Revealing her diagnosis in an emotional video message, the Princess said: “I am well and getting stronger every day.”

She added: “In January, I underwent major abdominal surgery in London and at the time, it was thought that my 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.

“This of course came as a huge shock, and William and I have been doing everything we can to process and manage this privately for the sake of our young family. As you can imagine, this has taken time.”

The Princess was admitted to the London Clinic in January for abdominal surgery.

Since the surgery, the 42-year-old Princess has been largely absent from the public eye, leading to speculation about her health which the Archbishop of Canterbury described as “village gossip” and “wrong”.

Reports also emerged of an alleged attempt to access the Princess’ medical records while she was at The London Clinic.

Responding to the claims, the clinic vowed that all appropriate steps will be taken when dealing with the alleged data breach.

CEO Al Russell said: “Everyone at the London Clinic is acutely aware of our individual, professional, ethical and legal duties with regards to patient confidentiality.

"We take enormous pride in the outstanding care and discretion we aim to deliver for all our patients that put their trust in us every day.

"We have systems in place to monitor management of patient information and, in the case of any breach, all appropriate investigatory, regulatory and disciplinary steps will be taken.

"There is no place at our hospital for those who intentionally breach the trust of any of our patients or colleagues."

King Charles diagnosed with cancer

The news comes after King Charles was diagnosed with cancer in February.

A statement from Buckingham Palace at the time confirmed: “During the King’s recent hospital procedure for benign prostate enlargement, a separate issue of concern was noted. Subsequent diagnostic tests have identified a form of cancer.

Buckingham Palace announced King Charles had been diagnosed with cancer in February (Image: Joe Giddens/PA Wire)

“His Majesty has today commenced a schedule of regular treatments, during which time he has been advised by doctors to postpone public-facing duties. Throughout this period, His Majesty will continue to undertake State business and official paperwork as usual."

The Palace added that the Princess' father-in-law was "wholly positive about his treatment and looks forward to returning to public duty".

The statement continued: “His Majesty has chosen to share his diagnosis to prevent speculation and in the hope it may assist public understanding for all those around the world who are affected by cancer.”