Sarah Ferguson endured an eight-hour breast cancer operation, it has been reported.
Last week it was revealed that the Duchess of York had been diagnosed with the disease.
She underwent a successful single mastectomy at King Edward VII's Hospital in London.
The grandmother of three spent several days in the hospital last week and previously told of her "immense gratitude" to the medical staff.
A spokesman for the Duchess told the Mirror: "Sarah, Duchess of York was recently diagnosed with an early form of breast cancer detected at a routine mammogram screening.
"She was advised she needed to undergo surgery which has taken place successfully."
It was previously reported that the 63-year-old learned she had the disease after going for a routine mammogram.
A friend of the duchess has since told the Mail on Sunday that the surgery lasted eight hours and spent four days in intensive care, adding that she feels "lucky to be alive."
They said: "The surgery was very long – getting on for eight hours – and it was more involved than people think. Today, the message she wants to get out is that she is very grateful to those who saved her and she feels very lucky to be alive.
"Specifically, the duchess wants to thank the two incredible surgeons Christina Choy and Stuart James who carried out the operation and all the medical team who worked tirelessly to help her."
This week we reported how the duchess has vowed to urge a national breast cancer screening drive.
A source close to her told the Mirror she is recovering well and had pledged to use her experience to help women of 50 to 70 see the importance of getting checked regularly.
A pal said: “Undoubtedly this will be an issue the duchess takes up as she feels it is incredibly important to spread this message and awareness.”
The Duchess of York's representatives previously told Mirror the royal says her experience "underlines the importance of regular screening".
Speaking to the Mirror last week, her representative said: "The Duchess is receiving the best medical care and her doctors have told her that the prognosis is good. She is now recuperating with her family.
"The Duchess wants to express her immense gratitude to all the medical staff who have supported her in recent days.
"She is also hugely thankful to the staff involved in the mammogram which identified her illness, which was otherwise symptom-free, and believes her experience underlines the importance of regular screening."
A mammogram is a breast X-ray which looks for signs of cancer too small to see or feel. Women aged between 50 and 71 are automatically invited for breast screening every three years.
