“As funny as cancer” has long been a brutal way of indicating that something fails to amuse. Undeterred by the challenge, Showtime launches “The Big C” (9:30 p.m., Showtime), a new comedy starring Laura Linney as Cathy, a Minnesota teacher, wife and mother who confronts her terminal diagnosis with resilience and spunk.

If great casts guaranteed success, “C” would be in line for a bouquet of Emmys. In addition to the always remarkable Linney, Oliver Platt stars as her bewildered husband, Paul, and “Precious” star Gabourey Sidibe appears as Andrea, a promising student who resists Cathy’s attempts at bribery and mentorship.

Unfortunately, “The Big C” follows Showtime’s habit of reducing really big issues (“Weeds,” “Californication”) to glib, throwaway dialogue uttered by characters too smug and unrealistic to care about.

The notion of turning a death sentence into a moment of empowerment is intriguing, but Cathy’s acts of self-assertion smack of someone who wants to meet her maker as a selfish 13-year-old. She hides her diagnosis from the clueless Paul, who eventually believes she’s having some kind of affair with her doctor.

Cathy is matched in outsized self-assertion by her brother Sean (John Benjamin Hickey), a former business big shot who has become a kind of suburban crank and crusader. He appears shirtless in front of car dealerships railing against SUVs and grosses out fast food diners by eating from the garbage can. The local kids, including Andrea, call him “Jesus” and avoid him on sight.

You don’t have to have lived with cancer to find “The Big C” unlikable in the extreme. Barely a moment rings true, even as satire.

• Look for Richard Dreyfuss to appear in four episodes of “Weeds” (9 p.m., Showtime), now entering its sixth season.

• Cable imitation strikes again with TRU’s new series “Hardcore Pawn” (9 p.m. and 9:30 p.m., TRU), set in a family-run pawn shop, not unlike History’s “Pawn Stars.”

• “Animal Planet Investigates” (9 p.m., Animal Planet) looks at “Gang Dogs,” animals mistreated from birth and trained for fighting and intimidation by criminal organizations.

Tonight’s other highlights

• The Jets host the Giants in preseason NFL football (7 p.m., ESPN).

• A peculiar police poster is deconstructed on “History Detectives” (8 p.m., PBS, check local listings).

• Pope accentuates public relations on “The Closer” (8 p.m., TNT).

• A birthday surprise leaves one camper upset on “Huge” (8 p.m., Family).

• A deadly contagion looms on “CSI: Miami” (9 p.m., CBS).

• “Anthony Bourdain: No Reservations” (9 p.m., Travel) visits Rome.