Concern is growing that people will suffer a delayed diagnosis of cancer due to the temporary suspension of national screening programmes due to the coronavirus crisis.
BreastCheck, CervicalCheck and BowelScreen have all been paused.
The screening programme to detect diabetic retinopathy has also had to be shelved.
A HSE spokeswoman said the move was to protect patients and staff by complying with social distancing guidelines, and to enable the HSE to redirect staff and resources to the response to Covid-19.
"The decision will be reviewed on April 19, in line with the Government's directive to stay at home to help slow the spread of Covid-19.
"The screening programmes will be restarted when it is deemed safe to do so. This will be based on HSE and Department of Health evidence received on Covid-19," she said.
She said that because screening was an opt-in service it was not possible to estimate the number of people affected by the temporary pause.
"For people within the system, assessments continue and patients are still being treated, as hospital resources allow. Results for those people who have recently been screened will continue to be processed and letters issued.
"Some clinics may not be available or may be limited due to Covid-19," she added.
She said those who were awaiting treatment would be contacted directly by their clinic if their appointment was changing.
Patients are asked not to attend their appointment if they have symptoms of coronavirus or are self-isolating.
"People should not make appointments for screening at this time. Those with BowelScreen kits should not return them at this time," said the spokeswoman.
"People who are in between screening appointments, or waiting rescheduled appointments, should continue to be aware of and act on any symptoms associated with the conditions being screened for.
"If they have any concerns about symptoms they should contact their GP immediately."
For other queries patients can call the NSS Freephone line, 1800 45 45 55, email email@example.com or contact their clinic directly.
Meanwhile, University College Cork has opened a centre to deliver chemotherapy to cancer patients during the Covid-19 crisis.
Part of its School of Nursing and Midwifery has been transformed to facilitate patients, avoiding the need for attending Cork University Hospital and Mercy Hospital.
Visit our Covid-19 vaccine dashboard for updates on the roll out of the vaccination program and the rate of Coronavirus cases Ireland
Dr Austin O'Carroll is a big fan of art. The GP, who is leading the new Dublin Homeless Covid-19 Response team, used to work in a clinic in the north inner-city. Things were stolen all the time. He once walked in on two people trying to take out a fireplace with a pickaxe. Against the advice of everyone, he put up art in the clinic. The theft stopped.
Business groups and parents of secondary school children have called on the Government to set out how it plans to ease the extraordinary restrictions imposed due to the coronavirus crisis.
Emergency restrictions will not be eased until our coronavirus testing regime is improved to the point where it is possible to "hunt down" positive cases and contacts within 24 to 48 hours, chief medical officer Dr Tony Holohan warned.