Te Whatu Ora Southern has apologised following the Health and Disability Commissioner report, and said it has taken immediate action to address the concerns highlighted.
The report examined non-surgical cancer service delivery between 2016 and 2022, and said it was clear that care provided was not adequate.
Patients had been harmed by capacity issues and delays in obtaining first specialist assessments, the report said.
Retired radiation oncologist Lyndell Kelly said "everybody" knew the situation was occurring, and she had stood for the Southern District Health Board in order to voice her concerns.
"Clinicians were sidelined and disrespected for the sake of the budget," she said.
It was a "terrible time" and a failure of many systems, she said.
The future seemed grim for radiation oncology, especially as the new Dunedin hospital building would not include a new oncology department.
Cancer Society Otago Southland division chief executive Rachael Hart said wait times and their human impact had also been flagged as a concern by the society.
"It’s horrendous to hear what we’ve known anecdotally for some time".
Te Whatu Ora needed to make changes so that no-one would face a similar situation in future, she said.
Te Whatu Ora regional hospital and specialist services director Dan Pallister-Coward said the organisation "apologised unreservedly" to patients and families who had been impacted.
"We are fully committed to implementing the commissioner’s recommendations and have taken immediate steps to address the highlighted concerns," he said.
Changes included recruiting for up to three more radiation oncologists in addition to Southern’s current four, and use of locums.
A national oncology forum had also been set up to address the situation in Southern.
Telehealth, private providers, and collaboration with Canterbury radiation oncology helped to support patients.
Clinical governance and accountability processes had also been strengthened in the last two years, and a working group met weekly to monitor the waitlist.
These actions would reduce the likelihood of future system or process failures, he said.
Te Whatu Ora Southern acknowledged that clinicians were not under criticism in the report, and thanked them for their hard work and dedication.
The organisation was committed to delivering exceptional cancer services to the community, and patients were encouraged to contact their treating team to discuss any concerns.
"Our teams are working hard to support our patients and their whanau as we navigate through these challenges."
