Background: Neurosurgery is treatment of choice in patients with GH-secreting pituitary adenoma. However, in about 50% of cases surgery is ineffective or contraindicated. Long-acting somatostatin analogues are possible, although expensive therapeutic alternative. Generally, 6070% of patients with active disease responds to such medical treatment.
Aim: Aim of this study was to identify factors influencing medical treatment outcome and to determine if testing injection of 100 mcg octreotide s.c. (SHort Octreotide Test SHOT) may be used as predictive tool.
Material: Material consisted of 137 patients (88 F and 49 M) aged 1783 years (mean 49.6) with active acromegaly, treated 20012005 in one center. Neurosurgery was primary therapy in 48 cases.
Methods: SHOT: GH assessed in 30 min intervals during 2 h acute 100 mcg octreotide s.c. test. Treatment initiation: GH and IGF-1 concentrations were determined at 1, 3, 7, 14 and the 28 day following test dose 20 mg of OCT-LAR i.m. Prolonged treatment: GH and IGF-1 assessments were performed quarterly during 25 years of medical treatment. Imaging (MR) was performed yearly and KNOSP scale was assessed.
Results: Significant reduction of GH concentration (by more than 75%) was achieved in 48 out of 137 cases (35%) SHOT suppressed GH below 2 ng/ml, but in 93 (68%) GH reduction by more than 75% was achieved. Administration of the first OCT-LAR dose suppressed GH below 2 ng/ml in 44 patients (32%) and in 93 (68%) by more than 75%, whereas the IGF-1 levels dropped to agesex reference range in 39 cases (28%). Most pronounced reduction of GH level (mean drop from 26.2 to 10.8 ng/ml) was registered at the 14th day following the OCT-LAR. During prolonged treatment, GH and IGF-1 levels decreased slowly during first year, and then remained stable (mean 8.3 ng/ml S.D. 5.7 and 497 ng/ml S.D. 312 for GH and IGF-1, respectively). IGF-1 normalization were achieved in 76 (55%). Reduction of GH levels in SHOT tightly correlated with the GH level during long-term treatment (R=0.68, P<0.001). Assessment of GH and IGF-1 during first month of therapy has no additional value. Reduction of GH below 2 ng/ml defines cohort of most probable IGF-1 normalization (sensitivity (sen.) 96% and specificity (spe.) 95.5%), whereas by >75% precisely predicts good outcome of long term therapy (sen. 97% and spe. 70%). Other, independent factors of good outcome is symptoms duration <10 years (sen. 72% spe. 65% and KNOSP grade <3 sen. 63% spe. 48%).
Conclusions: SHOT is effective in identification of cohort with favourable prognosis of pharmacological treatment efficacy.
03 - 07 May 2008
European Society of Endocrinology