Diagnostic, therapeutic, and prognostic characteristics of patients with acromegaly according to tumor size at diagnosis.

Purpose: To evaluate clinical, laboratory, radiological, therapeutic, and prognostic characteristics of patients with acromegaly according to the size of the growth hormone (GH)-secreting pituitary adenoma at diagnosis.

Methods: Observational, retrospective, single-center study of patients with acromegaly followed at a tertiary center. Data were collected regarding clinical presentation, characteristics of the adenoma in the magnetic resonance imaging, GH and IGF-1 levels, and disease control after surgery or adjuvant treatment (normal IGF-1 levels). Patients were divided according to the adenoma size at diagnosis in: group I < 10 mm; II 10-19 mm; III 20-29 mm; IV 30-39 mm; and V ≥ 40 mm. Comparisons were made between the groups, and correlations of tumor size with disease parameters, ROC curves, and logistic regression analyses were performed to investigate tumor size and confounding factors that could impact the outcomes.

Results: 117 patients were studied [59 women, age at diagnosis 43 ± 13 years; group I = 11 patients (9%); group II 54 (46%); group III 34 (29%); group IV 10 (9%); group V 8 (7%)]. Hypopituitarism, cavernous sinus invasion, GH levels, and use of somatostatin receptor ligands had their prevalence increased according to the adenoma size. Age showed a negative correlation with tumor size. A tumor diameter around 20 mm was the best predictor for the presence of hypopituitarism, invasiveness, need of adjuvant therapies, and poorer disease control.

Conclusion: Adenomas < 20 mm showed lower morbidity and better therapeutic response in acromegaly, while those ≥ 20 mm had similar clinical, therapeutic, and prognostic behavior.