It seems almost cruel to cast the endlessly-energetic Joseph Gordon Levitt in the new cancer comedy 50/50. Joseph is the anti-slacker. The actor/producer/musician is one those multi-tasking wonders who makes Shia LaBeouf look like Rob Schneider. Which is why the producers of 50/50 were thanking their lucky stars when the original lead of 50/50 - James McAvoy - had to drop out two weeks before cameras were set to roll and it turned out JGL was there to step in.

JGL has quietly built up an impressive body of work, from his unflappable appearance in Inception, to the bittersweet love story 500 Days of Summer or hidden gems like the high school noir Brick. In 50/50, Gordon-Levitt plays Adam, an intense radio producer diagnosed with a rare form of cancer. The screenplay was originally titled I'm With Cancer but producers decided the c-word would hurt ticket sales. It turns out 50/50 is more about how Adam's diagnosis affects the people around him. Seth Rogen plays his buddy Kyle, who's struggling to put a positive spin on the ultimate buzz kill. Adam's girlfriend Rachel (Bryce Dallas Howard) is shaken but stands by her man, while Adam himself bounces between shock and self-pity. Anjelica Huston also appears as Adam's justifiably mortified mother.

Joseph Gordon Levitt and Seth Rogen are best buddies in 50/50. (TIFF)

The comedy cocktail 50/50 would be equal parts anger and absurdity, which comes from screenwriter Will Reiser's own story of survival. At 24, Reiser was diagnosed with cancer while working as a producer on the Da Ali G Show. As Reiser began to recover, he and his friend Seth Rogen starting talking about capturing the surreal nature of dealing with cancer as a young man. Many years and drafts later, 50/50 came into being.

Stylistically 50/50 belongs in the recent indie-feel-good genre. The coffee culture of Seattle and the late '90s soundtrack fit as comfortably as the argyle sweaters Adam prefers. What saves 50/50 from becoming 500 Days of Cancer is the trio of lively performances. First, rather than a treacle like My Life, 50/50 serves up a bromance of sorts between JGL and Seth Rogen. Rogen goes back to doing what he does best here, playing the same kind of easy-going jokester we saw in Knocked Up. While it's certainly not a stretch, Rogen's laid-back, loose style plays off JGL's buttoned-down persona nicely and results in an honest snapshot of two dudes dealing with death. Adding some zaniness of her own is Anna Kendrick as Adam's therapist Katherine. As young Doctor Katherine, she's all too human, blurring the lines between patient and doctor immediately. Like JGL, Kendrick has a laser-focused nerdiness that sets her apart. Together the two make an intriguing pair, pushing and pulling, slowly finding a way forward together.

Although the all-too obvious subplot concerning the lack of affection between Adam and Rachel robs 50/50 of much of its momentum, the film makes up for it in the end. When he's facing a possibly dire diagnosis, Adam's usually placid appearance cracks wide open. It's a messy, scary moment that rings true.

Rating: Three-and-a-half wool toques out of five.