David Bingham: "We will try to estimate demand"

There are shortages of radiologists, of other specialist doctors, radiographers and specialist nurses.

The Department of Health has said it is keeping a close eye on the situation.

Workforce planning

Spokesman David Bingham said: "Northern Ireland is a small place, we are dealing with relatively small numbers, and it only takes one or two people to take a change in career or move elsewhere, and then the whole equation is disrupted.

"That is why the department will be saying in our workforce planning that we will try and estimate demand - and then add on some."

Great strides have been made in cancer care recently, which mean more people are treated by experts.

But the leaked memo says the problem of recruiting enough staff to "sustain the continued improvements" in cancer services "is likely to continue for some time".

It adds that it has the potential to "detrimentally affect not only cancer services, but also acute services".

Arlene Spiers: "Hearing of problems from patients"

However, cancer is not the only area in the health service which suffers from a shortage of staff.

Shelf life

But in the last five years nothing has had a higher priority than cancer.

Arlene Spiers of the Ulster Cancer Foundation said: "We are hearing problems from patients about how long they have to wait for scans and how they have been turned away for treatment."

Last month, the Department of Health said it was giving urgent consideration to buying more than �1m worth of radiotherapy equipment for Belvoir Park Hospital in Belfast.

The site at Belvoir, which houses Northern Ireland's only radiotherapy facility, is due to close when a new cancer centre at Belfast City Hospital is complete.

Much of the radiotherapy equipment at the site has reached the end of its recommended shelf life.