Around 120,000 women have not been screened for breast cancer in the last year as a result of the pandemic.
BreastCheck screening is to resume within the next two weeks after the service was suspended again over Christmas.
Invitations are being sent out this week, with the first appointments scheduled for March 8th.
It comes as part of efforts to resume non-COVID healthcare services while other level five restrictions remain in place.
Head of BreastCheck Professor Ann O'Doherty told Lunchtime Live the service has lost nearly a year worth of screening time.
While services temporarily resumed last year, there was fresh disruption when the third wave of COVID-19 worsened around Christmas.
Professor O'Doherty said: “We very reluctantly made the decision to stop screening over Christmas because the numbers in the community were so high.
“At the same time over Christmas, we had a number of outbreaks in our own units.”
She said she'd never seen hospitals like they were over Christmas, as they were “absolutely full”.
She said: “One of the most important things if we’re going to screen healthy women is at all costs we’re going to do no harm.
"There was a very significant risk to women if we brought them out at that stage.”
“Sadly, we’ve lost almost a complete year of screening. This time last year, we had to stop screening… Somewhere around 120,000 women have not been screened that we'd [have] liked [to screen].
She assured people that staff have continued working in hospitals, looking after anyone with symptoms.
Staff are now vaccinated, and routine screening is restarting at the “first opportunity we can”.
“We will be doing everything in our power"
Professor O'Doherty said they'll be creating "a big a list as possible" for screening when it resumes early next month.
She said: “The other thing to say is we screen women every two years… unlike in the UK where it’s every three years. We have a little bit of wriggle room the UK doesn’t have.
“That’s not to say we’re happy: we’re keen to get back and get our normal screening activity, and save as many lives as we can.”
She says most women due for a check this year may have to wait as those who missed an appointment over the last year are checked.
She explained: “We will be doing everything in our power, but it probably won’t [happen] for most people I think is a realistic thing to say… we can’t catch up on a full year.
“Even if the Government was to give us a whole load of money, it won’t make any difference.
"What I would love the Government to do is give us money to help our symptomatic services, as they are inundated with more women than normal.”
She urged anyone who currently has symptoms - such as a lump, inverted nipple or a red inflamed breast - to not wait for their BreastCheck appointment, and to instead go to a hospital now in order to get tested.