Instead, Woods said her 75-year-old partner became very unwell, constantly tired, short of breath and struggling to make it through each day.

"Up until this point he had always been very fit. We did competitive ballroom dancing together for nearly 20 years and enjoyed bush walking. I was scared."

Reaching breaking point, Woods booked an appointment with private cardiologist Dr Miles Williams in June last year.

It was then they discovered that it was not Collinson's heart that was causing his symptoms but a growing cancer in his neck and chest.

Woods said Williams went back over the notes and found the chest scan that had not been followed up by the Hawke's Bay District Health Board radiologist.

"He ordered an upper body scan and the results showed metastasised cancer with a growth in his L5 vertebra which had fractured his spine and was causing his back pain."

By this stage the three lymph nodes had grown, the biggest 27mm.

Medical director of Cancer Society New Zealand and oncologist Dr Christopher Jackson said he could not comment on the specific case but said the earlier the diagnosis the better.

"Obviously we want to get a diagnosis as early as possible so we can start treatment before it spreads.

"At the moment the Government is only reaching 15 per cent of people who have cancer in the very early stages so there are a lot of people out there with cancer who have not been diagnosed and this is definitely something we need to work on," Jackson said.

At that point, Collinson was sent to Cranford Hospice for pain management before flying to Palmerston North Hospital for five days of palliative radiotherapy to his lumbar spine.

He died a month later at home with Woods by his side on October 3, 2017.

Woods said after her partner passed away Williams told her it was simply not acceptable that the scan was not followed up and an investigation would need to be done.

The Herald approached Williams for comment but was unable to get a response.

"I haven't heard anything since. I didn't go back to ask because I was so caught up in Lindsay's death. It's been really awful, I'm lost as to how this happened," Woods said.

Hawke's Bay District Health Board physician and chief medical and dental officer Dr John Gommans confirmed that the board was investigating a delayed diagnosis following a CT scan at Hawke's Bay Hospital in 2016.

"Full disclosure was provided to the family following the discovery of the delayed diagnosis in 2017, and an internal investigation was launched. This incident was also notified to the Health Quality & Safety Commission," Gommans said.

He said Hawke's Bay District Health Board unreservedly apologises to the family of Mr Collinson for the distress and grief this has caused.

"The DHB also acknowledges family should have been kept informed during our review process."

Gommans said the DHB attempted to contact the family to apologise and explain where the investigation was at.

"The DHB has committed to completing the investigation this month and sharing the findings of the review."

Woods has submitted a complaint to the Health and Disabilities Commission and is awaiting a response.