The Symons' family confirmed the tragic news after releasing a statement to 3AW on Wednesday morning.
"It is with the deepest sadness Red announces the passing of his beautiful son Samuel Symons."
"Samuel passed peacefully overnight surrounded by his family."
"We ask that you please respect the privacy of Red and his family at this very sad and difficult time."
Since the age of 4, Samuel was a patient at Melbourne's Peter Macllum Centre - following a brain tumour diagnosis.
He lived with secondary cancer for the rest of his life.
Back in 2010, he and his family spoke on Australian Story.
"Even at this stage in Year 12 I still have thyroid cancer and I still have a brain tumour in my head which is a little bit off-putting," he shared.
"I used to think what it would have been like if I didn't have cancer but what's the point of thinking about the past when you can just think of now?"
This May, Samuel received the Outstanding Achievement by a Young Volunteer Award at the Minister for Health Volunteer Awards for his dedication to helping people living with cancer.