Endocrine Abstracts

Background: Transsphenoidal surgery (TSS) is the primary treatment of choice in acromegaly. Previous research succeeded to some extent in predicting remission after TSS. However, it was based mainly on clinical and radiological data, lacking histopathological evaluation.

Objective: To produce a clinicopathological prediction model for remission after TSS for acromegaly, enabling clinicians to better inform patients on expected treatment outcome.

Design: Single-center study with retrospective data collection on patients with acromegaly in a large tertiary referral center in The Netherlands. Overall, 100 patients with acromegaly in whom TSS was performed as primary therapy between January 2000 and July 2019 were included.

Methods: Data were collected on sex, age, biochemistry (IGF1, GH nadir during OGTT, random GH) at diagnosis, 3 months to 1 year postoperatively and at last visit, use of preoperative medication, applied postoperative treatment (repeated surgery, radiotherapy and medical therapy), tumour subtype according to the WHO 2017 classification and proliferation markers (Ki-67, p53 and mitotic index). All available diagnostic and first postoperative MRI’s were reassessed by an experienced neuroradiologist and classified according to the Knosp classification. In addition, tumour volume (cm3), maximum tumour diameter (mm) and T2-weighted MRI signal were determined. Uni- and multivariate regression models were used to identify predictors of early biochemical remission (12 weeks to 1 year postoperatively) according to the consensus criteria and long-term remission (age- and sex-normalized IGF1, absence of postoperative treatment until last follow-up and absence of a tumour remnant on postoperative MRI).

Results: Median duration of follow-up was 11.8 years from diagnosis and 11.1 years from surgery. Forty-six (46.5%) patients were found to be in early biochemical remission, forty-one (42.7%) were in long-term remission. In univariate logistic regression larger tumour volume (odds ratio [OR] 0.86, P=0.023), larger maximum tumour diameter (OR 0.85, P<0.001), higher modified Knosp classification grade (OR 0.44, P<0.001), presence of cavernous sinus invasion (OR 0.054, P=0.006) and higher random GH at diagnosis (OR 0.98, P=0.008) were significantly associated with lower remission rates. In multivariate logistic regression, a simple model with only maximum tumour diameter as independent variable predicted best for both early biochemical remission (OR 0.85, 95% CI 0.78-0.93, P<0.001, sensitivity 78.9%, specificity 71.8%) and long-term remission (OR 0.75, 95% CI 0.66-0.86, P<0.001, sensitivity 79.4%, specificity 78.0%).

Conclusion: maximum tumour diameter is the best predictor for remission after TSS for acromegaly in this single center cohort.