Predictors of tumor shrinkage after primary therapy with somatostatin analogs in acromegaly: a prospective study in 99 patients.
BACKGROUND
Primary treatment with depot octreotide and lanreotide induces tumor shrinkage in newly diagnosed patients with acromegaly.


OBJECTIVE
The objective of the study was to evaluate clinical predictors of tumor shrinkage.


METHODS
This was an analytical, observational, open, prospective study.


METHODS
The study included 99 patients: 13 with microadenoma and 86 with macroadenoma (25 enclosed, 32 extrasellar, 29 invasive).


METHODS
Age, gender, estimated disease duration, body mass index, GH and IGF-I levels, and tumor volume at diagnosis and after 12 months of treatment were measured. Percentage of GH, IGF-I, and tumor size changes from baseline were also analyzed. Tumor changes were scored as absent (+/- 0-25%), mild (+/- 25.1-50%), moderate (+/- 50.1-75%), or notable (75%).


METHODS
Sixty patients (60.6%) received depot octreotide im (20-30 mg every 28 d), and 39 patients (39.4%) received lanreotide im (60-90 mg every 28 d).


RESULTS
Basal tumor volume and maximal tumor diameter correlated with age, disease duration, and GH levels. After 12 months, GH levels were controlled (</=2.5 microg/liter) in 57.6%, IGF-I levels in 45.5%, and both in 42.4%. Shrinkage was absent in 22 patients (22.2%), mild in 31 (31.1%), moderate in 30 (30.3%), and notable in 14 patients (14.1%). Two patients (not responding to treatment) had a mild tumor increase (by 34 and 31.2%, respectively). Basal and posttreatment tumor volumes were highly correlated (r = 0.79, P < 0.0001). At the multistep regression analysis, the percent IGF-I decrease (t = 2.6; P = 0.011) was the best predictor of posttreatment tumor volume, followed by patients' age (t = 2.1; P = 0.042) and percent GH decrease (t = 2.0; P = 0.044).


CONCLUSIONS
Most patients with acromegaly (75.5%) had 25% or greater tumor shrinkage after 12 months of primary somatostatin analog therapy: significant increase of tumor mass occurred in only 2.1% of patients (uncontrolled during treatment). Best predictor of tumor shrinkage was posttreatment IGF-I.
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
Briganti
Francesco
F
Galdiero
Mariano
M
Tortora
Fabio
F
Caranci
Ferdinando
F
Cirillo
Sossio
S
Lombardi
Gaetano
G
D000172:Acromegaly / Q000097:blood / Q000188:drug therapy*; D000236:Adenoma / Q000097:blood / Q000188:drug therapy*; D000328:Adult; D000368:Aged; D005260:Female; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000627:therapeutic use*; D010456:Peptides, Cyclic / Q000627:therapeutic use*; D010911:Pituitary Neoplasms / Q000097:blood / Q000188:drug therapy*; D011446:Prospective Studies; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000627:therapeutic use
D010456:Peptides, Cyclic; C060347:lanreotide; D019382:Human Growth Hormone; D013004:Somatostatin; D007334:Insulin-Like Growth Factor I; D015282:Octreotide