Cancer patients are being promised their treatment won't suffer despite strike action from radiation oncology workers.

Medical physicists from Auckland, Waikato, Capital and Coast, Midcentral, Canterbury and Southern DHBs will begin strike action this week.

The medical professionals standing up against the fact would get paid between 30 to 50 percent more if they worked in Australia.

APEX union advocate David Munro argues our government pays to train oncology but won't pay to keep them.

"We've got a situation now where New Zealander's taxes are really paying for cancer treatment in Australia," he said.

"If we don't do something to match those salaries in New Zealand in a very short period of time we won't be able to run the services to the standard that we currently do."

Health Minister Jonathan Coleman has met with the Director-General of Health to make sure treatment won't be delayed, but says the rest of the strike action has got nothing to do with him.

"That's for the union to determine and they will know what their obligations are around that," he said.

"The action we've been advised of is going to be pretty limited."