Women who avail of BreastCheck are expected to have to wait three years between mammograms when the service resumes because of the restrictions of Covid-19.
Before the pandemic struck, women were invited for the free screening - which can pick up breast cancer - every two years.
However, Dr Colm Henry, national clinical adviser of the HSE, said yesterday that BreastCheck, which will resume in September, would have to operate under a new set of procedures that would slow down the service.
"We would have preferred to go back to the way we were but nothing is going back to the way it was in healthcare," he said.
It would mean a three-year cycle of screening, he said. A backlog of around 80,000 women had built up since the service had to be suspended in March, he told 'Today with Sarah McInerney' on RTÉ radio.
It will be next year before the screening service will catch up.
BowelScreen, the programme to detect bowel cancer, will also resume in the autumn. It too had to be suspended because of the ability of hospitals to provide colonoscopies, which are invasive diagnostic procedures for people who are referred on for further investigation.
Dr Henry said the restrictions meant the volume of colonoscopies had halved.
Tallaght Hospital gastroenterologist Dr Anthony O'Connor has previously warned that people who require an urgent colonoscopy should be seen in 28 days under best practice.
"This is not happening for too many people and many more people will be left waiting for far too long unless we see steps taken now. The longer people have to wait the greater risk we are taking with their outcome if they are found to have cancer," he warned.
CervicalCheck resumes this week for high priority women - those who need a yearly recall and women who have just joined the service.
Dr Henry estimated there was a backlog of around 100,000 women whose invitation to screening from CervicalCheck had to be put on hold. The hope is that this backlog will be cleared by October and the service back to normal in February.
He advised women not to go for private smear tests and to continue with CervicalCheck.
The screening in laboratories now involves HPV testing, which increases the chances of abnormalities being picked up He urged people who may have symptoms of cancer not to delay and to contact their GP.
Ireland, which has recorded no new deaths from Covid-19 for two days, could run into trouble again if the weekend scenes of heaving revellers enjoying "takeaway pints" in Dublin city are repeated, public health doctors warned.