Growth hormone-secreting tumor shrinkage after 3 months of octreotide-long-acting release therapy predicts the response at 12 months.
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.
Colao
Annamaria
A
Department of Molecular and Clinical Endocrinology and Oncology, Federico II University of Naples, via S. Pansini 5, 80131 Naples, Italy. colao@unina.it
Pivonello
Rosario
R
Auriemma
Renata S
RS
Galdiero
Mariano
M
Savastano
Silvia
S
Grasso
Ludovica F S
LF
Lombardi
Gaetano
G
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*
D018931:Antineoplastic Agents, Hormonal; D003692:Delayed-Action Preparations; D015282:Octreotide