For presents "anything to do with Sonic the hedgehog" topped Arian's Christmas list.
In July, eight months after Arian's diagnosis, Sanaz and Nadim received some good news. A PET scan had revealed his tumour - diffuse intrinsic pontine glioma - had stopped growing.
But doctors warned it would probably start growing again in a matter of months.
By September Arian was well enough to start attending school again. He had been going earlier this year but had to stop when he became too unwell.
After returning to his class he became "energised" and more confident, Sanaz said.
"He's happier when he comes home from school than the days he's at home. I think it's the interaction with other kids."
Arian recently started having problems turning his left eye. The Truters feared his cancer was worsening, so they took him back to the doctor.
Last Friday Arian had an MRI. His parents spent the weekend anxiously awaiting the results.
"We were trying to prepare ourselves for one of the worst Christmases."
On Monday they were told his tumour was still stable.
"I just couldn't stop crying when my doctor gave me a call because I was trying to prepare myself for [the idea that] this year is it, it's our last year with him. But for them to say it's stopped growing, it just gives me hope that maybe he's got a chance to grow up."
The family would spend this summer at home, taking day trips to Orewa and Army Bay where Arian loved to swim and build sandcastles with his 19-month-old brother Ayan, Sanaz said.
She and Nadim were saving up to take their children to the United States to visit Disneyland early next year before Arian starts Year 2. Sanaz has set up a Give A Little page to fund the trip and any overseas treatment Arian might need in the future.
"We'll just take it as it comes. I hope that it continues to go well and the tumour stays stable as long as it can. But we don't have any plans for if it starts growing this year."
