Britain's Catherine, Princess of Wales reacts upon arrival during a visit to the Royal Marsden Hospital in west London on January 14, 2025. Chris Jackson, AFP

LONDON, United Kingdom -- Catherine, Princess of Wales, said on Tuesday she was "in remission" from cancer after she and husband Prince William visited the specialist London hospital where she was treated.

"It is a relief to now be in remission and I remain focused on recovery," the princess posted on Instagram, alongside a picture of her visit to the Royal Marsden Hospital.

The couple thanked staff and met patients at the specialist cancer center operating across three sites in the capital.

READ: Catherine, Princess of Wales says she has completed chemotherapy

"I wanted to take the opportunity to say thank you to The Royal Marsden for looking after me so well during the past year," Catherine wrote on Instagram.

"My heartfelt thanks goes to all those who have quietly walked alongside William and me as we have navigated everything.

"We couldn't have asked for more. The care and advice we have received throughout my time as a patient has been exceptional," she added.

The visit came as Kensington Palace announced that the couple had become the hospital's joint patrons.

As patrons, members of the royal family support over 3,000 organizations such as charities and hospitals by highlighting their work through visits.

"In my new role as joint patron of The Royal Marsden, my hope is that by supporting groundbreaking research and clinical excellence, as well as promoting patient and family wellbeing, we might save many more lives, and transform the experience of all those impacted by cancer," said the princess.

The visit was said to be "incredibly poignant" for the princess, also known as Kate, who turned 43 last week.

The future queen, seen as key to maintaining the royals' position in a changing Britain, revealed last March she had been diagnosed with an unspecified cancer and was undergoing chemotherapy.

© Agence France-Presse