Sarah Ferguson had no symptoms before her shock breast cancer diagnosis, it has been confirmed.
The Duchess of York, 63, has undergone an operation at King Edward VII hospital in Marylebone, Central London, which has been described as "successful".
She is now recovering at home with her family in Windsor, Berkshire.
The grandmother of three spent several days in the London hospital this week after being told she had an early form of the disease during a routine mammogram.
A representative confirmed she had no symptoms ahead of her shock diagnosis.
They said: “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.
"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."
Fergie, who missed Royal Ascot this week due to her operation, is said to be at Royal Lodge recuperating with her family, including Prince Andrew, 63, and daughter Beatrice, 34, and Eugenie, 33.
One friend told The Sun the "prognosis is good" because of the "early detection".
The source said: "It's been a difficult time but she is very grateful to the medical staff who carried out the mammogram and detected it early and the medical staff who looked after her these last few days, she is incredibly thankful."
Sarah is a patron for Teenage Cancer Trust and spoke at a Breast Cancer Foundation gala in 2019.
In 2021, Sarah visited a clinic in Poland to address the issue of women recovering after receiving a mastectomy.
Beatrice was spotted with friends at Glastonbury on Sunday, the final day of the festival, and was at Royal Ascot earlier this week.
The duchess is expected to discuss her diagnosis in her new podcast, Tea Talk, which was pre recorded.
