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Elizabeth Edwards, wife of presidential candidate John Edwards, has had a recurrence of cancer and it has spread from her breast to a rib bone, her husband announced Thursday.

He said the bone cancer can not be cured, it can only be treated.

"The biopsy showed the cancer had returned, it was malignant. Later in the day we did a CT scan ... the CT scan showed very little. So the net result of all the tests is that her cancer is back, it is largely confined in bone, which is a good thing," the candidate said from their hometown of Chapel Hill, N.C.

Despite the news, Edwards is making no plans to suspend his 2008 presidential bid. He and his wife attended a campaign-related barbecue in their hometown of Chapel Hill, N.C., on Wednesday night. The couple is going together to California, Boston and New York for events scheduled through the weekend.

"The campaign goes on, the campaign goes on strongly," Edwards said.

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"It's important that the American people have the opportunity to have a president like him and I cannot deprive him of that because I want to sit home perfectly well but wanting his company," a smiling Elizabeth Edwards, 57, said.

"I expect to do next week all the things I did last week," she added, acknowledging that the medication she will be prescribed could add to her fatigue. She noted, however, that her 6- and 8-year-old children probably will tire her more than the medicine.

The Edwardses explained that the new cancer had been diagnosed after Elizabeth felt a pain in her left side and decided to get an X-ray. Doctors discovered that she had fractured a left rib, but "something that looks suspicious" had been found in a rib on her right side.

The former North Carolina senator abruptly canceled a campaign event in Iowa on Wednesday to accompany his wife to a follow-up visit after a Monday appointment

Rumors had been flying all Thursday morning that Elizabeth's health had taken a turn for the worse and Edwards was going to stop his campaign. But staff had warned off many reporters from making any announcement that he was abandoning his race.

Fundraiser Lee Hamilton, an attorney from Montgomery, Ala., said the Edwardses had been tight-lipped about their plans in a morning news conference with staff.

"As far as we're concerned, this is just another day to raise money," Hamilton said before the announcement.

Elizabeth first announced she had been diagnosed with breast cancer right after the 2004 presidential race. Edwards was the Democratic vice presidential candidate running alongside Sen. John Kerry after faring well in the primary race.

When Edwards announced his decision to run for the White House in late December 2006, he said it was based on the fact that his wife had gotten a clean bill of health from doctors. He repeated Thursday that if the time comes when his wife needs him to tend to her, he will leave the campaign.

But Edwards said that since his wife appears to be doing fine, he decided to continue with his plans. She added that she wanted to hold a press conference rather than issue a press release so that people could see how robust she is.

"Well, anyone who wants to be president of the United States needs to understand and recognize that there will be very difficult, intense, high pressure times when judgments have to be made. And if you're not able to, in a focused, thoughtful way, deal with this kind of pressure, you are not ready to be president," he said.

Elizabeth had surgery in early 2005 after being diagnosed with invasive ductal cancer, the most common type of breast cancer. It can spread from the milk ducts to other parts of the breast and beyond.

After the surgery, she underwent a series of radiation and chemotherapy treatments. Since then she has closely monitored her health and had several doctors visits, all with positive outcomes until now.

Robert Ashton, a doctor at Hackensack University Medical Center, told FOX News that advances in medical care means a cancer diagnosis is no longer a death sentence.

"When it spreads people live a very normal life under treatment for many years with a good quality of health," said Ashton, who is not one of the Edwards' doctors.

The Edwardses have been married nearly 30 years and had four children. Their oldest child, Wade, died in a car accident in 1996. Elizabeth described her life and ordeals in a book published last year called "Saving Graces." In several interviews, she said she could not have gone through those challenges without the support of her husband.

Edwards is running in the top tier of Democratic candidates with Sens. Hillary Clinton and Barack Obama. He led in one recent and very important poll — Iowa caucus-goers who will cast the first ballots in January.

The tough fight between Obama and Clinton also puts Edwards in the potentially strong position of sitting on the sidelines while the two senators savage each other into unelectability. Throughout his current bid and the 2004 race, Elizabeth served as her husband's closest political adviser.

Obama and his wife released their expressions of support after hearing the news.

"Today, Michelle and I join every American in sending our thoughts and prayers to Elizabeth and John and the entire Edwards family. We all admire Elizabeth’s strength and determination and the deep love they so obviously share," the Obamas said in a statement.

Elizabeth, born in Jacksonville, Fla., grew up between the United States and Japan because of her father's career as a Navy pilot. She met her future husband at University of North Carolina law school.

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FOX News' Carl Cameron and The Associated Press contributed to this report.