Evaluation of plasma insulin-like growth factor binding protein-2 as a marker for adrenocortical tumors

Objective: Recent studies have pointed to the role of the IGF system in the pathogenesis of adrenocortical tumors, and it was shown recently that mali gnant adrenocortical tumors exhibit a high insulin-like growth factor bindi ng protein (IGFBP)-2 content, Circulating markers specific for adrenocortic al carcinoma are needed and the aim of this study was to evaluate plasma IG FBP-2, as a marker for these malignant turners. Methods: Plasma IGFBP-2 was determined in 51 patients referred to our insti tutions for adrenocortical tumors. Fifteen patients were in complete remiss ion (group 1). eight patients had preoperative localized tumors (group 2) a nd 28 patients had metastatic tumors (group 3). Thirty-six healthy voluntee rs constituted a control group. Results: There was no significant difference in plasma IGFBP-2 concentratio n between healthy controls and patients with complete remission or localize d tumors, In contrast, patients with metastatic disease had significantly h igher IGFBP-2 plasma levels than the control group (P < 0.001). IGFBP-2 lev els in patients with metastatic disease were inversely correlated with surv ival (R-2 = 0.308; P = 0.0026). In patients with localized tumors, there wa s no correlation between plasma IGFBP-2 concentration and tumor size or his tological features, Analysis of individual IGFBP-2 concentrations showed th at five patients (17.8%) with metastatic tumors had normal IGFBP-2, levels and two patients (13.3%) in complete remission had high plasma IGFBP-2 leve ls. The influence of nutrition, hormone secretion and treatment on IGFBP-2 levels was examined. Nutritional status was evaluated by determining IGF-I levels and was found to be normal in 16 patients (61.5%) with high IGFBP-2 levels, suggesting that malnutrition was not responsible for the high IGFBP -2 concentrations in these patients. IGFBP-2 levels did not differ signific antly according to tumor secretion or mitotane treatment. In a follow-up st udy, plasma IGFBP-2 concentration remained stable in patients with complete remission or stabilized disease and was a late marker of tumor progression in patients with progressive metastatic disease. Conclusions: These results indicate that plasma IGFBP-2 is elevated in pati ents with malignant adrenocortical tumors and that the major factor affecti ng IGFBP-2 levels in these patients is tumor stage, However plasma IGFBP-2, was less sensitive than expected for a tumor marker, which may limit its v alue in the diagnosis and follow-up of adrenocortical carcinoma.