U.S. & World

CHAPEL HILL, N.C. (CBS News) ― Once breast cancer returns to spread beyond the breast, it's no longer curable — but it can be held in check, sometimes for years, depending on how aggressive the tumor proves to be.

The average survival rate has been 2 1/2 to five years, CBS News medical correspondent Dr. Jon LaPook reports. But doctors say the odds are improving, thanks to newer therapies that target the cancer with fewer side effects.

Doctors don't yet know exactly how widespread Elizabeth Edwards' returned cancer is, beyond a small but definite spot found in her right rib after she coincidentally broke a rib on the other side. Also being checked out is a suspicious spot in her lung.

"We can suppress it, we can even shrink it, but we can't eradicate it," said Dr. Lisa Carey, Edwards' oncologist.

But the key question when breast cancer turns metastatic — the doctor's ominous term for spreading cancer — is whether it is hormone-sensitive.

John Edwards revealed the closely guarded prognosis — even family friends and some senior campaign staff were unaware — at a news conference Thursday, his wife by his side in the hotel garden where they held their wedding reception 30 years ago.

Putting to rest speculation about his political future, Edwards told reporters: "The campaign goes on. The campaign goes on strongly."

The recurrence of the cancer — this time on Elizabeth Edwards' bone — presents a setback for the couple, both personally and politically. Elizabeth Edwards' illness and treatment is certain to affect her husband's presence in the early voting states and may raise questions about the viability of his campaign, especially with financial backers. The first fundraising deadline is fast approaching on March 31.

Her health problems already have impacted the campaign. Edwards had canceled a Tuesday evening house party in Iowa to go with his wife to a doctor's appointment.

No matter where breast cancer turns up in the body, if its growth is fueled by estrogen, women have a better chance of longer survival — and a shot at controlling the cancer with a battery of anti-estrogen drugs instead of needing harsher chemotherapy, at least right away.

Carey didn't reveal whether Edwards' cancer is this better "estrogen receptor-positive" form, saying that she was awaiting further test results before deciding on a treatment.

"It's hopefully and very likely treatable," said Dr. Julia Smith, head of the New York University Cancer Institutes' breast cancer prevention program. But, "it will limit her life ... The goal now is to give the least amount of therapy and least toxic therapy, and drag it out for as long as possible, so she can have the best quality of life as long as possible."

Almost 213,000 U.S. women will be diagnosed with breast cancer this year, and almost 41,000 will die, according to the American Cancer Society. When caught early, the vast majority survive with a combination of surgery, chemotherapy and radiation, just as Edwards had in November 2004.

But about 20 percent of women thought to have been treated successfully at first nonetheless see their cancer return. How soon that happens, where it happens and how soon it's caught helps determines their prognosis.

There are few good estimates of survival time for these patients. But treatment is easiest if the recurrence is limited to the breast or surrounding lymph nodes. Survival is much shorter if the cancer spreads aggressively to vital organs like the liver, lungs or brain.

The bone seems to be somewhere in the middle. Indeed, a subset of patients with estrogen receptor-positive tumors that appear in only the bone have a good chance at surviving for 10 years, said NYU's Smith. "Unfortunately, we don't know who that group is in advance," she said.

Edwards' oncologist offered no survival predictions, either.

"I don't have a crystal ball about how she is going to do. I can tell you that many patients with exactly the circumstances that she has, do very well for a number of years," Carey said. "And the fact that she is a healthy person, and that there isn't a lot of the cancer, and that she doesn't have symptoms, all work in her favor."

Edwards' recurrence happened fairly early, just over two years after her initial diagnosis. But she said she blessed the broken rib that warranted the X-ray this week that in turn uncovered the cancer lurking nearby.

"I'm very lucky I cracked this rib," she said.

(© 2007 CBS Broadcasting Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)