National MP Nikki Kaye says she tried to resign when she found out she had breast cancer, but then-Prime Minister John Key refused to let her.

LISTEN ABOVE: PART ONE OF NIKKI KAYE AND LAILA HARRE WITH MATTHEW HOOTON (PART TWO CAN BE FOUND HERE)

Kaye and former Internet Party leader Laila Harre joined Matthew Hooton this morning on Newstalk ZB to discuss breast cancer.

Talking about the practicalities of dealing with her September diagnosis, Kaye spoke of calling Key to tell him she was sick.

"I offered my resignation and he refused to accept it, which was pretty incredible," she said.

"I was a complete mess. He was really strong and just said 'nup, you're going to get through this and we'll switch the portfolios'."

Kaye said she had enjoyed a new closeness with her family since finding out she was sick, but telling her mum was "very, very hard".

"It was my mum's birthday so I actually delayed telling her by a day. My family has been amazing but I actually saw my mum's face crumple."

At 36, Kaye said it was a fluke she found the lump in her breast as she had not yet started getting mammograms.

The diagnosis "broke" her life and meant her career as a promising young politician had to be put on hold.

"One moment I was on my way to Wellington, the next minute I was on a table getting poked and prodded and had essentially stepped aside."

Now Kaye is planning her return to parliament, but getting well is her number one priority.

Kaye said the diagnosis was still "raw", but a positive result of finding out she was ill had been a new outlook on life.

"Now I just don't worry about the little things I used to worry about.

"I just think 'frick, I'm alive, it's sunny'. I hope that's a permanent new state of mind."

Harre, who also faced a breast cancer diagnosis in 2011, encouraged women to get checked regularly, a sentiment Kaye echoed.

"I think one of the things I've learnt is that everybody has a different journey and there are lots of different kinds of breast cancer," said Kaye.

"It can be more aggressive in younger women."

She recommended even younger women get a mammogram, and if they felt anything unusual to go to their GP and get referred right away.

"Don't muck around," she said.

"In the scheme of things it can be the difference between saving your life and you've just got to go and do it. It takes a couple of minutes."