The award winning TV writer and actress, who is undergoing treatment for lung cancer related to a genetic form of the disease, joked about it being the third time she has faced the disease.
Aherne said: "My brother and I were born with cancer of the eyes, the retina, my mum told us only special people get cancer. I must be very special because I have had it in my lungs and bladder as well."
The comedian gave a typically irreverent speech about her treatment and condition as she spoke to a gathering of 170 cancer patients, medics and carers at Manchester Town Hall for the launch of a new scheme to improve cancer care in the city.
She described her own Macmillan cancer nurse, Julie Watts, as "like an angel,"
She said: "When you hear them telling you you have cancer, it's true that you really don't take it in properly, you just don't think of the questions and then when you come out because she's been in there with you she answers all your questions that you haven't been able to ask at the time or haven't thought of.
"This is the best bit that they understand they completely understand what you are going through and what your family are going through."
Aherne shared a joke from the time of her chemotherapy treatment at the Cecilia Centre at Wythenshawe Hospital, involving Royle Family co-star Ricky Tomlinson who played her on-screen father.
Aherne said: "The cleaner came in one day, she went, 'Oh, I knew you were here, they told me you were here, oh that's great, I love the Royle Family but I would've much preferred it to be Ricky in that bed!'
"She was wishing lung cancer on Ricky Tomlinson!"
Aherne continued: "I don't know why this popped into my head, but you know when you are in intensive care and they wash you, this nurse said, 'Do you want to wash your own fairy?
"So, er, I'm now my own fairy washer!"
She added: "I just hold my hands up and say, 'thank God for Macmillan nurses'. Fifty years ago when my mum found out that we had cancer they didn't have any Macmillan nurses you were kind of on your own with it so it's a blessing we have got them now."
At the end of her speech Aherne smiled, put her hands to her hair and joked: "My wig stayed on!"
The 50-year-old, whose comedy creations have also included her spoof chat host Mrs Merton, revealed last month she was battling lung disease after agreeing to help launch the new initiative in her home town Manchester.
Research by cancer charity Macmillan showed the city came bottom out of 150 areas in England for premature deaths from cancer.
The city is also bottom of the league table for strokes, heart and lung disease.
Survival rates are 25% lower than average and the number of people getting lung cancer is a third higher in the city than in the rest of England.
The new £3.4 million scheme, called the Macmillan Cancer Improvement Partnership (MCIP) aims to bring together all cancer care providers in the city to improve the experience of everybody affected by the disease.
Aherne added: "We can't allow Manchester to continue to be the worst place in England for premature deaths from cancer - not to mention all the other appalling statistics we've been hearing.
"That's why the Macmillan Cancer Improvement Partnership's been formed. Everyone in this room wants to make it better - and it's why I'm supporting MCIP and asking other people in Manchester who are affected by cancer to get involved.
"Information posters - and what they're calling pledge cards are being sent out to all of Manchester's GP surgeries, hospitals, Macmillan information centres and city council public places.
"I'm asking people who've been affected by cancer in any way - and want to make a difference to care to fill one of these pledge cards out - and send it back to the freepost address.
"They might just want to make a comment. They might want to sit down with doctors and nurses and give ideas. They might want to get involved in workshops to develop new services.
"Whatever it is - the involvement of patients, carers and families needs to lie at the heart of this hugely ambitious re-design of cancer services.
"We've all got a chance here to make a difference - and none of us should pass that up."
Ciaran Devane, chief executive, Macmillan Cancer Support said: "We are hugely grateful to Caroline Aherne for supporting Macmillan and MCIP and helping us recruit people affected by cancer, particularly at a time when she is undergoing cancer treatment herself in Manchester.
"It was generous-spirited of her to sacrifice her privacy at a difficult time to help make things better for others in Manchester who are being and will be treated for cancer in Manchester."
Aherne can currently be heard as the voice of hit Channel 4 show Gogglebox and has said she would continue working on the show.
Aherne, who has been a smoker, has struggled with health problems for years.
She has fought depression and drink problems and spent time in the Priory clinic following a suicide attempt, before moving to Australia to avoid the glare of publicity.
The star has also had a string of failed relationships - her marriage to former New Order guitarist Peter Hook ended and she began a romance with TV researcher Matt Bowers.
They split but she was devastated when he died of cancer at the age of 28.
Her much-loved programme The Royle Family ran for three series and has returned for a number of seasonal specials, most recently at Christmas 2012.