"After arrival at Starship, she was given an MRI scan of the spine and brain, which revealed the tumours," her father Peter Sciascia said.
"A few days later she was operated on to remove as much of the brain tissue as possible and to take some tissue for a biopsy.
"A week later, the biopsy revealed that the tumours were seriously life-threatening."
Following the decision by Rena and her whanau to try and fight the tumours using radiation therapy, the then 15-year-old was told she could go home for a few weeks before treatment so she could celebrate her 16th birthday.
However, on the morning of her birthday, Rena was flown back to Starship, due to complications from her earlier brain surgery.
That afternoon, she underwent a second brain operation, placing a shunt in her skull to drain spinal fluid from her brain down to her stomach.
"Her recovery was slow and, after a week, she began the first of 32 treatments of radiation to her spine and brain, which ended on December 23 and allowed her to return home to recover and have Christmas with us."
Two months later, another MRI revealed a large reduction in the tumours, which steered the Sciascias in the direction of chemotherapy.
"It was decided to use chemotherapy to try and kill the remaining tumours while they were still weakened from the previous radiation treatment," Mr Sciascias said.
Rena's latest hospital admission, at the beginning of this month, was a result of complications from her third round of chemotherapy, and was followed by another MRI last week.
Sadly, the MRI showed the radiation and chemo had been unsuccessful, with the tumours still growing in Rena's upper spine.
"They have decided to cease further treatment and referred Rena to the palliative care team to help with pain management and comfort, as the disease progresses," her father said.
The family now plan to try intravenous vitamin C treatment and a course of dietary supplements called TBL- 12, shown to improve the immune system and help with the control of tumour growth.
"Rena has taken the news in her usual steadfast fashion and is busy making plans to ensure she gets the best out of what time remains for her.
"Everyone's support has been greatly appreciated."
*Donations for Rena and her family can be made through her givealittle page.