Michael Buble's son is doing ''perfect''.

The 42-year-old singer and his wife Luisana Lopilato were left devastated when their son Noah, who turns five next month, was diagnosed with liver cancer in October 2016, but he's thankful the youngster has responded well to treatment and they are no longer living ''in fear''.

He said: ''He's perfect. Clinically speaking, it was a tumour within the liver.

''And the most important thing was to get it out, with clean margins. Because if you do, it goes from being this scary thing to just being tremendous odds.

''No one likes talking about percentages but, honestly, [we have] a percentage where we can live our life, and not live in fear every day. We know we're OK now. But what we went through was f***ing brutal. I'm sorry for the language but...''

The 'Feeling Good' hitmaker - who also has two-year-old son Elias with Luisana, who is due to give birth to their daughter later this month - admitted it was a fraught time in their lives and even regular meetings with doctors never gave them comfort or hope.

He told the Evening Standard newspaper: ''You don't get reassurance -- you get the opposite. Everything that they tell you is the worst-case scenario.''

Michael finds it hard to talk about his son's ordeal but he and his wife want to help other families, leaving him feeling conflicted.

Recalling meeting a woman on a children's hospital ward in Vancouver, he explained: ''She said to me: 'Would you forgive me for saying something terrible?' I said: 'Ah... OK...' And she said: 'I was happy when I read about you'. I said: 'What?' 'Well, I knew that it wasn't just me. If it could happen to you, to your son, then, hey, it could happen to all of us'.

''I just don't talk about this... But it's such a deep conflict within me. That's something my wife and I talk about a lot: we feel this sense of responsibility to help other parents. But at the same time, it's my kid's life. This boy is a hero. He's my hero.''