Fleetwood Mac's bassist John McVie has been diagnosed with cancer, the band revealed Sunday on Facebook.

A co-founding member since 1967, McVie is set to begin treatment soon. Subsequently, the band has canceled its upcoming Australia-New Zealand tour.

“We are sorry to not be able to play these Australian and New Zealand dates," said Fleetwood Mac in a statement. "We hope our Australian and New Zealand fans as well as Fleetwood Mac fans everywhere will join us in wishing John and his family all the best.”