Hagman declined to specify what kind of cancer he's contracted, but said it's "a very common and treatable form." He plans to continue working on a new reboot of "Dallas" for TNT, which begins production Monday.

The new "Dallas" focuses on the Ewing offspring as they clash over the future of the family dynasty. The original prime-time soap opera aired on CBS from 1978 to 1991. Hagman underwent a liver transplant in the mid-1990s.

Said Hagman: "As we all know, you can't keep J.R. down!"