Mr Colquhoun and his wife, Kathy Hancock, were then seen by specialists at Auckland City Hospital who told him he had at least two tumours in his throat, and recommended radiation and chemotherapy.
The cancer was assessed as being "moderately-fast growing", he said.
After being approved for a trial of a new type of chemotherapy drug, he began treatment on October 29.
Weekday radiation treatments began the following week, he said.
"I went through the system incredibly quickly and it was incredibly valuable as a family for us to be able to do that. Speed is everything."
Test results also indicated a third tumour might have been growing.
"What that tells me is that had I been three, four, five weeks later ... it could have been a completely different situation for me."
The Government's new two-month deadline was a huge positive, he said.
"It's an evil disease and in some cases can move so fast, and even if it's not highly aggressive, you lose options most probably every month."
Mr Colquhoun said the likelihood of success was about 80 per cent.
His treatments are due to end on Christmas Eve.