Skin cancer specialists say lives are being put at risk because of delays getting results back from some laboratories, with people waiting up to eight weeks to hear if they have melanoma.
One Auckland laboratory has been so slow its international standard of competence has been suspended, and Te Whatu Ora has apologised to patients.
The Royal College of Pathologists says 80 percent of specimens sent for testing should be back with the clinician within five days.
But in Wellington and Auckland patients are sometimes waiting more than a month for a diagnosis, leading to Auckland's Community Anatomic Pathology Service losing accreditation for its skin testing department.
Dermatologist Dr Louise Reiche said it was unfair for patients, as the longer they waited the more their melanoma spread.
Reiche said when a melanoma extended, it needed more major surgery to remove it under a general anaesthetic and it could have spread to lymph nodes or elsewhere.
"Not only will they suffer an extensive surgical procedure, but it could also shorten their life."
She said it was scary some pathology services were so slow, and it had been known for years that demand would increase with a growing population and more skin cancers.
Doctors' warnings to Te Whatu Ora and politicians seem to have fallen on deaf ears, she said.
Dr Gary Duncan, a plastic surgeon and spokesperson for MelNet which is trying to reduce the impact of melanoma, said patients were now having to make multiple trips to their specialist, as when they initially returned after having a lesion removed to get stitches out, their results had not come back from the laboratory.
Duncan said that meant the doctor could not discuss what was found, so patients needed to book another appointment when the results came in further down the track - or be told they have melanoma on the phone.
The longest turnaround time from when the sample was sent to the laboratory and the report was back at the doctor was eight weeks, which caused patients a lot of anxiety, he said.
Dr Jeremy Hay has a skin clinic in Upper Hutt and said the turnaround time for melanoma test results in New Zealand was weeks longer than in Australia, where he previously worked.
He had never seen a melanoma report return from the laboratory within the clinically appropriate five working days.
His local pathology lab just could not keep up with the number of samples waiting to be tested, he said.
"I have visited the lab, and you can see even in the corridors stacks of unreported slides sitting outside the pathologists rooms, and there are more inside their rooms. They need more staff and that's quite obvious."
As a result he does not often start with biopsies on suspicious-looking skin samples any more - he gets out his scalpel and sends the whole thing off to be tested.
Te Whatu Ora declined to be interviewed, but in a statement said most districts were meeting turnaround times and did not have a backlog.
It said the Auckland laboratory service which lost its accreditation could not cope with the heavy workload and was short-staffed.
It was still operating, but samples were being sent to other laboratories outside Auckland.
Te Whatu Ora apologised to the people who have been waiting longer than was appropriate and for the distress this may have caused.