Punk rock group Green Day says it is canceling its U.S. club tour because of lead singer Billie Joe Armstrong\'s continuing treatment for substance abuse issues. The tour was to kick off in Seattle last month and wrap up in Tempe, Ariz., Dec. 10. All of those gigs have been canceled and Green Day said Monday it will postpone all scheduled appearances for January and February as well. Armstrong checked into a treatment facility to seek help for unspecified substance abuse problems following last month\'s iHeartRadio Music Festival during which the musician ranted onstage because he thought his group\'s set was cut short to make way for other acts. The band later said it had as much time as expected and apologized for Armstrong\'s behavior. Tickets for the canceled shows will be refunded at point of purchase, the band said, and new dates for the rescheduled concerts will be announced shortly. Previously purchased tickets will be honored on the new dates. \"Obviously, the timing for this isn\'t ideal, but Billie Joe\'s well-being is our main concern,\" bassist Mike Dirnt said in a statement posted on the band\'s website Monday. \"We are happy to say that Billie Joe is doing well, and we want to thank you all for the outpouring of support and well wishes that we have received, and we can\'t wait to see you all again soon.\" Green Day also announced it would move up the release date of its album \"Green Day ¡Tre!\" to Dec. 11 from its original date of Jan. 15. \"We feel bad we have to delay our tour, so, to make up for it, we want to give our fans the music earlier than we had planned,\" said drummer Tre Cool. \"If we couldn\'t be there to play it for you live, the least we could do was give you the next best thing.\"