It's billed as the classic Southern childhood -- 11 brothers and sisters, eccentric piano teacher and spooky neighbors. All are part of the true story of actress and solo performer, Liza Vann.

As outlandish as her Southern upbringing may have been, it hardly prepared her for her adult struggle with breast cancer, a theme tackled as well in her solo, The Top of the Bottom Half. The autobiographical show, in which Vann plays several characters from her life, returns March 4-8 to the Theatre at St. Peter's Church, 619 Lexington Ave. in Manhattan.

Co-written with Katherine Griffith, Half is subtitled, "The Keeper of All Knowledge: Take Two." The show has played across the U.S. and Canada, including a St. Peter's run last season.

Andrew MacBean, who staged Nine in London, was scheduled to direct but left the production before rehearsals began due to other commitments in London. Now directing is Barry McNabb, who's most closely associated with Off-Broadway's York Theatre Company.

Over lunch at P.J. Clarke's Restaurant on midtown's east side, Vann explained that the show's title referred to the order of her birth. "I was number seven out of 12 children -- the top of the bottom half." After those early years, Vann went the fairly typical acting route. She graduated with a degree in dramatic arts from Queens College (that's North Carolina, not New York), and then came to Manhattan, where she worked steadily off and off-off-Broadway. In recent years, she turned to producing independent films, including 1990's The Radicals.

None of this prepared her for the news, five years ago, that she had breast cancer. But Vann was far from a timid victim or shrinking violet. In fact, she rails against women who all-too-easily sacrifice their breasts because doctors convince them that's the wisest treatment.

"Rule number one in life," says Vann, "you are the only one at the table. Everyone else comes and goes, but you are the constant. Most doctors have an agenda or a juggernaut mentality. `We're gonna get this cancer and cut it out.' It's up to you to stay involved with the whole process, including the incision, the cosmetic, the treatment, the interior and the exterior. I've heard so many people say, out of sympathy, `I'll give up my breast to save my life' -- but have they really gone step-by-step through all the options? How about looking for reasons not to be scarred. Removing a breast is not just like screwing out a lightbulb."

Van even points up the great myths about chemotherapy (which she underwent): you don't always need it, and you don't have to lose your hair. "Chemotherapy is shotgun medicine. It kills everything that moves fast, which includes cancer cells and hair cells. Sometimes it's just a question of application. My first treatment, 75 percent of my hair fell out. I said, no more of this and found a place that could administer the treatment without hair loss."

"Also," continued Vann, "after a lumpectomy, doctors routinely recommend chemo. They use nice but vague phrases like `significant improvement.' Basically, 75 out of 100 women who have lumpectomies test negative for further malignancy. Chemo raises that number to 83, with the other 17 women likely to have recurring cancer whether they're take chemo or not. The extra eight sounds `significant,' but what's really happening is that all 100 women are suffering through post-surgery chemotherapy for the sake of eight women who might ultimately be helped by it."

Vann began working on Top of the Bottom Half in May 1995. She auditioned co-writers and clicked with Griffith. Vann recorded 20 hours of material and then began whittling down to the hour-plus the show currently takes. "I promised myself I would not do a show about breast cancer, not fall into the trap of self-indulgence. It's part of the show, but not all of it. "

Vann, 38, looks great, has a full head of hair, and is displaying both breasts in advertisements in Time Out and The Village Voice (New York Magazine refused the ad). She considers herself cured. "I was diagnosed at 35 -- the age group that dies. Well, I went through three operations on the same tumor, but I took it step by step. I separated every procedure. It's not the end of the world, it's a disease, so deal with it scientifically. Getting through cancer is 99 percent about paying attention."

For tickets ($20-$22.50) and information on The Top of the Bottom Half call (212) 935-5820.

-- By David Lefkowitz