There is no evidence that Zak Bagans from Ghost Adventures has cancer. He has made comments about cancer in reference to a fan, Lauren Skillman, that died in November 2011.
It looks like season seven of Ghost Adventures is on the way, with reports of the crew filming scenes in locations such as Ben Lomond, California. They stopped nearby to visit locations from the 1987 vampire cult classic The Lost Boys.
Zak Bagans created the show Ghost Adventures with Nick Groff, it premiered in 2008. They travel the spooky back-roads researching reports of paranormal activity.