KISS recently re-launched its farewell trek.
Frehley said, "I'm on good terms with Paul and Gene,"
The diagnosis comes less than a week after his bandmate Paul Stanley's.
The band issued a statement confirming the diagnosis after the PA venue tweeted that the show on Thursday night was being rescheduled.
Stanley says Eric Carr turned KISS onto Metallica with the Black album.
Stanley was asked why fans are attached to a reunion of the band's original lineup.
"KISS is bigger than any member", he said.
"Shout It Out Loud" recently landed at Netflix.
The KISS frontman has once again said that it's still possible that original members could play a part in their last tour.
The two-part documentary event is part of the festival's 2021 TV lineup.