Earlier this year, classic rock institution Heart ended a five-year hiatus, put in appearances on The Tonight Show and The Kelly Clarkson Show, and mounted their Royal Flush tour. In May, they finished that tour’s first leg with a show in Atlantic City, and they were scheduled to resume later this month with a Cleveland stadium show alongside Def Leppard and Journey. They were planning more of those stadium shows, along with headlining arena gigs with Cheap Trick. Yesterday, however, the band announced that lead singer Ann Wilson has been treated for cancer and that they’ll have to postpone those shows.