Bolton NHS Foundation Trust is not meeting its targets for referral to treatment times with more than 25,000 patients on 18-week waiting lists.
Around 15 per cent of patients were not treated within an 18-week period and targets will not be achieved this year.
A total of six patients have been on a waiting list for more than a year.
This comes after it was revealed that A&E is “extremely busy” with patients waiting up to 14 hours for a bed.
Chief operating officer Andy Ennis told the board of directors that every department is facing the same struggle with waiting times.
He said: “My only concern is that we are going to get worse month on month. My instinct is that we’ll be able to stabilise at best.
“I can’t give assurance to the board that we are going to do any better. I’m really confident that our team are doing everything they can.
“Volumes are going up. Every month this year we are seeing volume of patients going up.”
However, Mr Ennis highlighted the fact that the health trust is still receiving positive feedback from patients after a performance report on services was described as a “sea of green” by directors.
Following the meeting, he said: “In line with many other trusts in the country, we have seen an increase in urgent and cancer referrals year-round, which we treat in order of urgency.
“This increase, along with a set budget and time available to treat patients, has meant that some people needing more routine treatments have unfortunately had to wait longer.
“We are constantly looking at ways for how we can provide our services more effectively, including refreshing the way we provide outpatient appointments, and are working with our commissioners to ensure that we are making the best use of the resources available to us.”
Despite being in a “vulnerable” financial position, there was also some optimism about the budget at the board meeting last week.
Finance and investment committee chair Alan Stuttard told the board that NHS Improvement is looking at Bolton “quite closely” in a way it has not done with health trusts that do not have a “deficit plan” in place.
He said: “They clearly are focusing on this sense that we are adrift from plan. In one sense that’s a positive from NHSI. They are hopefully looking at it as they don’t want us to get into that position, particularly looking forward. There’s a lot of work going on into actually addressing the deficit.”
Bolton NHS Foundation Trust had a deficit of £7.7m at the end of August with an overall shortfall of £4.3m against its plan.
There is a collective deficit of around £49m in all NHS trusts across Greater Manchester.