In the COMS trial of preoperative radiation, patients with large tumors were randomized to enucleation alone or to enucleation preceded by 20 Gy of external beam radiation. The two randomly assigned groups of patients were followed for at least five years or until death and have been compared on the basis of length of remaining life and other outcomes. Enrollment in this trial was completed in December 1994, with 1,003 patients enrolled. Clinical follow-up of all patients in this trial ended in July 2000.