Little Noah, who just turned three in September, had travelled to the US with his mum, Luisana Lopilato, and dad Michael after they raised concerns about his health.
In a statement posted on Luisana's Facebook, Michael said: "We are devastated by the recent cancer diagnosis of our eldest son Noah who is currently in treatment in the United States. We've always talked a lot about the importance of the family and the love we have for our children. Continue...
"Luisana and I are going to spend all our time and attention to help Noah to get better, by suspending our professional activities for now.
"During this difficult time, we ask that you pray for him and please respect our privacy. We have a long road ahead of us and we hope that with the support of our family, friends, fans around the world and our faith in God, we can win this battle."