Kate's cancer diagnosis updates: Reactions from around the world
World leaders and the royal family are offering support to Catherine she reveals she is undergoing cancer treatment, the BBC reports.
The Princess of Wales put out a video statement, recorded by the BBC, saying she is in the early stages of treatment after cancer was found in tests.
Following weeks of speculation over her health, Kate asked the public for "time, space and privacy" while she completes her treatment.
Separately to her statement, Kensington Palace said the princess began a course of preventative chemotherapy in late February. But the palace did not disclose details of the cancer, adding that Kate "has a right to medical privacy, as we all do".
Her brother-in-law, Prince Harry, and his wife, Meghan, said: "We wish health and healing for Kate and the family, and hope they are able to do so privately and in peace."
King Charles said he is "so proud" of his "beloved" daughter-in-law's courage. The King, who is himself being treated for cancer, said himself and Queen Camilla would "continue to offer their love and support to the whole family through this difficult time".
New Zealand Prime Minister Christopher Luxon, on X, said: "New Zealand's thoughts are this morning with the Princess of Wales following the news of her cancer diagnosis. I know Kiwis across the world will be wishing her well in her recovery".
The princess's statement explained that when she had abdominal surgery in January, it was not known that there was any cancer.
Look back at the developments with RNZ's blog: