With chemotherapy no longer working and surgeons unable to operate, his only option is a non-funded medicine called Avastin.
Ryan needs a course of medication every two weeks for the rest of his life, costing more than $50,000.
Avastin will not cure the brain tumour but will hopefully stop it from growing any bigger or at least slow it down, sister Nadine Nairne says.
His family have been fundraising and started a Give-a-Little Page to pay for the treatment which has so far raised more than $18,000.
"We just want to give him a better quality of life," another sister Jodie Penn says.
Ryan's children fly up from their home in Christchurch to spend the school holidays with their father. Jodie believes it is spending time with family that keeps her older brother going.
As well as his own three children, Ryan loves spending time with his 27 nieces and nephews.
PORSE Whanganui office is helping organise the Boerboom Family Gala this Saturday with all funds going to Ryan's treatment.
"Ryan was a very special educator," PORSE Consultant Donna Hyland says.
"He has a real zest for life and he constantly stuns people with his positivity. We at PORSE want to do what we can to make sure he can spend more time with his family."
The team have organised family activities for the gala day.
Jodie says PORSE and the wider community have been amazing with their support.
"Ryan and his children need to have more time together. They are far too young to lose their dad, and Ryan is planning on making many more lasting memories with them," she says.
The Boerboom Gala Day will be held at the Marton Memorial Hall on Wellington Rd on Saturday June 17.
To make a donation visit: https://givealittle.co.nz/cause/helpsaveryanboerboom