Catherine, Princess of Wales, is being treated for an undisclosed form of cancer, she revealed Friday.

In a video statement, the 42-year-old princess thanked the public for their support during this time.

The princess said that she underwent "major abdominal surgery" in January and, at that time, her condition was thought to be "non-cancerous."

Catherine said she is in the "early stages" of a preventative course of chemotherapy. She did not identify the specific type of cancer she is facing.

Catherine's father-in-law, King Charles, is also being treated for cancer. The 75-year-old king has suspended his public duties while undergoing treatment.

WATCH | Kate's statement on her cancer diagnosis: 

Princess of Wales says she's receiving cancer treatment

Catherine, the Princess of Wales, says in a video released to her social media pages that tests after her surgery revealed 'cancer had been present,' and that she is in the early stages of preventive chemotherapy.

The princess said the news of her own cancer had been "a huge shock" for herself and her family.

Kensington Palace said the update on her health was shared at a time when Catherine and William's children were on break from school, to shield them from related news coverage.

Speculation about Catherine's health had reached a fever pitch in recent weeks. Friday's disclosure provides more context on the challenges she has been facing.

Catherine married Prince William in 2011. They have three children — George, 10, Charlotte, 8, and five-year-old Louis.

More to come.