Endocrine Abstracts

Context: Immediate and sustained cure of acromegaly can only be achieved by surgery, however, most growth hormone (GH) producing adenomas are macroadenomas (≥ 10 mm) at diagnosis, with reported surgical cure rates of approximately 50% compared to microadenomas (<10 mm) with an expected higher cure rate (around 80%). Further, long-term data on remission rates after surgery are sparse.

Aim: Estimate short- and long-term surgical remission rates of patients with acromegaly and identify potentially predictive factors for long-term remission.

Methods: Patients who underwent surgery for a GH-producing pituitary adenoma between 2005-2020 were included from the local pituitary registry (n=178). Disease activity (GH and insulin-like growth factor 1, IGF-1), medical treatment, radiotherapy and reoperation were recorded at the short-term (one year postoperatively) and long-term (five year postoperatively) visit. Remission status was defined as IGF-1 ≤ 1.2 x upper limit of normal, without any additional surgical, radiation or pharmacological treatment for acromegaly. Baseline characteristics potentially predicting outcome (age, sex, GH and IGF-1 levels, tumor size (maximal diameter) and first treatment modality (preoperative with somatostatin analogues vs. direct surgery), were evaluated by multivariate regression models.

Results: Median age at diagnosis was 49 (IQR: 38-59) years, 46% were women. At diagnosis, 76% had macroadenomas and 24% microadenomas. Overall surgical remission rate at short-term was 54% and at long-term 41%. At short-term, 62% of patients with microadenomas and 52% with macroadenomas, obtained surgical remission. In patients who obtained persistent remission long-term, the remission rate was 58% for microadenomas and 37% for macroadenomas, with a trend towards higher remission rate in microadenomas (P = 0.058). In patients diagnosed in period 2005-2009, 2010-2013 and 2014-2020, the remission rates were 30%, 61% and 31%, respectively, at the long-term visit. Age, sex, GH and IGF-1 levels, tumor size and first treatment modality did not predict remission at long-term.

Conclusions: In unselected patients with acromegaly, the long-term remission rate after surgery was lower than expected and lower than the short-term outcomes. Our short-term outcomes are comparable to results of previous studies.