The Young family's nightmare began in November 2013 when they noticed a lump like a pimple on the back of Isaac's leg.
"My wife's a doctor and her first thought was that it looked like a melanoma, but then she said, 'No, don't be stupid' because she was very much of the opinion that you typically didn't get melanoma until you were well over 20," said Paul.
Their doctor initially thought it was inflamed tissue and treated it with silver nitrate. But it didn't go away.
A year ago, the lump turned "an interesting blueish colour" before the family was given the "shocking" news that Isaac had melanoma.
He had two operations in which a piece of skin and flesh "about the size of a bottom of a can" was cut from his leg, Paul said.
"Probably the most traumatic part for him was when the bandages came off. He was pretty freaked out by the size of the area that had been taken out."
A year on, Isaac has recovered, is back at school and playing cricket.
Paul said Isaac was extremely sun-conscious as he was very susceptible to sun burn. "The thinking with [the melanoma] is that it actually had nothing to do with the sun, which is unusual."
Isaac said a positive attitude was the key to his recovery. "Take everything as it comes and take it positively. Don't freak out," he said. "After they diagnosed it I had to change my attitude and I had to be positive about everything and believe that I was going to be okay at the end of it."
He is now on a drive to raise awareness about melanoma and other kids still fighting cancer. More than 4000 melanoma cases are diagnosed in New Zealand each year.