Following an initial number of 28 identified in September, health spokesman Walk Secord said further patients had been identified via Pharmaceutical Benefits Scheme (PBS) records.

While the investigation by Professor David Currow acknowledged the number was not exhaustive and more could arise through the PBS, Mr Secord said more was needed.

“Simply saying it’s inadequate is not good enough, we have to find out what happened,” he said.

Mr Secord said some doctors and nurses had not co-operated, but a commission could compel them to give evidence. 

Dr Grygiel was a fly-in, fly-out medical oncologist in Orange between 1989 and 2012.

Asked why the 59 extra cases had not been released earlier, a Western NSW Local Health District spokeswoman said the LHD’s first obligation was to the patients and their families.

“The process of contacting patients, wherever possible, concluded last month, which is when the numbers were released to the ABC through the GIPA process,” she said.

“The PBS data was not received until November 2016. This consisted of thousands of line items that needed to be reconciled against patient records and then reviewed by a clinician to ensure that patients were appropriately identified.”

The spokeswoman could not confirm how many patients had since passed away or whether dosing was a factor due to privacy. 

“The process of open disclosure includes offering an apology, support and information,” she said.

“The information and support service provided throughout the process remains in place should any of those people affected continue to have questions or concerns.”

Minister for Health Brad Hazzard was unavailable for comment.