Kate, Princess of Wales, has revealed she has been diagnosed with cancer and is undergoing preventative chemotherapy.
In a personal message, the 42-year-old said planned abdominal surgery in January was successful and it was initially thought her condition was non-cancerous.
But tests after the operation found cancer had been present, she said, adding: “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.”
Kate cancer latest: Princess of Wales releases statement after diagnosis
Watch Princess of Wales’s video message in full
The mother of George, Charlotte and Louis said doctors had advised her to have a course of preventative chemotherapy and she is currently in the early stages of that treatment.
“It has taken me time to recover from major surgery in order to start my treatment,” she said.
“But, most importantly, it has taken us time to explain everything to George, Charlotte and Louis in a way that is appropriate for them, and to reassure them that I am going to be ok.
“As I have said to them; I am well and getting stronger every day by focusing on the things that will help me heal; in my mind, body and spirits.”
She described having her husband Prince William by her side as a “great source of comfort and reassurance”, adding: “As is the love, support and kindness that has been shown by so many of you – it means much to us both.”
The princess’s chemotherapy began in late February, although it is unclear when it will end.
Kensington Palace said it would not be sharing the type of cancer, adding: “The princess has a right to medical privacy, as we all do.”
It is also unclear when the princess will return to official duties – the palace said she would do this “when she is cleared to do so by her medical team”.
Prince William, meanwhile, will “continue to balance supporting his wife and family and maintaining his official duties, as he has done since the start of the year”, the palace said.
Kate has not been seen on official engagements since late December, when she was pictured on a Christmas Day walk with other members of the Royal Family in Sandringham, Norfolk.
The future queen’s long absence had sparked global social media speculation and conspiracy theories, and a Mother’s Day photo released of her and her three children did little to quell the frenzy after it was revealed to have been edited.
Earlier this week, The Sun published a video of the couple on a visit to a farm shop in Windsor, with an onlooker describing the princess as “super happy” and “relaxed”.
Confirmation of Kate’s illness comes less than two months after King Charles, 75, announced he had been diagnosed with cancer.
His cancer came after hospital treatment for an enlarged prostate, although it is not known what type of cancer he has or what stage it is at.