Endocrine Abstracts

Introduction: Oestrogens and androgens modulate the effects of growth hormone (GH). Sex differences have been described in acromegaly, with conflicting results in different populations. Additionally, data on sex differences in tumour histopathology are scarce.

Aims: To analyse the influence of sex and menopause status in tumour characteristics and surgical outcomes in patients with acromegaly.

Materials and methods: Retrospective cohort study of patients with acromegaly submitted to transsphenoidal surgery, followed in a tertiary centre from 1988-2021. Postoperative biochemical remission was defined at ≥12 weeks by a normalization of insulin like growth factor-1 (IGF-1) and random GH <1ug/l or GH nadir <1ug/l after a 75-g oral glucose tolerance test. IGF-1 was presented as percent of upper limit of the normal value (%ULN). Differences in tumour size and invasiveness, hormone deficiencies, histopathology and surgical outcomes were compared between sex and pre/postmenopausal status at the time of diagnosis.

Results: We obtained a total of 65 patients: 44 women (12 postmenopausal), 21 men. Mean age at diagnosis in women was 48.1±12.1 vs 47.9±13.0 years in men (P=0.933), and mean IGF-1 was 296.3±126.9 vs 319.2±1221 %ULN (P=0.497). Pure somatotroph tumours accounted for 68.2% in women vs 71.4% in men, mixed somatotroph-lactotroph 25.0% vs 19.0%, plurihormonal PIT1+ 4.5% vs 9.5%, null cell 2.3% vs 0%. Somatotroph tumours were sparsely granulated in 83.3% of women and densely granulated in 75.0% of men (P=0.001). Postmenopausal women had less macroadenomas than premenopausal (47.1% vs 90.9%, P=0.004), lesser cavernous sinus invasion and suprasellar extension (16.6% vs 61.1%, P=0.016, and 30.8% vs 83.3%, P=0.003) and higher postoperative biochemical remission (52.6% vs 17.4%, P=0.016) and radiological remission at 1-year post-surgery (73.7% vs 27.3%, P=0.003), despite no differences in histopathology. Compared to women, men had a higher prevalence of hypogonadism at diagnosis (57.1% vs 22.7%, P=0.004) and lower rates of radiological remission (11.8% vs 47.6%, P=0.010). Tumour size was similar in men and premenopausal women (23.8 vs 26.0mm, P=0.546) and correlated inversely with age at diagnosis (r=-0.4, P=0.006). Men showed no significant differences regarding tumour invasiveness, postoperative biochemical remission or medical treatment response.

Conclusions: In our cohort men showed a higher prevalence of hypogonadism at diagnosis and lower radiological remission. Premenopausal women showed larger and more invasive tumours than postmenopausal, which may be due to younger age, but also to the oestrogen modulation of GH/IFG-1 axis. Differences in somatotroph tumour histopathology between sex may reflect a different impact of gonadal hormones in tumourigenesis.