Dr. Sanjay Gupta and Tour de France champion Lance Armstrong join forces at a Cancer Town Hall on “Saving Your Life” (7 p.m. today, CNN). Combining information and inspiration, “Saving” discusses ways viewers can prevent cancer and provides stories of people like Armstrong who have faced the disease and survived and thrived.

¢ When last seen, “24” (7 p.m. Sunday, Fox) hero Jack Bauer (Kiefer Sutherland) was on a very slow boat to China. That was then. After a 20-month absence, Jack’s back and ready to save a world that has never faced so much danger.

It would be remiss to reveal too much here. It’s safe to say that this season does not open with the slam-bang action of last year’s “24.” But having seen the first four hours (unfolding Sunday and Monday nights), I can only advise fans: Don’t miss a single minute. And schedule plenty of time for around the water cooler on Tuesday morning. You will be talking about nothing else.

Peter MacNicol (“Ally McBeal”) joins the cast as reptilian presidential adviser Thomas Lennox, a hardliner who believes the government has the right and obligation to round up aliens and dissidents in a time of crisis. Newly elected President Wayne Palmer (D.B. Woodside) seems a tad uncertain, and he makes a series of transparently bone-headed decisions that seem more about advancing the plot than saving the nation.

Meanwhile, at CTU, Chloe (Mary Lynn Rajskub) continues to provide odd comic relief as the referee between her cranky ex-husband, Morris (Carlo Rota), and Milo (Eric Balfour), a freelancer Chloe once dated and who appeared briefly on an earlier season of “24.” I’m not sure I like a CTU where Chloe is one of the “grown ups,” but the season is young.

¢ Ricky Gervais’ odd and addictive series “Extras” (9 p.m. Sunday, HBO) also returns for a second helping. Andy Millman (Gervais) has graduated from anonymous stand-in to potential sitcom writer and star. But fame has its own grim rewards. Andy’s dream of a slice-of-life comedy turns into a wretchedly dated Britcom (“When the Whistle Blows”) that critics hate and audiences embrace as a kind of time-warp guilty pleasure.

“Extras” continues its tradition of A-list cameos. Tonight, a vain Orlando Bloom hits on Maggie (Ashley Jensen) and explains why he’s a better kisser than Johnny Depp.

Next week, David Bowie appears in a brilliant turn that viewers dare not miss. He does something utterly unexpected yet perfectly in keeping with his public persona and this show’s theme of exquisitely painful humiliation. While a short scene, it’s quite unforgettable – a little diamond that viewers should lock away in their memories.

Tonight’s highlights

¢ New Orleans hosts Philadelphia in the NFC divisional playoffs (7 p.m., Fox).

¢ Jake Gyllenhaal hosts “Saturday Night Live” (10:30 p.m., NBC), featuring musical guests the Shins.

Sunday’s highlights

¢ Scheduled on “60 Minutes” (7 p.m., CBS): an interview with the parents of the students involved in the Duke lacrosse-team scandal.

¢ Auditions continue on “Grease: You’re the One That I Want” (7 p.m., NBC).