Jazz saxophonist Stan Getz will undergo major surgery at the Stanford Medical Center today for a large growth in his chest, the musician said. Getz, 60, who is a Stanford University artist-in-residence, said he had been aware of the growth for six months. "I don't think God is finished with me yet," he said in announcing the scheduled operation. "He wants me here on Earth another 20 years, and I'm all for it." Getz has been described as one of the most melodic and creative innovators on the tenor sax.