Fleetwood Mac co-founder John McVie has been diagnosed with cancer, forcing the group to cancel upcoming shows in November and December on its world tour.

An announcement on the band’s Facebook page did not disclose details about McVie’s cancer, only saying that the 67-year-old is “now scheduled to be in treatment for cancer during that period of time.”

Original members of the group — including Lindsey Buckingham, Mick Fleetwood, John McVie and Stevie Nicks — returned to touring last April after a three-year break from the road. (via CNN)