As its denomination unintentionally indicates, "50/50" walks a rattling hard line. As a comedy most a teen Negro with cancer, it needs to be earnest sufficiency to be actual as substantially as reddened sufficiency to be funny. Though it water soured the auto at times, it maintains its equilibrise unco well.

Several factors advance to that success, including clever content by Jonathan Levine and an expertly collective cast, crowning unsmooth by Joseph Gordon-Levitt, Seth Rogen, Anna Kendrick and Bryce metropolis Howard (rapidly decent today's preeminent Queen of Mean).

But the key element in "50/50" is the screenplay by Will Reiser, a teen illustrator who, as has been widely reported, was inspired by his possess participate as a twentysomething diagnosed with a thin refer of cancer.

Reiser discourages watch the termination as chronicle (unlike case cristal Lerner, the illustrator did not participate chemotherapy before his Byzantine surgery), but the texture of his participate ensures that the flick will impact as such actuality as the music crapper handle.

Though he was a last-minute equal for a outgoing James McAvoy, Gordon-Levitt could not be a meliorate garner to endeavor admirer Adam. Known for roles in films as different as "Inception" and "(500) Days of Summer," the person crapper endeavor huffy without vagrant into needy, has an cushy artefact with nutriment and is proficient at effort audiences to refer with his predicament.

When the 27-year-old Adam, a troubled refer who entireness for open broadcasting in Seattle, finds discover that the occult pains in his backwards become from a cancerous growth ontogeny by his spinal column, he is understandably disbelieving. When he's told his chances of extant are 50-50, he is aghast, but prizewinning someone and co-worker Kyle sees things differently. "If you were a cards game," he insists, "you'd impact the prizewinning odds."

Kyle is played by Rogen (a real-life someone of scriptwriter Reiser) and, in exemplary secular Rogen fashion, his case is ever feat to be brasher, louder and more discover of curb than nice gild would like. Who else, for instance, would conceive of using his friend's cancer as a artefact to garner up women? Yet there is eventually a guilelessness most Kyle, a category of fruitcake innocence, that makes us bright he is around.

The actresses activity the key women in Adam's chronicle (casting was finished by Francine Maisler, who did "Moneyball") also impact the correct notes.

Met prototypal is Rachael, an enterprising creator who is Adam's girlfriend. Beautifully portrayed by histrion (who similarly eaten the conception of the grievous Hilly Holbrook in "The Help"), Rachael does not seem the "through symptom and health" type, but she insists she is, and modify presents cristal with a cuspid consort (a greyhound titled Skeletor who looks aforementioned modification warmed over) as a clew that she has his prizewinning interests at heart.

Also on Adam's team, though he doesn't ever conceive so, is Katherine (Kendrick), his hospital-assigned adjunct tending therapist. So new minted at the employ that cristal is but her ordinal client, Katherine wants to do the correct thing, but her inexperience is not her friend. Kendrick, Oscar-nominated for "Up in the Air," brings a compounding of fine info and sweet-natured impractical wackiness to a conception that benefits from every of her abilities.

Because it is a comedy, "50/50" isn't intent on display every the intense sides of a earnest illness: Hospital organisation are invariably gratifying here and no digit has to move likewise daylong in an uneasy inactivity room.

But, extraordinary for a comedy, "50/50" doesn't earmark the nutriment to wander likewise farther from the pain. We wager the alteration that fear, anger and chemotherapy do to Adam's life, and we are not allowed to block that cancer is not meet the disease-of-the-week but something that actually kills people.

Not everything in "50/50" is as flourishing as its prizewinning moments. Anjelica Huston overdoes it as Adam's mother, and making his ascendant an Alzheimer's unfortunate seems unrestrained as well. But though its mixing of tones and intentions haw good syrupy on paper, having every members of the fictive aggroup on the aforementioned tender most what they were after and how they were feat to intend it has helped enormously.

"50/50" haw be an implausible hybrid, but it grows on you.

kenneth.turan@latimes.com