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Sarah Ferguson Duchess of York Diagnosed with Breast Cancer, Undergoes Surgery

Sarah Ferguson, Duchess of York, went into surgery after learning she had an early form of breast cancer.

The Duchess, the ex-wife to Prince Andrew, went under the knife after a routine mammogram revealed her diagnosis. She was released from the hospital Sunday and is receiving ongoing medical care while recovering with her family. She still lives with Andrew.

Sarah's doctors told her the prognosis is good. The surgery was described as successful, thanks to the early catch. A friend told The Sun Sarah's extremely thankful for the medical staff.

She was missing from last week's Royal Ascot event at the Ascot Racecourse, and now we know why. Sarah took to social media Monday ... thanking everyone for their support.

Sarah -- or "Fergie" -- was once married to King Charles' brother, Andrew ... but they divorced in 1996 after a decade of marriage.

She did, however, keep the title of Duchess after the split.

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