'We have climbed many mountains together.' Family responds to Kate Middleton's news.

Kate Middleton's family has responded to the news that the Princess of Wales has been diagnosed with cancer.

Princess Kate, 42, revealed the news via a moving video message, thanking the public for their well wishes. As the world grapples with the news, her loved ones have begun publicly expressing their love and support.

Princess Kate's younger brother, James Middleton, shared a never-before-seen image of the pair as children, along with a touching message for his big sister. 

"Over the years, we have climbed many mountains together," he wrote. 

"As a family, we will climb this one with you too."

View this post on Instagram

A post shared by James Middleton (@jmidy)

Meghan Markle and Prince Harry have also released a statement.

"We wish health and healing for Kate and the family, and hope they are able to do so privately and in peace," the Duke and Duchess of Sussex said.

It comes following Princess Kate's announcement that she had undergone major abdominal surgery, and has commenced preventative chemotherapy treatment, after her medical team discovered cancer had been present. 

"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," she said in the announcement video.

Her office, Kensington Palace, said it would give no further details about the type of cancer.

King Charles shared in February that he too was to have treatment for cancer, meaning he has had to postpone his public royal duties.

More to come.

Feature Image: Instagram/@jmidy.