NSW Labor deputy leader Prue Car has spoken about the heartbreaking moment she had to tell her son, Max she had cancer.

The Shadow Education Minister, who is now facing another battle to retain the seat of Londonderry that she has held since 2015, was diagnosed with cancer in July last year.

She told Deborah Knight that she thought she was just tired until her husband, a nurse, urged her to go to the doctor.

“I was very upset, my little boy is only nine, that is all you can think about,” she said.

“It is a hard conversation with a nine-year-old.

“He kept saying: “What do you mean?”

“Kids are amazingly resilient, but you do worry.”