Dame Esther Rantzen has announced she is stepping down as president of Childline due to health reasons, 37 years after she founded the children's counselling service.
Earlier this year the 83-year-old TV presenter and activist announced she had been diagnosed with lung cancer.
In May she said the cancer had progressed to stage four.
Dame Esther's daughter, Rebecca Wilcox, will deputise for her, the NSPCC - which merged with Childline in 2006 - announced.
In a statement Dame Esther and her daughter said: "Because of Esther's health issues, she has sadly had to reduce her work as president, but we are both thrilled that Childline and the NSPCC have suggested that her daughter Rebecca should now deputise for her.
"She feels deeply honoured to take on this role, she has grown up with Childline and enormously values the many achievements of the service, the dedicated staff and volunteers, all working to protect and support millions of children who have nowhere else to turn."
Their statement added: "Rebecca has two sons, is a journalist and broadcaster and is very in touch with the challenges facing young people today.
"Rebecca is about to start training as a volunteer counsellor and is greatly looking forward to meeting as many volunteers and staff and visiting as many bases as possible. "
In January Dame Esther said her cancer had "spread" but she was "remaining optimistic".
However, in May she said her cancer had progressed to stage four - which Cancer Research UK says is when the cancer has spread from where it started to another body organ and is also called secondary or metastatic cancer.
Diagnosis 'made me realise how very lucky I've been'
"My diagnosis of stage four lung cancer made me realise how very lucky I've been in my life, working with Childline and the Silver Line, and meeting so many fascinating and inspiring people, and especially lucky to have spent 21 years working as producer/presenter of That's Life!" she told The Mirror at the time.
"I'm not good at regrets," she added.
"What I treasure most are the fantastic friendships I have made thanks to That's Life! during the last 50 years, the people I met and the team who worked so hard, and laughed so hard, together for so long."
In 1986 Dame Esther set up Childline - which offers counselling and support for children and young people in the UK up until the age of 19 - and led a successful career as a journalist and broadcaster.
She also set up The Silver Line in 2013, a charity which supports elderly people in the UK who are battling loneliness.
She was made a DBE in 2015 for services to children and older people and received the Lifetime Achievement Award at the Women of the Year Awards for her philanthropy in 2021.