Community breast cancer screening services have been suspended for at least three months to prevent the spread of coronavirus in South Australia, where the number of cases has climbed above 250.

Key points: Breast screening services have been put on hold for three months

Breast screening services have been put on hold for three months BreastScreen SA says it is to protect women and staff from the risk of coronavirus

BreastScreen SA says it is to protect women and staff from the risk of coronavirus Some cancer support groups say it could lead to other risks, but they may be outweighed by the benefits

SA Health said there had been 22 new diagnoses in the past 24 hours, including another nine linked to the Ruby Princess cruise ship — taking the total to 257.

Six people are now confirmed to be in intensive care at the Royal Adelaide Hospital, with the latest cases including a 46-year-old woman and two men aged in their 70s.

SA Police said 122 staff were currently in self-quarantine and that an officer who had been overseas had tested positive.

A healthcare worker at Adelaide's St Andrew's Hospital has also been diagnosed with coronavirus.

The hospital said the staff member came into close contact with two patients and "casual contact" with staff and another two patients, but that the risk of transmission was low.

BreastScreen SA said it had made the "difficult decision" to close metropolitan screening clinics and mobile units as a precaution, to protect clients and staff.

The agency provides 90,000 free screening mammograms to South Australian women each year, and aims to detect of breast cancer in women over 50 before lumps can be felt.

"The closure is a precautionary measure and is not due to a suspected case of COVID-19 at its facilities," general manager Niamh Wade said.

The decision follows advice from radiological authorities, as well as similar moves interstate and in New Zealand, and has the support of Cancer Council CEO Sanchia Aranda.

"It's a complex decision but principally it's around protecting our health services as they face the onslaught from the COVID-19 pandemic," Professor Aranda said.

"For the majority of women, it's unlikely to be a problem."

BreastScreen SA said anyone requiring assessment and further testing would be offered new appointments, and anyone who had recent tests would have results within the next two weeks.

Clinical director Dr Michelle Reintals said BreastScreen SA was "deeply sorry" for the impact it would have, "but it must adhere to the social distancing regulations".

She urged women to carefully monitor their individuals situations.

"This includes taking notice of the look and feel of your breasts," Dr Reintals said.

"If you notice something unusual, like a new or changing breast lump, nipple discharge or any other change that is not normal for you, please see your GP as soon as possible to have it investigated."

Move 'could be very dangerous' for some women

About 10 per cent of South Australian women develop breast cancer before the age of 75, and BreastScreen SA said early detection could lead to "more successful outcomes".

"It's our view that the temporary pause is likely to cause some harm, but it won't be as harmful as continuing to go outside and go about your normal business," Professor Aranda said.

Several cancer support groups said while they understood the need to control the spread of coronavirus, the decision to postpone services could lead to crucial delays in detection.

BreastScreen SA says it is "deeply sorry" but made the decision to protect clients and staff.

Jackie Otworowski from the Blackwood Hills Breast Cancer Support Group said it was a difficult dilemma.

"It could be very dangerous if you have a fast-growing tumour. Other people it might not be so dangerous for.

"It's very confusing for people when there are so many forms of contact that are still allowed."

Such contact includes hairdressing, which remains permitted for now — but Emma Schulz from the Naracoorte Breast Cancer Support Group said the risks of close contact in a screening environment outweighed the potential benefits.

"With the message being stay at home unless you have to go out, I think it is a necessary move," she said.

"Maybe there's a risk but I think there are ways of minimising that risk through education and different forms of doing that, ie over the phone, telehealth, maybe talking with GPs."

Ms Wade said once serviced resumed, women who missed regular mammograms during the suspension period would be prioritised.

"The mobile screening units will return to their current locations to complete their visit, while extended screening hours will be offered to ensure no rural and remote women are disadvantaged," she said.