But just before Christmas, doctors discovered the aggressive form of cancer had reinvaded the 21-month-old toddler's bone marrow.
The little battler was given 48 hours to live. He lasted 13 days.
Rachael detailed her torment in a Facebook post on December 28: "Well. It's 12:25 and Jackson has stolen another day. He is very weak and has deteriorated since yesterday. It is gut wrenchingly horrible to watch someone you love so much succumb to this hideous disease. To watch him fighting to breathe, it's heart breaking. But still he clings on. As much as I want him to live, I want his suffering to end."
Jackson died that night in Taranaki Base Hospital.
Yesterday, hundreds of people attended a ceremony at the Inglewood Town Hall. Friends held simultaneous ceremonies around the country, releasing balloons.
Rachael said they had never given up hope that Jackson would pull through.
Speaking before the funeral, she said: "For us there was no way this was going to happen in our hearts. We have got through so much with him, he was going to grow old.
"In the last couple of weeks we started to see his true personality emerge. We have lots of photos and videos of him and we can look back on that and show our 3- and 4-year-old. We are so grateful that we got to see his stroppiness and cheekiness."
Despite Jackson's illness placing a massive financial burden on them, Rachael and Darrin never sought to publicise Jackson's plight.
But the grieving couple say they are proud of the way Jackson battled every day of his life.
"I want people to know about Jackson," Rachael said, "and to know that with so many horrific stories of child abuse, that there are children that are loved."
Darrin added: "The whole 21 months of his life, this has always been a possibility. It's just been a real roller coaster ever since."
* Do you want to support the West family? Email editor@hos.co.nz
