Sarah Ferguson has lifted the lid on Princess Eugenie and Princess Beatrice’s reaction to her health update. The Duchess of York was diagnosed with breast cancer during a routine mammogram last year, undergoing a single mastectomy. Then in January this year, Fergie, 64, was found to have malignant melanoma. In a new interview, the duchess gave a health update, admitting she was told by doctors to avoid the phrase “cancer-free”, and is having regular check-ups for any recurrence. However, the duchess’s outlook remains positive. Fergie said: “I have to be checked regularly and I have to put crea…