Preoperative and long-term efficacy and safety of lanreotide autogel in patients with thyrotropin-secreting pituitary adenoma: a multicenter, single-arm, phase 3 study in Japan

The effect of preoperative short-term octreotide treatment to surgery in thyrotropin-secreting pituitary adenomas: a retrospective cohort study

BACKGROUND

To prevent thyroid storm and ensure surgical safety, it is imperative to regulate excessive thyroid hormone levels in patients with thyrotropin-secreting pituitary adenomas (TSHoma) prior to surgery. Somatostatin analogues (SSAs), such as octreotide, have showed efficacy in shrinking tumors, which may facilitate surgical resection. This retrospective study aimed to investigate the effect of shortterm preoperative octreotide treatment on the surgical outcome of TSHoma.

METHODS

A total of 65 TSHoma patients from January 2010 to July 2019 were included in the study. Of these,41 patients received short-term preoperative octreotide (Sandostatin, intermittent subcutaneous injection) treatment and all patients subsequently underwent surgery. The following data were recorded: clinical manifestations, laboratory examinations, sellar region MRI, postoperative pathological and electron microscopy data, intraoperative situation, and follow-up (> 3 months) regarding hormone levels and tumor recurrence.

RESULTS

There was no significant difference in the consistency and blood supply of the tumor between patients who received short-term preoperative octreotide treatment and those who did not. Additionally, preoperative short-term octreotide treatment (median of 10 days with a range of 6-18 days) did not significantly improve the rates of gross total resection (GTR) or biochemical remission. Moreover, electron microscopy revealed subcellular level impairments and cell apoptotic in the octreotide treated TSHoma specimens.

CONCLUSION

Preoperative octreotide treatment for the purpose of reducing excessive thyroid hormones may not enhance surgical outcomes, and the duration of octreotide treatment needs to be extended to fully benefit from the tumor-shrinking effects of SSAs.

Clinical Biology of the Pituitary Adenoma

All endocrine glands are susceptible to neoplastic growth, yet the health consequences of these neoplasms differ between endocrine tissues. Pituitary neoplasms are highly prevalent and overwhelmingly benign, exhibiting a spectrum of diverse behaviors and impact on health. To understand the clinical biology of these common yet often innocuous neoplasms, we review pituitary physiology and adenoma epidemiology, pathophysiology, behavior, and clinical consequences. The anterior pituitary develops in response to a range of complex brain signals integrating with intrinsic ectodermal cell transcriptional events that together determine gland growth, cell type differentiation, and hormonal production, in turn maintaining optimal endocrine health. Pituitary adenomas occur in 10% of the population; however, the overwhelming majority remain harmless during life. Triggered by somatic or germline mutations, disease-causing adenomas manifest pathogenic mechanisms that disrupt intrapituitary signaling to promote benign cell proliferation associated with chromosomal instability. Cellular senescence acts as a mechanistic buffer protecting against malignant transformation, an extremely rare event. It is estimated that fewer than one-thousandth of all pituitary adenomas cause clinically significant disease. Adenomas variably and adversely affect morbidity and mortality depending on cell type, hormone secretory activity, and growth behavior. For most clinically apparent adenomas, multimodal therapy controlling hormone secretion and adenoma growth lead to improved quality of life and normalized mortality. The clinical biology of pituitary adenomas, and particularly their benign nature, stands in marked contrast to other tumors of the endocrine system, such as thyroid and neuroendocrine tumors.

An Update on the Pathophysiology and Diagnosis of Inappropriate Secretion of Thyroid-Stimulating Hormone

Inappropriate secretion of thyroid-stimulating hormone (IST), also known as central hyperthyroidism, is a clinical condition characterized by elevated free thyroxine and triiodothyronine concentrations concurrent with detectable thyroid-stimulating hormone (TSH) concentrations. Similarly, the term syndrome of IST (SITSH) is widely used in Japan to refer to a closely related condition; however, unlike that for IST, an elevated serum free triiodothyronine concentration is not a requisite criterion for SITSH diagnosis. IST or SITSH is an important indicator of resistance to thyroid hormone β (RTHβ) caused by germline mutations in genes encoding thyroid hormone receptor β (TRβ) and TSH-secreting pituitary adenoma. Recent evidence has accumulated for several conditions associated with IST, including RTH without mutations in the TRβ gene (non-TR-RTH), the phenomenon of hysteresis involving the hypothalamus-pituitary-thyroid axis (HPT-axis), methodological interference, and Cushing’s syndrome after surgical resection. However, little information is available on the systematic pathophysiological aspects of IST in previous review articles. This report presents an overview of the recent advances in our understanding of the etiological aspects of IST that are relevant for diagnosis and treatment. Moreover, the report focuses on the potential mechanism of IST caused by hysteresis in the HPT-axis (lagging TSH recovery) in terms of epigenetic regulation.