Endocrine Abstracts

Background: Corticotroph tumours are a heterogenous group of pituitary neuroendocrine tumours (PitNETs) in terms of their histological type, clinical presentation and tumour behaviour. These tumours are overrepresented in recurrent PitNETs and pose an important clinical and therapeutic challenge¹. Although risk factors such as radiological invasion and elevated proliferative markers have been identified for PitNET recurrence, an improvement in proposed prognostic models is necessary to optimise management and monitoring of corticotroph tumour after surgical resection². We compared recurrent and non-recurrent corticotroph tumours to assess differences in clinical and histological parameters.

Methods: 51 consecutive corticotroph PitNETs resected from 2011 to 2018 and archived at Westmead Hospital were reviewed in a retrospective study. All tumours were characterised using transcription factor and hormonal immunohistochemistry. Corticotroph PitNETs were identified by positive TPIT expression. Clinical, radiological and histological characteristics of recurrent tumours were compared with cases without recurrence. 5 cases were excluded due to lack of adequate follow up data.

Results: Twelve cases (26%) had radiological or biochemical recurrence with mean time to detection of 45 months (range 12-144). Proportion of sparsely granulated subtype was similar in both groups(75% vs 76.5%, P=0.69). There was no significant difference in the proportion of silent and functioning corticotroph tumours between the two groups (58.3% vs 67.6% silent and 41.7% vs 32.4% functioning, P=0.72). Maximum tumour diameter at presentation was greater for tumours that later recurred (25.4 vs 17.2mm, P=0.046). Radiological or histological invasion was more frequent in recurrent tumours, though not statistically significant (42.9% vs 30%, P=0.67). Recurrent tumours were more likely to have a visible residual tumour after first resection (66.7% vs 20.6%, P=0.01). Presence of tumour remnant after surgery was associated with recurrence (OR 7.42, 95% CI 1.72 to 32.05, P=0.0072). The 12 recurrent tumours required a total of 24 separate interventions. Of these, 66.7% were repeat surgery, 16.7% radiotherapy, 12.5% medical therapy and 9.5% bilateral adrenalectomy. 33.3% of recurrent tumours expressed SSTR5.

Conclusion: Persistent tumour remnant after surgery may be an important predictor of corticotroph PitNET recurrence requiring further therapeutic intervention. Silent corticotroph tumours or sparsely granulated subtype did not predict recurrence in our study.

References: 1. Guaraldi F, Zoli M, Righi A, et al. A practical algorithm to predict postsurgical recurrence and progression of pituitary neuroendocrine tumours (PitNET)s. Clin Endocrinol (Oxf). 2020;93(1):36-43. 2. Raverot G, Dantony E, Beauvy J, et al. Risk of Recurrence in Pituitary Neuroendocrine Tumors: A Prospective Study Using a Five-Tiered Classification. J Clin Endocrinol Metab. 2017;102(9):3368-3374.