Michael Buble and Luisana Lopilato have been told that their son has a 90 per cent chance of beating this cancer.
Noah was reportedly diagnosed on November 1 after medics carried out a liver biopsy, following an examination at a clinic in Buenos Aires, says Argentinian magazine Gente.
Luisana’s elder sister Daniela has told the magazine: “Cancer is a horrible illness but we have faith in Noah being able to overcome this.
“We know he will. The time to start a long and very difficult treatment has come but it’s got to be done.
“They say children are normally strong to put up with chemotherapy and my nephew is a warrior.”
Noah is reportedly getting treatment for cancer in LA. Here’s a video Luisana put up on Twitter in September of Noah singing:
This latest update comes after the singer and his artist wife confirmed Noah’s diagnosis a few days ago.
They said in a statement at the time: “We are devastated about the recent cancer diagnosis of our oldest son Noah who is currently undergoing treatment in the US.
“We have always been very vocal about the importance of family and the love we have for our children.
“Luisana and I have put our careers on hold in order to devote all our time and attention to helping Noah get well.
At this difficult time, we ask only for your prayers and respect for our privacy.
“We have a long journey in front of us and hope that with the support of family, friends and fans around the world, we will win this battle, God willing.”
The singer has embraced fatherhood - his youngest son Elias was born in January - and enjoyed sharing his love of family with his legion of fans.
He said in an interview with Entertainment Tonight in October: "I love them more than I'll ever love anything, or anyone in the whole universe.
“I think it gave me perspective on life that I think I very badly needed. It's hard to be able to quantify that level of love. I didn't know that level of love existed. But it makes me better at everything. It allows me to pull more emotion and be more honest and to be in the moment.
“I had no idea how much I would love being a dad.
“'That's it, that's all I care about ... I love them too much probably, if there was such a thing.
"It's made everything else so insignificant, moments that I was afraid of and moments that would overwhelm me have now become a joy because I see how not serious they are compared to what is really important, which is Noah and Eli and that's it."
Here's a post Michael put on Instagram for Noah's third birthday a couple moths ago.
According to children's cancer experts, liver cancer is very rare in children, but kids often have a better outlook than adults with the same cancer, says Cancer Research UK.
Our thoughts are with Noah and his family as the fight this disease.