Passage: West died in Los Angeles, California, on June 9, 2017, following a brief battle with leukemia. After his death, West's former Batman co-star and longtime friend, Burt Ward, released a statement; "This is a terribly unexpected loss of my lifelong friend, I will forever miss him. There are several fine actors who have portrayed Batman in films. In my eyes, there was only one real Batman that is and always will be Adam West. He was truly the Bright Knight." Batman: The Animated Series actor Kevin Conroy (who performed alongside West in the episode "Beware the Gray Ghost") said "Adam West was an incredibly good, generous actor. Loved working with him as Gray Ghost. A true gentleman".On June 15, 2017, Los Angeles projected the Bat-Signal on City Hall as a tribute to West, and Walla Walla shone the bat-signal on the Whitman Tower.West pre-recorded five more episodes as Mayor Adam West released posthumously as part of Family Guy's sixteenth season. He also recorded the 11th episode of Powerless, which never aired due to the show's cancellation. NBC aired the episode online after West's death.West's last public appearances were from March to April 2017 at the SouthCoast Comic Con & Collectibles Extravaganza in Hanover, Massachusetts, where he was the guest of honor, Fan Expo Dallas, and the second annual Silicon Valley Comic Con.

Question: What disease caused the unfortunate passing of West?
leukemia