Metal legends Heaven And Hell have canceled their summer European tour, which was to include sets at the Bloodstock and Sonisphere festivals.The cancellation is due to frontman Ronnie James Dio's ongoing cancer treatment."We have to announce that all forthcoming Heaven And Hell European shows have been cancelled as sadly Ronnie isn't well enough to tour this summer," reads an official statement from the band. "We hope that everyone understands and want to thank fans and industry colleagues for their continuing support at this time."As previously reported, Dio was diagnosed with stomach cancer last November.