Story highlights Phil Lesh is a founding member of the California band Grateful Dead

Bassist has had solo career for two decades

(CNN) Phil Lesh, who was bassist for the rock band Grateful Dead, canceled two concerts after revealing he has bladder cancer.

In a letter to fans posted Friday on the Facebook page for Terrapin Crossroads, his restaurant and concert venue in San Rafael, California, Lesh said he was diagnosed with bladder cancer earlier this month. He said he has spent the last few weeks at the Mayo Clinic in Scottsdale, Arizona, doing tests ahead of surgery to remove the tumors.

Lesh, 75, said his prognosis is positive.

"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," Lesh said. "So thanks to my local doctor Cliff Sewell, and the incredible team at the Mayo Clinic, all is well and I can return to normal activities in two weeks from my surgery."

Lesh is a founding member of the Grateful Dead, an American jam band that formed in the 1960s. The San Francisco group disbanded in the mid-1990s and Lesh went on to form his own music group Phil & Friends. At the time of his cancer announcement, his band was touring with Chris Robinson, a singer with the Black Crowes.

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