Prince William has been a “great source” of support to Kate Middleton during her cancer diagnosis and chemotherapy treatment, the princess said Friday.

The Princess of Wales revealed her cancer diagnosis earlier this year came as a “great shock” to her and her husband, but he has been supportive throughout her health journey.

“Having William by my side is a great source of comfort and reassurance too,” she said while sharing her diagnosis in a video on Friday.

The princess has not revealed what type of cancer she is battling.

Kate learned of her diagnosis after undergoing “major abdominal surgery” back in January at the London Clinic.

“The surgery was successful. However, tests after the operation found cancer had been present,” she said.

“My medical team therefore advised that I should undergo a course of preventative chemotherapy and I am now in the early stages of that treatment.”