Former schoolteacher Breeda O'Connor was diagnosed with an aggressive and hard-to-treat form of breast cancer which developed in between her two-yearly screening with BreastCheck.
Ms O'Connor, from Portumna, Co Galway, said the stage three triple-negative cancer developed a year to six months before she took up the routine BreastCheck invite of a free mammogram.
She is now anxious that when BreastCheck eventually resumes, after being suspended since March due to the Covid-19 pandemic, the screening gap will have to be extended from two to three years.
BreastCheck said it has no alternative but to stretch the interval to three years because of the backlog of over 70,000 which has built up, as well as the demands of infection control which will slow up the process in its units.
"It was my second mammogram with BreastCheck in 2011. The first was in 2009.
"I had no symptoms and they told me it would never have been picked up through a physical examination.
"The tumour was tiny, around 1.3cm. It had gone to that stage that quickly.
"My experience with BreastCheck was excellent," said Ms O'Connor.
"I had chemotherapy, surgery and radiotherapy.
"I was diagnosed at the end of August and by the end of September, I had started treatment.
"The whole experience was over in eight or nine months. They gave me a timeline when I started and everything happened. I am cancer-free since.
"I would be worried about the three-year wait. A lot can happen in three years," she added.
BreastCheck said it has been screening more frequently than in England, which screens every three years. A spokeswoman said: "This is in line with international best practice."
She added that the pause in screening, combined with Covid-19 restrictions, means it will take some months to catch up. "It is therefore projected that it will take 36 months.
"Although we would not wish anyone to have a longer interval for screening in Ireland, there is no evidence that harm will accrue from a delayed screen. BreastCheck in Ireland screens more frequently than in England, which screens every three years. This is in line with international best practice.
"The National Screening Service continues to encourage all people who are between appointments, or waiting for rescheduled appointments, to be aware of, and act upon, any symptoms."