As musical numbers go, this one — you should pardon the term — kills.

It comes some 20 minutes into “Turning Thirty,” Atlanta resident Tom Willner’s tuneful dramedy about his battle with testicular cancer. Up to this point, the show hasn’t been total doom and gloom— indeed, one particularly rollicking early ditty is the not so slyly named “Have A Ball.”

Still, enough doctor’s visits and intimations of mortality already have cropped up for audience members to do double takes when a character named TC takes center stage to belt out, “The Best Job in the World.”

That sizzling intro, featuring plenty of jazz horns and finger-snapping. The slinky, come-hither suggestiveness of lyrics like, “People think that I’m awful/But I don’t see it that way,” crooned by an actress (Pam Duncan) who sees her character as “a combination of [Cabaret’s] Joel Grey and Samantha from ‘Sex and the City.’ ”

Are we being wooed?

By a potentially fatal disease, of all things?

“I wanted to make cancer a character,” said Willner, 40, who’ll present a “cut down” version of the show (mostly music, fewer acting scenes) on Oct. 9 as a fund-raiser for the American Cancer Society at its national headquarters overlooking Centennial Olympic Park.

Originally envisioned as a tuxedoed “showman” or a brutal dictator, TC gradually evolved into a subtler, more provocative character, Willner explained. “I kept thinking, how would this disease live with itself? It must see itself differently from how others see it. It thinks it’s actually doing good [by] being around.”

Seeing things differently is the guiding principle behind “Turning Thirty,” which attempts to do for cancer what the Tony Award-winning musicals “Next to Normal” and “Rent” did for bipolar disorder and people living with HIV, respectively.

Set it to music.

“People say, ‘You’re singing about cancer, it will be a downer,’” said Willner, a veteran singer-songwriter (his latest CD is entitled “Rescue Me”) who wrote all 17 original songs in “Turning Thirty. “And the whole time I’m thinking, it’s testicular cancer. C’mon, folks, the jokes write themselves!”

Still, most “folks” handed a cancer diagnosis days before their 30th birthday likely would spend the bulk of their time weighing different treatment options and wondering, “Why me?” Willner did that and more, penning the eventual lyrics to songs about the vagaries of fate (“Your Number’s Up”), the gutwrenching horrors of chemotherapy (“Poison”), and another one whose title we can’t print in a family newspaper.

“Turning Thirty’s” main character, “Conlan,” clearly is channeling his creator when he opens the show by singing, “I got logic on my left side, but an artist on my right.” A graduate of Rensselaer Polytechnic Institute with degrees in electrical engineering and computer arts, Willner is director of information delivery for the American Cancer Society, a job that — talk about the vagaries of fate — he was hired for several years before his own cancer diagnosis. But he also grew up playing guitar and piano and began writing songs as a teen.

So Willner was only doing what came naturally when he began keeping a journal after he discovered a small lump on his testicle. At some point during his year-long odyssey of five surgeries, four rounds of chemotherapy, one recurrence of cancer and — back to that unmentionably titled song — a ruefully funny visit to a fertility clinic, his logical side recognized what his artistic one was up to.

“It started out as therapy for me, but it was quickly becoming more like a play,” Willner recalled about his writing bouts. “And then, a full musical.

It’s his first one and, admittedly, still a work in progress. “Turning Thirty” debuted last fall as a one-time-only benefit performance for ACS at Druid Hills United Methodist Church. A narrator set each scene and Willner (aka Conlan) played a piano onstage while some other performers read from pared-down scripts. Nearly all of the original cast will appear again in next month’s show (the third public outing for “Turning Thirty”), having crossed paths musically and otherwise with Willner over the years (Kristi Budd and Jose Cordero, who play Conlan’s wife and doctor, respectively, both teach kindergarten at Paideia School, which Willner’s children used to attend; now, Budd and Willner regularly perform together in Urban Blue, a band that plays everywhere from Eddie’s Attic to private events).

Willner, who’s remained cancer-free for nearly a decade, joked that last fall’s debut performance of the play came about because he was “determined to do ‘Turning Thirty’ before I turned 40.” But he clearly has bigger dreams for the musical. Next up, he hopes to interest a local or community theater group in producing it, so “we can expand upon what we’ve written and tweak what does and doesn’t work. And after that, an even larger theater company.”

And after that?

“Ultimately, I want everyone who sees it to be entertained, and anyone going through cancer to know there are others out there like them,” Willner said sincerely, just before breaking into a broad grin. “And I want theater companies in New York and L.A. to be clamoring to put it on!”

The odds are steep. The theater world has traditionally viewed malady as a subject more fit for weighty drama than musicals. In 1999, Atlantan Margaret Edson won a Pulitzer Prize for her draining, off-Broadway play about a scholar of John Donne’s poetry who is dying of ovarian cancer. Last spring, Jane Fonda returned to Broadway after a 46-year absence and snagged a Tony nomination for her tense turn as a musicologist with late-stage ALS (aka “Lou Gehrig’s Disease”) in “33 Variations.” And the somber list goes on, from “Angels in America” (AIDS) and “The Elephant Man” (Neurofibromatosis) to “Whose Life Is It Anyway” (paralysis) and “The Shadow Box” (about terminally ill hospice patients).

Yet audiences tend to be more squeamish when it comes to life-and-death topics being given the song-and-dance treatment. That’s something the creative team behind “Next to Normal” wrestled with along the way to winning 2009 Tony awards for best leading actress and original score in a musical. When early audiences seemed insufficiently moved by the main character’s struggle with bipolar disorder, they eliminated several more humorous musical numbers.

Yet patrons can find something equally discordant about a musical that’s too serious. At least that’s what Samuel Wessels heard when he began writing songs about his experiences as a leukemia patient.

“My mom just said to make sure that it was funny, because no one wants to watch a depressing musical,” related Wessels, a 2008 University of Utah graduate whose show, “Sam I Was,” went through several weeks of workshop performances in June at the Yale Institute for Music Theatre. “I try to make clear from the first scene that this is a comedy, that you’re allowed to laugh. But then there are songs by Sam, Mom and Dad that are tear-jerkers and are meant to pull you out of your laughs and into the reality of what could have been a terminal disease.”

Similarly, Willner’s score packs emotional wallops along with punch lines. “Sometimes,” a thoroughly honest examination of the range of emotions from resentment to despair that a person goes through when a loved one is seriously ill, ends with Budd singing barely above whisper level, “Dear God, what am I to do/This horrible nightmare is killing me too.”

And while Willner’s own medical story is personal, he says, the show’s message is universal.

“It’s about having kids, getting older and gaining perspective,” Willner said. “If you flip around that question about how does cancer live with itself, you end up with looking at what’s most important about the life you’re living.

“You don’t have to get cancer to have a ‘Turning Thirty’ experience.”