A backlog of women waiting for breast screening will leave some patients facing a delayed diagnosis, consultants have warned.
The delay has been linked to the failure to recruit enough specialists, with 450 vacancies currently not filled on a permanent basis.
The Irish Hospital Consultants Association (IHCA) said the warning was made by one specialist involved in cancer care as part of a survey on the impact of doctor vacancies.
The IHCA recently surveyed 900 doctors about the impact of the failure to fill permanent posts.
The doctors have said the failure to recruit specialists is mostly due to the fact that new entrant consultants are paid 30pc less than long-serving colleagues.
This cut was imposed during the recession and has not been reversed.
Consultants said they do not believe waiting times will improve in the immediate future, with 80pc of those surveyed confirming that patients will see waiting lists for outpatient appointments increase over the next 12 months if consultant posts are not filled.
One of those who responded said that "waiting times are now over three years for outpatients".
Another said: "It has become a new 'normality' that I need to apologise to patients for the increasing waiting period in clinics and for being unable to see those patients after commencing therapies."
Other medics warned that there is a four-year waiting list for outpatients, with 80 new referrals in three weeks.
One said it was "absolutely impossible to continue at this level without further staffing".
"My post was unfilled for six years. Two previous candidates declined to return to Ireland," the doctor added.
A further comment from a doctor said: "Our hospital is now at a tipping point with regard to consultant recruitment.
"If we cannot recruit another consultant physician shortly, we are likely to have to close our doors out of hours."
IHCA president Dr Donal O'Hanlon said: "These survey results are stark and overwhelming. Patient care and safety is being damaged due to Government policy, which has resulted in one fifth of the permanent consultant posts in our hospitals being unfilled.
"Ultimately, patients are paying the price.
"It is no coincidence that we have some of the longest hospital waiting lists in Europe, with over 500,000 people waiting for consultant outpatient appointments.
"Government policy is destroying the fabric of hospital care for patients in Ireland."
Health Minister Simon Harris said the HSE is committed to supporting consultant recruitment and retention, pursuing a number of initiatives including improvements to the recruitment process.
"At the end of December 2018, there were 3,096 whole-time equivalent consultants working in the public health services, the highest number in the history of the State," he said.
"Notwithstanding recruitment and retention challenges, the number of consultants has increased by 125 in the 12 months to the end of December 2018, and by 540 in the past five years."