The implication of somatotroph adenoma phenotype to somatostatin analog responsiveness in acromegaly.
BACKGROUND
Persistently elevated GH and IGF-I levels are associated with increased mortality. Their response to somatostatin analogs (SSA) is variable.


OBJECTIVE
The objective of this study was to examine the significance of somatotroph adenoma type on response to SSA.


METHODS
This study was a retrospective examination of postoperatively treated acromegalic patients with the SSA octreotide.


METHODS
The study was performed at a university-affiliated tertiary care center.


METHODS
Forty patients with acromegaly were studied.


METHODS
Normalization of IGF-I levels and GH responses were the main outcome measures.


RESULTS
Univariate analysis revealed that responders were more likely to have densely granulated somatotroph adenomas (80% vs. 43.8%; P = 0.024), to be older (51.3 vs. 38.2 yr; P < 0.003), to have smaller tumors (stage < or =3; 78.6% vs. 35.7%; P = 0.022), to have lower baseline IGF-I (453 vs. 716 microg/liter; P < 0.001) and GH levels (2.7 vs. 7.8 microg/liter; P < 0.05), and to require a lower maximum dose of SSA (24 vs. 31 mg every 4 wk; P = 0.013). Multivariate analysis confirmed that a densely granulated adenoma was the strongest predictor of complete response [adjusted odds ratio (OR), 58.41; 95% confidence interval (CI), 1.24-1000.00; P = 0.04] compared with other covariates, including older age at time of diagnosis (OR, 1.15/yr; 95% CI, 1.01-1.31; P = 0.03), and tumor stage of 3 or less (OR, 29.77; 95% CI, 1.01-885.45; P < 0.05).


CONCLUSIONS
Somatotroph tumor type represents a strong clinical predictor of response to SSA treatment and will help to identify patients who warrant more vigilant management of their disease.
Bhayana
Shelly
S
Department of Medicine, Mount Sinai Hospital, 600 University Avenue, Room 437, Toronto, Ontario, Canada M5G 1X5.
Booth
Gillian L
GL
Asa
Sylvia L
SL
Kovacs
Kalman
K
Ezzat
Shereen
S
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; D015999:Multivariate Analysis; D015282:Octreotide / Q000627:therapeutic use*; D010641:Phenotype; D010911:Pituitary Neoplasms / Q000097:blood / Q000188:drug therapy*; D012189:Retrospective Studies
D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D015282:Octreotide