BY CORKY SIEMASZKO
DAILY NEWS STAFF WRITER

Wednesday, August 1st 2007, 11:45 AM

Most common cancer among women, other than skin cancer. Second-leading cause of cancer death in women, after lung cancer.

Almost 241,000 women in the U.S. will be diagnosed with breast cancer this year, and 40,460 women will die from it.

Risk factors:

Age: Nearly eight out of 10 breast cancers are found in women age 50 or older.

Genetics: About 5% to 10% of breast cancers are linked to gene mutations.

Family history: Having a mother, sister or daughter with breast cancer about doubles a woman's risk.

Race: White women are slightly more likely to get breast cancer than are African-American women. But black women are more likely to die of it.

Detection:

Women age 40 and older should have a mammogram every year. Women at high risk might start younger and get extra or more frequent screens.

Famous women who have been treated for breast cancer:

Elizabeth Edwards, actress Edie Falco, singers Melissa Etheridge, Sheryl Crow and Olivia Newton-John, activist Gloria Steinem, former Supreme Court Justice Sandra Day O'Connor

Popular "Good Morning America" co-host Robin Roberts will undergo surgery Friday after stunning her fans with these words: "I have breast cancer."

"I'm very blessed and thankful that I found it early and detected it," Roberts added yesterday on the ABC morning show. "Still, hearing the words and saying it and seeing - it's surreal."

Roberts, 46, said she felt something suspicious in her breast after preparing a tribute to Joel Siegel, the "GMA" film critic who died last month of colon cancer.

"That very night, I found a lump," Roberts told co-host Diane Sawyer, a slight catch in her voice. "Normally, I would have not done anything because I'm healthy, right?

"[But] Joel was resonating in my heart, so I called the doctor and made an appointment."

Roberts' sister, Dorothy McEwen, told The News Roberts told the family she had cancer on July 16, after a family reunion on Mississippi's Gulf Coast. McEwen said she and her mother will be at Roberts' hospital bedside after the operation.

"It was shocking initially, and I was in complete denial because we don't have a family history of breast cancer," McEwen said. "I think she's very courageous for sharing her story."

On the ABC Web site, Roberts wrote that her cancer was caught "in the early stages and the prognosis is so promising that my doctor expects me to be flying planes and hanging on to submarines in the middle of the Atlantic and scaling the Mayan Pyramids in no time."

JoAn Nicely, a friend of Roberts and a breast cancer survivor who founded the Pink Heart Fund, a nonprofit organization in south Mississippi that helps survivors buy wigs and prostheses, said the stricken newswoman "has a great attitude."

"She seems to have been diagnosed with the kind of cancer that I had, which was ductal carcinoma in situ or DCIS," Nicely said. "That means the cancer is isolated."

Roberts could not be reached to confirm that, and ABC spokesman Jeffrey Schneider declined to discuss her condition in detail.

News of Roberts' illness struck many of her ABC colleagues hard, sources said. In recent years, ABC also weathered the death of longtime anchor Peter Jennings from cancer and nearly lost another anchor, Bob Woodruff, after he was badly wounded in Iraq.

"Every time something like this happens, it just brings all of us closer together," Schneider said. "We all adore Robin Roberts....We all feel lucky this was caught early and her prognosis is so excellent."

Roberts made it clear she intends to continue working but warned Web site readers, "I will have my good days and my bad days." On the bad days, "GMA" regulars Sam Champion, Chris Cuomo and Kate Snow will fill in, Schneider said.

Dr. Julia Smith, who heads the NYU Cancer Institute's Breast Cancer Screening and Prevention Program, said Roberts did a great service for other African-American women by going public.

"Studies have found that African-American women have a higher death rate from breast cancer," Smith said. "Robin Roberts' experience really points to the enormous benefits of being aware of the danger and being screened."

csiemaszko@nydailynews.com