GH1 and neoplasm: Although Buchfelder & Schlaffer18 reported a 74% success rate in achieving the GH/IGF-1 level control parameters, the stricter current parameters 6,7 led Evran et al. 19 and Sarkar et al. 20 to report success rates of 20-50% depending on the size of the tumor, the presence and degree of cavernous sinus invasion, the surgical technique employed and the surgeon's skill.