What would you do if, in your prime years of young adulthood, you developed a rare and deadly form of cancer and lived to tell the tale? In Will Reiser’s case, write a semi-autobiographical screenplay and get the guys responsible for “Superbad” behind it. Directed by Jonathan Levine, “50/50” is a touching dramedy starring Joseph Gordon-Levitt as Adam, a 20-something public radio writer determined to beat the odds of his disease.

An avid runner, Adam initially goes to the doctor for debilitating back pain but finds his life turned upside down when test results reveal a cancerous tumor growing along his spine. Referred to inexperienced psychiatrist-in-training Katie (Anna Kendrick) to help cope with the emotional aspect of the diagnosis while undergoing aggressive chemotherapy treatment, Adam embarks on the uncertain road to recovery. While he first greets his predicament with a numbness that Katie reassures him is normal, the inevitable changes in his health and their impact on his personal life force him to examine his choices and relationships in new ways.

The first casualty is Adam’s pretentious artist girlfriend Rachael (Bryce Dallas Howard), whose wavering support leads him to rely, more than ever, on the other influential figures in his life. This primarily includes his best friend Kyle (Seth Rogen), whose questionable plans for using Adam’s disease as a way to pick up girls provide some much-needed comic relief. But also, with Katie’s encouragement, Adam finally reconnects with his overprotective mother Diane (Anjelica Huston) despite not wishing to tell her about his cancer in the first place.

There is no doubt that “50/50” is supremely cast with solid performances, although one could argue that it is simply a function of the actors portraying familiar roles. Rogen, for example, reprises his crass sidekick persona, just as Kendrick’s performance echoes the well-intentioned Type A that garnered her Academy Award nomination for “Up in the Air.” Huston and Howard are strong in their supporting roles, with the latter (who most recently appeared in “The Help”) continuing her streak of bringing humor and humanity to unlikable characters.

Gordon-Levitt gives a moving performance as a young man trying to come to terms with the fact that, no matter what he or anyone else does, he might not survive but at times feels overshadowed by the other characters. This is less an issue with the acting than the writing and, in the end, Adam’s subtleties better enable the audience to identify with him, which in turn makes the film all the more poignant.

As per the common tragedy that often befalls comedies these days, overzealous marketing has ruined the potential hilarity of certain scenes in the film, but luckily Reiser’s witty script still has plenty of tricks up its sleeve. “50/50” is very much the “cancer comedy” that its PR team would have you believe but, just a heads up: bring some tissues, because there will probably also be some tears, and I don’t mean the kind that result from laughter. Reiser and Levine’s treatment of what is now one of the leading causes of death worldwide successfully balances sincerity, humor and deprecation, resulting in a truly heartfelt and inspirational story.