London — Catherine, the Princess of Wales, announced in a video message released Friday that cancer was discovered during her January abdominal surgery and she is undergoing preventative chemotherapy on the advice of her medical team. The announcement came after months of widespread speculation about the 42-year-old princess’ health and controversy over doctored images released by Kensington Palace.

Kate said that the cancer was discovered during tests conducted after her surgery, which had gone well.

“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 said in the video message. “As you can imagine, this has taken time. It has taken me time to recover from major surgery in order to start my treatment. 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.”

Kensington Palace said the video message was filmed by BBC Studios in Windsor on Wednesday. In it, Kate said she was in the “early stages” of her chemotherapy treatment.

“I am well and getting stronger every day by focusing on the things that will help me heal; in my mind, body and spirits,” Kate said in the video. “Having William by my side is a great source of comfort and reassurance too. As is the love, support and kindness that has been shown by so many of you. It means so much to us both.”

She said that she would continue to take the time and space she needs to undergo treatment and recover, and asked the public for understanding.

“My work has always brought me a deep sense of joy and I look forward to being back when I am able, but for now I must focus on making a full recovery. At this time, I am also thinking of all those whose lives have been affected by cancer. For everyone facing this disease, in whatever form, please do not lose faith or hope. You are not alone.”

Kate’s announcement comes after growing public speculation over her health that until now had been met with silence from the palace.

In January, Kensington Palace announced she underwent planned abdominal surgery and would be taking time to recover in private at least until Easter, on March 31. It said there would be no updates on her health as she recuperated, and said the surgery was not cancer-related.

Then on Britain’s Mother’s Day in March, Kate and her husband, the Prince of Wales, released an image of Kate and her three children that had clearly been doctored, fueling ongoing speculation about her health. Several leading global photo agencies recalled the image.

Kate admitted in a social media post to editing the image, but Kensington Palace refused to release an original, unedited version. Another photo that had been released of the late Queen Elizabeth with her grandchildren also appeared to have been altered.

British tabloids reported Sunday that Kate was spotted in public, publishing a grainy video appearing to show her and William at a farm shop near her family’s home in Windsor. The tabloid quoted onlookers as saying she appeared “happy, relaxed and healthy.”

In February, Kate’s father-in-law, King Charles, announced that he would be undergoing treatment for an unspecified form of cancer which was discovered as he was being treated for an enlarged prostate. Charles and his wife, Queen Camilla, have issued updates about his well being, thanking the public for their support.

Haley Ott

Haley Ott is the CBS News Digital international reporter, based in the CBS News London bureau.