Caleb Jackson started going through puberty four years early, and his parents had no idea why.
Now his mum wants Caleb's story to act as a cautionary tale. She wants to help other families spot brain cancer sooner.
"I just want other people to have questions answered a lot quicker than we did," she told Seven Sharp.
Caleb went for an MRI last May, aged seven, because he was growing up too fast both physically and emotionally.
"He was very impulsive, very aggressive at times," mum Alice said.
"If you think of a 12-year-old, his behaviour became a bit like that.
"Normally he's very compassionate, very calm, he's gentle."
That scan changed all of their lives. It showed Caleb had a brain tumour.
That tumour was fast-tracking puberty, pressing against the pituitary gland at the top of Caleb's spine — and the bigger it grew, the more it impeded Caleb's eyesight as well.
"He would read one word at a time, and then he'd be 'oh, I've lost my place'," Alice said.
"All of his optical nerves are basically intertwined, so yeah, you've basically got to try and shrink it... It's inoperable."
But Caleb, now eight, is determined to handle the treatment process as best he can.
"I know that I don't really want to do this," he said.
"And it's honestly not the best thing in the world to do. But I know I have to do it."
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