An oncologist told the Herald the length of time patients were having to wait was a serious concern and reinforced the need for a national standardised system.
In January, 10 out of 34 patients referred to Counties Manakau DHB with a high suspicion of cancer waited longer than 62 days for urgent treatment.
This meant only 66 per cent of patients were being seen within the target timeframe and it was expected to worsen next month when the impact of the strikes settled in.
Counties Manukau DHB general manager of ED, medicine and integrated care Brad Healey said there were three main reasons for the excessive wait times over this period, including workforce shortages, lack of resources and the administration process.
"The pressure on all services is putting stress on the system so whilst we make every effort to mitigate, you can't mitigate everything."
Talking to workforce shortages, Healey said it would be unaffordable to staff the hospital for maximum volumes all the time.
"It would be a waste of tax payer money. Yes, there is a lack of staff but we can't pluck specialists out of thin air," Healey said.
The DHBs service manager for cancer and palliative care Anne-Marie Wilkins said the performance drop in January was not due to strikes but more staff taking leave or getting sick over the summer holiday period.
However, during the previous summer holiday period the DHB maintained the target right the way through.
They agreed the recent performance drop was a huge concern and there was a lot of work being done to improve it.
Wilkins said head and neck, lung, breast and bowel cancer were the main departments of concern and she had been working with each department to get to the root of the cause.
Out of all 20 DHBs, only seven had a record of achieving target, six fell below and six others didn't have those figures available.
Although Southern DHB did not have figures for January, in December last year only 67 per cent was achieved and 64 per cent in November.
Whanganui DHB was also failing to meet target with only four out of six cancer patients receiving urgent treatment within 62 days.
At Lakes and Wairarapa DHB all patients were seen within the targeted timeframe but that was mainly due to low demand.
Canterbury DHB seemed to be getting the best results with all 25 patients receiving their first round of treatment within the 62 days.
The seven DHBs who could not provide the Herald with their latest data included Auckland, Mid-central, Capital and Coast, Nelson-Marlborough, South Canterbury, West Coast and Southern.
Cancer Society of New Zealand medical director and Southern DHB oncologist Chris Jackson said while it was shocking to hear how long some patients were waiting for treatment, more emphasis needed to be put on the root causes.
"Our system is failing and that's exactly why we need a national cancer agency to ensure all DHBs are keeping up with a national standard of care."
The Herald approached Minister of Health David Clark for comment in the issue but he declined.
Ministry of Health director-general of health Dr Ashley Bloomfield said Ministry officials were working with DHBs who were not meeting target to understand what the issues were, and what specific actions were underway to improve performance.
"The Ministry of Health is also working on a national cancer action plan to improve collaboration between DHBs, their clinicians, and the wider cancer care sector. The aim is to improve national consistency of services, equity, and health outcomes for people with this disease," Bloomfield said.
*Due to an error made by the Herald Capital and Coast DHB have been excluded from this report.