his joining the movie late after James McAvoy dropped out.

50/50: Toronto Film Review

"I had to read and decide right away. They were already four days into production," he said.

Joked Rogen, "We gave him 90 minutes to read the script. It was in real time!"