Long-term control of acromegaly after pituitary surgery in South-Eastern Norway.

Purpose: Sustained cure of acromegaly can only be achieved by surgery. Most growth hormone (GH) secreting pituitary adenomas are macroadenomas (≥ 10 mm) at diagnosis, with reported surgical cure rates of approximately 50%. Long-term data on disease control rates after surgery are limited. Our aim was to estimate short- and long-term rates of biochemical control after pituitary surgery in acromegaly and identify predictive factors.

Methods: Patients operated for GH-secreting pituitary adenomas between 2005-2020 were included from the local pituitary registry (n = 178). Disease activity and treatment data were recorded at one-year (short-term) and five-year (long-term) postoperative follow-up. Biochemical control was defined as insulin-like growth factor 1 (IGF-1) ≤ 1.2 × upper limit of normal value. Multivariate regression models were used to identify factors potentially predicting biochemical control.

Results: A total of 178 patients with acromegaly (median age at diagnosis 49 (IQR: 38-59) years, 46% women) were operated for a pituitary adenoma. Biochemical control was achieved by surgery in 53% at short-term and 41% at long-term follow-up, without additional treatment for acromegaly. Biochemical control rates by surgery were of same magnitude in paired samples (45% vs. 41%, p = 0.213) for short- and long-term follow-up, respectively. At short-term, 62% of patients with microadenomas and 51% with macroadenomas, achieved biochemical control. At long-term, the biochemical control rate was 58% for microadenomas and 37% for macroadenomas (p = 0.058). With adjunctive treatment, 82% achieved biochemical control at long-term. Baseline IGF-1 levels significantly predicted biochemical control by surgery at short-term (OR: 0.98 (95% CI: 0.96-0.99), p = 0.011), but not at long-term (OR: 0.76 (95% CI: 0.57-1.00), p = 0.053).

Conclusion: In unselected patients with acromegaly, the long-term biochemical control rate remains modest. Our findings indicate a need to identify patients at an earlier stage and improve therapeutic methods and surgical outcomes.