"Sustained investment" is needed to tackle Northern Ireland's hospital waiting list backlog, the Department of Health has said.
The comments were made as new figures revealed that more than 288,000 patients were waiting for their first outpatient appointment at the end of March.
This is an increase of 7% compared to the same period last year.
Ministerial targets state that at least 50% of patients should wait no longer that nine weeks for a first outpatient appointment, with no patient waiting longer than 52 weeks.
Almost three quarters of patients (213,708), however, were not seen within the nine week time-frame, and 33.9% (97,851) were not seen within 52 weeks.
Figures for those waiting for diagnostic tests mirror this trend.
Of the 130,351 patients on waiting lists, almost half were waiting longer than nine weeks and more than a fifth were waiting longer than 26 weeks.
Margaret Carr of Cancer Research UK said: “It’s clear urgent action is needed to tackle these issues both in the near future and the long term so the NHS can cope with increasing patient need.”
A Department of Health spokesperson said they have "repeatedly made clear" that "sustained investment" is required to address the waiting list backlog.
"The waiting times have been building up since 2014 as a result of wider financial pressures facing the health and social care system," they siad.
"With budgets increasingly stretched just to maintain existing services, funding to suppress waiting time growth has been in limited supply.
"Alongside sustained investment, longer term action is also required to prevent the problem recurring."
The spokesperson added this means "transforming" the sector by bridging the gap between capacity and demand.
In order to tackle this issue, the department is setting up specialist day surgery units with plans to transfer all routine operations to these centres by December 2020.
Earlier this month, the permanent secretary for the department, Richard Pengelly, warned that up to £1bn would be needed to eradicate waiting lists in Northern Ireland.
"We were very clear at the launch of the transformation strategy two-and-a-half years ago that it will not eradicate waiting lists," he told the BBC.
"The only way we will do that is by a very large injection of cash and we would estimate that to be somewhere between £700m and £1bn."