Some 364 women were this evening informed by the Health Service Executive (HSE) that they will not require follow-up checks after a review of ultrasounds and case notes at Midland General Hospital.
Fine Gael and the Labour Party, meanwhile, have both put down motions of no confidence in Minister for Health Mary Harney to be debated in the Dáil next week.
The HSE this evening confirmed that 364 out of 568 cases under review had resulted in no recall of patients for futher examination.
"All are being contacted today, and where unable to speak to them directly, messages have been left. Letters are also being sent to those patients," a spokeswoman said.
"Review of outstanding clinical notes is continuing in the hospital," she added.
Fine Gael leader Enda Kenny
Ms Harney separately announced that the clinical review of the 97 women who are being recalled will begin tomorrow.
The Minister said as many women as can be contacted by the HSE will be offered their review tomorrow in Midland General by a team lead by Professor Arnie Hill, Consultant Breast Surgeon at Beaumont Hospital.
The service will be available on Monday for those who cannot be contacted, she added.
"Arrangements are in place to ensure that any woman who requires further evaluation will have that provided," the Department of Health said in a statement. These will be carried out at St Vincent's Hospital, Dublin, on Monday afternoon, and, if necessary, on Tuesday afternoon.
The Minister has also instructed her officials to meet with the HSE tomorrow and Sunday afternoon to monitor progress on these arrangements.
This evening's developments follow calls for Ms Harney's resignation over the crisis in cancer services and in particular the reviews of breast cancer services at Midland General Hospital in Portlaoise.
Fine Gael leader Enda Kenny said today he had "no choice" but to conclude it is time for Ms Harney to step down as Minister.
"The Minister's explanations for the failure to immediately inform 97 women that they needed a further medical check arising from concerns over ultrasounds taken in Portlaoise hospital are unacceptable," Mr Kenny said.
He said the Minister was "so disengaged ... so removed from the reality on the ground that we cannot have confidence in her ability to run the health service".
Mr Kenny added the handling of the crisis in relation to misdiagnosis of breast cancer cases in Portlaoise was not "patient-centred" but "system-centred".
"I don't believe in the politics of calling for resignations of every Minister who shows incompetence. But the point has come when we have to say stop. That point for Minister Mary Harney is now."
The Labour Party has also tabled a motion of no confidence in the Minister to be taken on Tuesday and Wednesday.
Labour spokeswoman on health Jan O'Sullivan said motions of no confidence in a government Minister are only merited in the most serious of situations.
"However, the disclosures about the failures in cancer screening and care at the Midland Hospital, Portlaoise, and the questions that have been raised about the subsequent handling of the disclosure of information by the Department of Health and the HSE are of such seriousness that they cannot be ignored by the Dáil.
"While nobody questions Minister Harney's personal integrity, the patience of the public has now expired at the continued failures in the health service on her watch."
Ms O'Sullivan said she hoped that those Fianna Fáil backbenchers and independent TDs "who have been happy to engage in whispered criticisms of Mary Harney in the corridors of Leinister House will now have the courage of the convictions and come into the House and put those views on the record".