Sydney's St Vincent's Hospital has admitted making mistakes in its handling of a doctor.

Pressure is mounting on the NSW government to launch a special commission of inquiry into the widening chemotherapy treatment bungle at St Vincent's Hospital in Sydney.

It's been revealed in recently released documentation that of the 78 patients treated with low doses of chemotherapy by the hospital's oncologist, Dr John Grygiel, 23 have since died of cancer, three of non-cancer causes and four of an unspecified cause.

A government-ordered review into the scandal was unable to attribute their deaths however to the under-dosing.

According to The Daily Telegraph patients were treated between 2012 and 2015 but the review by Cancer Institute NSW CEO Professor David Currow, commissioned by the NSW Health Secretary, will now be extended to other patients treated over the past decade by the doctor at what is believed to be three other hospitals.

The review found St Vincent's Hospital also misled the public about the bungle and was slow to respond to concerns raised about the oncologist.

Greens MP Jeremy Buckingham said he had been inundated with concerns from people who were affected, including some who accused St Vincent's Hospital's doctors of "playing God".

"It's absolutely essential that we have an inquiry that has the full powers of a royal commission, can compel witnesses, can protect witnesses and occurs in broad daylight," Mr Buckingham said on Wednesday.

"That is the only way to restore trust in the system as this scandal widens."

Mr Buckingham accused Health Minister Jillian Skinner of "hiding behind" the two independent inquiries currently examining the bungle.

"The inquiries that are happening right now are behind closed doors. They're doctors investigating doctors," he said.

"We need something with the power of a commissioner to actually compel witnesses and make sure that this happens in a transparent way."

The government-ordered review of the scandal found staff repeatedly challenged Dr Grygiel's flat dosing and the hospital was aware of the practice as early as 2005.

The full extent of Dr Grygiel's prescribing was also still unknown, the interim inquiry report found.

In response, the hospital apologised to patients, their families and the public, and admitted to not living up to the "the high standards we set ourselves".

"We failed to appreciate the seriousness of the situation: early questions about the doctor's dosage practice should have led to a formal examination," St Vincent's said in a statement on Tuesday.

Dr Grygiel was stood down in February and is currently overseas.

His lawyer, Stephen Blanks, told AAP his client was pleased the inquiry had found St Vincent's Hospital had made incorrect statements about what disciplinary action it had taken.

Mr Blanks said his client was looking forward to giving his evidence to the inquiry when he returns next week.

News break – April 6