Linda Nolan and Bill Turnbull are among the celebrities with cancer who have joined NHS doctors in urging the public to come forward for important checks.
The call comes after concerns were raised that people have delayed seeking help due to the coronavirus pandemic.
It has been shown in the past that celebrities opening up about their cancer diagnoses has led to increases in referrals.
Nearly half of the public have said they had concerns about seeking help in the midst of the outbreak, while one in 10 said they would not contact their GP even if they had a lump or a new mole.
Both Linda and her sister Anne, who were part of Irish family pop group The Nolans, recently announced that they had been diagnosed with cancer within days of each other.
Linda, 61, has been undergoing treatment for liver cancer, while Anne, 69, has stage three breast cancer.
Another sister, Bernie, died of breast cancer in 2013 at the age of 52.
Linda, who is receiving chemotherapy at Blackpool Victoria Hospital, said: The care I have received has been nothing short of exceptional, and I know people up and down the country have had similar experiences of the heroic work the NHS and staff are doing to continue to deliver the vital care we all need, even as they deal with the ongoing pandemic.
“So, whilst it might seem daunting, it’s important people know they can feel absolutely safe in the hands of the NHS going in for treatments.”
Hospitals have put in extensive measures so patients can get safely tested and treated, and Linda added: “If there is care or a treatment you need, don’t delay, and contact your GP or NHS 111 to ask about any symptoms.
“It’s so important people get checked out when they need to. Cancer doesn’t wait, and timing is everything. It might be the very thing that makes all the difference.”
There has been a sharp drop in the number of people coming forward for cancer checks, with 141,643 referred in June compared with almost 200,000 during the same period last year.
Former BBC Breakfast star Turnbull first talked about his diagnosis in 2018, which led to a 36% jump in people being referred for prostate cancer, and it is now the most common cancer in the country.
He said: “Cancer is a cruel disease and unfortunately it did not disappear during the coronavirus outbreak.
“We know that it’s all too easy to put something like this off, but please do contact the NHS if you have any signs of cancer.”
Radio presenter and writer Deborah James, known as “Bowel Babe”, has been sharing her experiences about safely continuing treatment at the Royal Marsden on Twitter.
She said: “While coronavirus is the new big C in everyone’s lives, it doesn’t stop cancer killing people too. It’s still a threat and not just for those who are already diagnosed – you must check yourself for symptoms.
“For anyone who is worried about having their treatment during this time, the NHS is still there for people like me and you – it might look slightly different but the staff and the care remain the same.”
Professor Peter Johnson, NHS clinical director for cancer, said that waiting to get help can have serious health consequences now and in the future.
He said: “We cannot let Covid become a reason for people not to get checked for cancer – NHS staff up and down the country have worked very hard to make sure that tests and treatment can go ahead quickly and safely.
“Cancers are detected earlier and lives are saved if more people are referred for checks, so our message to you is to come forward – it could save your life.”