The correlation between tumor shrinkage and biochemical response was also assessed; a positive relationship between tumor shrinkage and the achievement of “safe” GH levels was observed: in studies where higher rates (>75%) of “safe” GH levels were observed, more patients experienced tumor shrinkage compared with those studies in which “safe” GH control was less frequent (<25%) (OR: 5.0; 95% CI 1.50–16.63; Table 4); a positive correlation between tumor shrinkage and the attainment of normal IGF-I level was also observed [Table 4]. This evidence concerns the gene IGF1 and neoplasm.