The group's co-founder has issued a statement revealing he won't be able to join his bandmates for their March and April (17) dates with Journey.

"I will soon be starting a new medical chemotherapy procedure, under which I will not be able to fly," he writes. "While I am naturally disappointed to miss the beginning of what I know will be an historic Asia tour, I am intending to return to the stage with Asia later in 2017.

"I know this decision will be in the best interests of my health and our fans in the long run."

Yes star Billy Sherwood will fill in for Wetton. Sherwood, who became a permanent member of Yes after Chris Squire lost his cancer battle last year (16), produced Wetton's solo album Raised in Captivity.

Asia will still perform without Wetton on the Yes-hosted Cruise to the Edge, which sets sail on 11 February (17).