title: Growth hormone-secreting tumor shrinkage after 3 months of octreotide-long-acting release therapy predicts the response at 12 months.
abstract: OBJECTIVE
  The objective of the study was to evaluate whether tumor shrinkage or GH and IGF-I levels achieved after 3 months predicted tumor shrinkage after 12 months of octreotide-long-acting release (LAR) treatment.
  
  
  METHODS
  Patients included 67 patients with de novo acromegaly (33 women, 34 men; aged 20-82 yr) receiving LAR at a dose of 20 mg every 28 d for 3 months. Final LAR dose was 10 mg every 28 d in 4, 30 mg every 28 d in 39, 20 mg every 28 d in 24 patients.
  
  
  METHODS
  The design of the study was analytical, observational, open, and retrospective.
  
  
  METHODS
  Percent change in GH and IGF-I levels and tumor volume after 3 and 12 months of therapy was measured. Stepwise regression and receiving-operator characteristics analysis were used to calculate the optimal cutoff to predict 12 months tumor shrinkage at 12 months.
  
  
  RESULTS
  The percent tumor shrinkage after 12 months was significantly correlated with GH, IGF-I, and tumor volume at 3 months and with the dose of LAR administered between 3 and 12 months. There was no correlation with gender, age, baseline GH levels and tumor volume. In a stepwise regression analysis, percent tumor shrinkage after 3 months was the best predictor of tumor shrinkage after 12 months (t = 5.92; P < 0.0001), followed by GH levels after 3 months (t = 2.86; P = 0.0056). To predict 50% or greater tumor shrinkage after 12 months, the best cutoff point of tumor shrinkage at 3 months was 22.1% [sensitivity (95% confidence interval) = 85.5% (71.2-95.4); specificity = 83.3% (65.3-94.3)], whereas that of GH levels after 3 months was 7.8 microg/liter [sensitivity = 70.3% (53.0-84.1); specificity = 93.3% (79.0-99.0)].
  
  
  CONCLUSIONS
  Tumor shrinkage achieved after 3 months of LAR treatment at 20 mg/28 d predicted tumor shrinkage at 12 months, provided that dosages were changed according to individual patients requirement.
authors.affiliation: Department of Molecular and Clinical Endocrinology and Oncology, Federico II University of Naples, via S. Pansini 5, 80131 Naples, Italy. colao@unina.it
authors.forename: Annamaria
authors.initials: A
authors.lastname: Colao
authors.forename: Rosario
authors.initials: R
authors.lastname: Pivonello
authors.forename: Renata S
authors.initials: RS
authors.lastname: Auriemma
authors.forename: Mariano
authors.initials: M
authors.lastname: Galdiero
authors.forename: Silvia
authors.initials: S
authors.lastname: Savastano
authors.forename: Ludovica F S
authors.initials: LF
authors.lastname: Grasso
authors.forename: Gaetano
authors.initials: G
authors.lastname: Lombardi
mesh_terms: D000172:Acromegaly / Q000188:drug therapy / Q000209:etiology / Q000473:pathology; D000236:Adenoma / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage; D003692:Delayed-Action Preparations; D005260:Female; D005500:Follow-Up Studies; D049912:Growth Hormone-Secreting Pituitary Adenoma / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000008:administration & dosage*; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D047368:Tumor Burden / Q000187:drug effects*
chemical_list: D018931:Antineoplastic Agents, Hormonal; D003692:Delayed-Action Preparations; D015282:Octreotide