If your friend is a New Zealand citizen, then she will receive free care in New Zealand.
The best way for her to move into the New Zealand system would be a referral from her radiation specialist there directly to the hospital in the centre where she is moving too. There may be a wait of up to 4-6 weeks from referral arrival so the sooner it is started the better. If she is having any treatment presently, then they can allow this to continue with the least possible interruption. A referral can be made by a gp here once she returns, but a specialist to specialist referral will be faster.
Either of you are welcome to email firstname.lastname@example.org if you want to talk about different centre’s that give treatment or who to contact.
I hope this helps,