GH1 and neoplasm: Rick et al. reported that compared to pure somatotroph tumors, tumors that stain for both GH and prolactin presented with significantly higher serum IGF-1 (803.6 vs. 480.0 μg/L) and prolactin (60.7 vs. 10 μg/L) levels, had a lower remission rate (32% vs. 80%) and the recurrence risk was higher (18.2% vs. 7%), although in their study, the mean tumor size was similar in both groups.