Local hospitals are struggling to see patients suspected of having breast cancer quickly enough.
The Mid Yorkshire Hospitals NHS Trust, which runs Pinderfields, Pontefract and Dewsbury Hospitals, is currently seeing just 68 per cent of people referred for an urgent appointment by their GP within two weeks.
A meeting of the trust board on Thursday heard that there was still a backlog of patients waiting to be seen by a specialist, despite the hospitals putting on "more capacity than ever before" for breast cancer services in January.
A report on the issue said that a spike in the number of referrals, and staff sickness and leave in radiology departments, where patients are scanned, were factors behind the problem.
The trust's director of operations, Trudie Davies, said: "Right now, we're doing everything we can about this internally, but there's no easy answer.
"We did outsource some of the work to a third party provider, but we couldn't sustain good performance because they weren't open over Christmas and bank holidays.
"The service they provide just wasn't available.
"In January, we've tried to compensate. There's been no shortage of capacity - in fact we're put on more capacity than ever before, but there's been a huge spike in demand and referrals."
Ms Davies said that similar issues were being reported across the country.
She added: "Every trust is under pressure. It's not just ourselves.
"There's been a drop in cancer performance across West Yorkshire, but we can't really pinpoint why we're getting more referrals at the moment.
"It's at a level where it is a concern."
Government guidelines say that at least 93 per cent of people referred to a cancer specialist by their GP should be seen within a fortnight.