The Chief Executive of the National Screening Service has said she believes trust has been "fractured" between the public and screening services in the last couple of years.

Speaking on RTÉ's Today with Claire Byrne, Fiona Murphy, who took up the post in July, said that those who run screening services could have better explained the limitations of screening and the potential harm that can be caused by it.

"People trust it in that they still come forward for screening.  They understand the benefits of screening," said Ms Murphy.

"But I think some of the relationship between the public and screening has fractured in the last couple of years. And part of that I think is that we've always been very good at telling people what the benefits of screening are and they undoubtedly save lives.

"But we've been less good at telling people about the limitations of screening and all screening programs cause some harm. And our job is to try and reduce that harm as much as we can, by putting in quality assurance systems."

Ms Murphy explained that the three types of harm that can take place as a result of screening are overdiagnosis, harm during treatment like colposcopies and colonoscopies, and false reassurance.

"Two in every 1,000 people that we screen, we don't find anything and there is something there to be found," she said.

She said the media portrays these situations as something has been misread, but she said this is often not the case.

"In actual fact, if you put that sample back in with the other 1,000, most people won't see it. But it's different when you already know it's there. That's called retrospective bias."

Ms Murphy accepted that there have been "serious misses" in cervical screening in the past.

She said it can come as a "double blow" to people who have gone for screening, but they still develop cancer.

"If you've gone for screening, you feel you've done everything that you should do. And so it comes almost as a double blow to then find out. Well, I've played my part. And, and yet I still have cancer. I think that makes people very upset, quite rightly," Ms Murphy said.

"But the thing is that we know this at the outset, so we know that two in every 1,000 people won't be detected. And if we end up with being sued for all of those, then actually the benefit that we get from the 18 who are detected might be lost."

"Solicitors might like to go to the high court but patients don't," she added.

Ireland's cancer screening services were hit this year when Covid-19 restrictions caused hundreds of scheduled checks to be postponed.  They are back up and running now but they still face, huge logistical challenges, Ms Murphy said.

Breast, bowel and cervical are the three types of cancer, which are screened for in Ireland.

Ms Murphy said for every 1,000 people that are screened for cervical cancer, abnormalities would be found in 20 people.

She explained that the HPV test would correctly detect cancer in 18 out of those people.