Phil Lesh, the bassist and founding member of the psychedelic jam band Grateful Dead, has been diagnosed with bladder cancer, the Associated Press reported. Lesh announced his diagnosis along the cancellation of two upcoming concerts with his group, Phil Lesh and Friends, via the Terrapin Crossroads Facebook page, his California restaurant and music venue.

"I was diagnosed with bladder cancer in early October, and have spent the last few weeks at the Mayo Clinic in Scottsdale doing tests and eventually surgery to remove the tumors," Lesh wrote in his Facebook post. "I am very fortunate to have the pathology reports show that the tumors are all non aggressive, and that there is no indication that they have spread."

Due to his surgery, Lesh will need two weeks to recover from his surgery, after which he will be able to return to his normal activities.

The Phil Lesh and Friends concerts, which were originally scheduled for Oct. 24 and 25 at the Terrapin Crossroads in San Rafael, Calif. and featured Black Crowes guitarist Chris Robinson, will be rescheduled, and ticket refund information will be available soon.

"Keep a lookout for a free Grate Room show before I leave for the East Coast shows," Lesh wrote. "I also plan to pop in and jam in the bar before we leave, so I hope to see you there at Terrapin."

As planned, the group is set to take up a six-date residency at the Capitol Theatre in Port Chester, N.Y., starting on Oct. 30, according to Rolling Stone.

See Lesh's full Facebook post below.