SSTRs expression and tumor invasiveness in TSH-secreting adenomas and correlation analysis： a series of reports

Abstract:

Objective The postoperative remission rate of thyroid-stimulating hormone（TSH）-secreting pituitary adenoma（TSHoma） varies greatly among different studies. This study was intended to preliminarily explore the correlation between the expression of somatostatin receptors（SSTRs） and the morphological characteristics，tumor invasiveness，and prognosis of TSHoma.Methods This study retrospectively analyzed the clinical data of 10 patients who were diagnosed with TSHoma in the Second Affiliated Hospital of Army Medical University from October 2015 to April 2019，and nine of them underwent transsphenoidal or transcranial pituitary tumor resection. By reviewing magnetic resonance imaging images，a detailed assessment of tumor volume，invasiveness，and T2 weighted signal intensity in key regions of interest（ROIs） was conducted. Cavernous sinus invasiveness，sphenoid sinus invasion，suprasellar expansion were scored，and their cumulative score was calculated. In addition，the pituitary tissue slices of patients were immunohistochemically stained with SSTRs and scored using the semi-quantitative immune scoring method. According to the median score，patients were divided into high score group（HSG）（≥median） and low score group （LSG）（<median），and the differences in clinical data between the two groups were evaluated.Results The median age of 10 patients with TSHoma was 32.5 years，and the male-to-female ratio was 3∶2. All of them had macroadenomas，with aggressive growth to the suprasellar，parasellar，and cavernous sinus and varied volumes（0.50-93.20 mL）. The SSTRs staining score of TSHoma showed the following trend：SSTR2>SSTR5=SSTR3>SSTR1. The further analysis showed that the TSH level，tumor volume，Knosp grade，and invasion score in the HSG of SSTR2 were higher than those in the LSG，while the remission rate was lower than that in the LSG. On the contrary，the thyroid hormone level，TSH level，tumor volume，Knosp grade，and cavernous sinus invasion score in the HSG of SSTR5/SSTR2 ratio were lower than those in the LSG，and the remission rate was higher than that in the LSG. Unfortunately，the invasiveness degree of TSHoma was not correlated with tumor volume，thyroid hormone level，TSH level，and signal intensity in the ROI.Conclusion The expression level of SSTR2，especially the SSTR5/SSTR2 ratio，is correlated with invasiveness and biochemical levels，which may affect the prognosis after surgery.