Predictive Factors for Acromegaly Remission after Transsphenoidal Surgery in a Portuguese tertiary care center

A. Maia*^a (Dr), C. Cidade Rodrigues^b (Dr), D. Borges Duarte^a (Dr), I. Ribeiro^c (Dr), C. Amaral^a (Dr)

^a Serviço de Endocrinologia, Diabetes e Metabolismo, Centro Hospitalar Universitário do Porto, Porto, PORTUGAL ; ^b Serviço de Endocrinologia, Diabetes e Metabolismo, Centro Hospitalar Tâmega e Sousa, Penafiel, PORTUGAL ; ^c Serviço de Neurocirurgia, Centro Hospitalar Universitário do Porto, Porto, PORTUGAL

* arianamaia@hotmail.com

Introduction: Acromegaly is a rare progressive endocrine disease resulting from increased release of growth hormone (GH) and insulin-like growth factor I (IGF1), in most cases due a GH-secreting pituitary tumour. Transsphenoidal surgery (TSS) is considered the first line treatment, being effective in ~75% of pituitary microadenomas with much lower remission rate for invasive macroadenomas (44.5% for suprasellar tumours, 33% for suprasellar tumours with visual compromise and 41.5% for tumours with parasellar and/or sphenoidal expansion). Our study aims to evaluate predictive factors for disease control in acromegaly patients submitted to TSS in our center.

Methods: Retrospective observational study. Clinical records of patients diagnosed with acromegaly who undergone TSS at our center between 1976 and 2021 were reviewed. Remission criteria was defined based on IGF-1 levels ≤ 1.3 × ULN (upper limit of normal) and random GH<1 µg/L/nadir GH after OGTT<0.4 µg/L, with a minimum follow-up period of 12 months after surgery approach. General patient characteristics, biochemical profile and imaging tests were retrospectively assessed and related to remission achievement. IGF-1 index was calculated by dividing IGF-1 levels by age and gender-adjusted upper limit of normal (ULN).

Results: Seventy-eight patients were included, with a mean age at diagnosis of 46.4±12.4 years and 53.8% being female. Surgical remission was achieved in 36 patients (46.2%). Most patients had pituitary macroadenomas (n=73, 93%). There were no statistically differences in age at diagnosis or sex in remission/non-remission group. Median pre-operative random GH, mean IGF-1 index and tumour size were statistically higher in non-remission group (12.6 vs. 5.2 ug/dL, p=0.024, 3.0 vs 2.3, p=0.021 and 23.7 vs 15.1 mm, p=0.001). Lateral invasion of cavernous sinus, but not optic chiasm invasion, was statistically more prevalent in the group that did not achieve post-surgical remission (p=0.03).

Discussion: Our study reinforces the unsatisfactory rates of acromegaly remission achieved after surgical intervention in patients with larger tumours (macroadenomas), with slightly higher remission rates in our center than those reported in the medical literature, supporting medical therapy role as a first/second line adjuvant. Higher pre-operative random GH, IGF-1 index, tumour size and cavernous sinus invasion were predictive factors for non-remission.

The author has declared no conflict of interest.