The 50-year-old star had previously battled cancer and even lost a past boyfriend to bowel cancer.
Caroline’s brother, Patrick, told The Mirror: ‘The form of lung cancer that she is suffering from is genetic and linked to the retinoblastoma she had as a baby.’
‘Her bladder cancer was also genetic and linked to her retinoblastoma.’
Caroline is a campaigner for cancer charity Macmillan and recently spoke at a launch for the charity’s new fundraising drive.
She said: ‘I’ve had cancer and my brother has had cancer – we know how it affects people.’
‘Macmillan have asked me to get involved and I’m really glad that I can do my bit to encourage Manchester people to speak up about where things do go wrong with cancer care.’
Following her diagnosis, Caroline revealed that she still plans to keep her role as narrator of hit TV show Gogglebox.
She said: ‘I will be narrating this week’s Gogglebox and will continue to narrate Gogglebox for as long as Gogglebox want me.’
Caroline shot to fame as Denise Best in classic sitcom Royle Family and is also known for her famous Mrs Merton character.