Sarah Ferguson, who was married to Prince Andrew and had daughters Beatrice and Eugenie with him, has made the remarks after Kate revealed her diagnosis in a video message to the nation on Friday.

The Macmillan Cancer Support charity has since revealed traffic to its online information and support pages were the highest seen on a weekend since the first COVID-19 lockdown.

The Duchess of York, who revealed in January she had been diagnosed with skin cancer, has posted on social media: "All my thoughts and prayers are with the Princess of Wales as she starts her treatment.

"I know she will be surrounded by the love of her family and everyone is praying for the best outcome.

"As someone who has faced their own battles with cancer in recent months, I am full of admiration for the way she has spoken publicly about her diagnosis and know it will do a tremendous amount of good to raise awareness."

Kate revealed in her video statement on Friday that she is undergoing preventative chemotherapy.

The Princess of Wales said she and Prince William had been doing everything they could to "process and manage this privately for the sake of our young family".

She added it has "taken time" to explain her diagnosis to her children George, Charlotte and Louis in a way that is "appropriate for them, and to reassure them that I am going to be OK".

Her statement followed weeks of global social media speculation and conspiracy theories about her whereabouts after she had not been seen on official engagements since last December.

The 42-year-old had planned abdominal surgery in January but was then not seen again publicly again until early March when she was photographed by celebrity news site TMZ.

Kate revealed in her statement to the nation that at the time of her abdominal surgery it was thought her condition was non-cancerous.

"The surgery was successful. However, tests after the operation found cancer had been present. My medical team therefore advised that I should undergo a course of preventative chemotherapy and I am now in the early stages of that treatment," she said.

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The princess also thanked the public for all "the wonderful messages of support and for your understanding whilst I have been recovering from surgery", adding it has been an "incredibly tough couple of months for our entire family".

In February, the Duchess of York urged people not to skip their health check-ups after she was diagnosed with two-types of cancer in a six-month period.

Her skin cancer diagnosis came months after she was told she had an early form of breast cancer.

The 64-year-old spoke about the importance of check-ups to mark Cancer Prevention Action Week, warning "days could make the difference between life and death".