The official message, via the band's website:
Upon the completion of Nine Types of Light, Gerard was diagnosed with lung cancer. As a result, he has been undergoing treatment and will be unable to participate in the upcoming tour. Gerard is fortunate enough to have health insurance and is receiving excellent medical care. Already we have seen dramatic results. Combine that with Gerard's legendarily willful disposition and it might just be cancer that has the problem. We appreciate your concern and support for Gerard and his family.
All tour dates, and the April 12 release date for Nine Types of Light, are staying the same. The band's site also has made a new song, "Caffeinated Consciousness," available.