Kate Middleton, Britain's Princess of Wales, Monday informed about finishing her course of preventive chemotherapy to treat cancer, expressing her gratitude for "simply loving and being loved".

Kate, 42, wife of heir-to-the-throne Prince William, underwent major abdominal surgery in January which revealed her cancer, and since then she has been undergoing treatment.

In a personal message accompanying a unique video of her with her husband and their three young children, Princes George and Louis and Princess Charlotte, Kate said she would be carrying out a handful of public engagements later this year, but said her path to full recovery would be long.

"As the summer comes to an end, I cannot tell you what a relief it is to have finally completed my chemotherapy treatment. The last nine months have been incredibly tough for us as a family. Life as you know it can change in an instant and we have had to find a way to navigate the stormy waters and road unknown," Kate said.

Kate said she is looking forward to being back at work and undertaking a few more public engagements in the coming months.

"William and I are so grateful for the support we have received and have drawn great strength from all those who are helping us at this time. Everyone’s kindness, empathy and compassion has been truly humbling," she said.

Kate made her first public appearance since her health issues emerged in June at the annual military parade to mark the official birthday of King Charles. In July, she appeared at the Wimbledon tennis championships.