NEW YORK - Michael Buble has said on Facebook that doctors treating his son Noah for cancer are "very optimistic" regarding his progress.

The Canadian singer announced in November (2016) that he and actress wife Luisana Lopilato were putting their careers on hold while three-year-old Noah was undergoing treatment.

He did not say what kind of cancer his son was suffering from.

On Friday (Feb 3), 41-year-old Buble thanked well-wishers for their support and said Noah is "progressing well".

"We are so grateful to report that our son Noah has been progressing well during his treatment and the doctors are very optimistic about the future for our little boy," Buble wrote.

"He has been brave throughout and we continue to be inspired by his courage. We thank God for the strength he has given all of us. Our gratitude to his doctors and caretakers cannot be put into words."

He went on: "We'd like to thank the thousands of people that have sent their prayers and good wishes to us. As we continue this journey we are greatly comforted by your support and love."

Buble had spoken in November of the couple's devastation at learning their son had cancer.

"Luisana and I have put our careers on hold in order to devote all our time and attention to helping Noah get well," Buble wrote.

"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."

Noah is the first child of the couple who married in 2011. Their second son, Elias, was born in January.

Buble has carved an international career and won four Grammy awards with easy listening pop songs like his 2009 hit Haven't Met You Yet?