Background: To investigate the role of 99m Tc-labeled sestamibi (99m Tc-MIBI) retention level in the assessment of malignant potential of parathyroid lesions. Methods: Twenty patients with parathyroid carcinomas and forty controls with benign parathyroid lesions who underwent preoperatively 99m Tc-MIBI dual-phase planar and SPECT/CT imaging were retrospectively enrolled in this study. The mean and peak of retention index (RI mean and RI peak) were measured for evaluating the retention level of 99m Tc-MIBI in the parathyroid lesions. Diagnostic accuracies of RI for differentiating malignant parathyroid lesions from benign ones were assessed by receiver operating characteristic analyses (area under the curve; AUC). Results: RI peak (AUC =0.87, P<0.001) and RI mean (AUC =0.78, P<0.001) showed significant difference between the malignant and benign lesions. The diagnostic sensitivity, specificity, positive and negative predictive values, accuracy of RI peak were respectively 80.0%, 85.0%, 72.7%, 89.5% and 83.3% when its cutoff value was −19.03%. In addition, the level of serum parathyroid hormone (PTH) slightly correlated with RI peak (r=0.260, P=0.044) or RI mean (r=0.281, P=0.029). Conclusions: Parathyroid carcinomas have higher retention level of 99m Tc-MIBI than benign parathyroid lesions. RI peak may contribute to preoperative differential diagnosis of parathyroid carcinoma.

BackgroundWe assessed the association between microsatellite instability-high (MSI-H) and tumor response to neoadjuvant chemotherapy (NAC) as well as its prognostic relevance in patients with clinical stage III gastric cancer (cStage III GC).Materials and MethodsThe NAC + surgery and the control cohorts consisted of 177 and 513 cStage III GC patients, respectively. The clinical and pathological features were compared between patients with MSI-H [n=57 (8.3%)] and microsatellite stability or microsatellite instability-low (MSS/MSI-L) [n=633 (91.7%)]. Radiological and histological response to NAC were evaluated based on response evaluation criteria in solid tumors (RECIST) and tumor regression grade (TRG) systems, respectively. The log-rank test and Cox analysis were used to determine the survival associated with MSI status as well as tumor regression between the two groups in both NAC + surgery and the control cohorts.ResultsA statistically significant association was found between MSI-H and poor histological response to NAC (p=0.038). Significant survival priority of responders over poor-responders could only be observed in MSS/MSI-L but not in MSI-H tumors. However, patients with MSI-H had statistically significantly better survival compared to patients with MSS/MSI-L in both the NAC + surgery (hazard ratio=0.125, 95% CI, 0.017–0.897, p=0.037 ) and the control cohort (hazard ratio=0.479, 95% CI, 0.268–0.856, p=0.013).ConclusionMSI-H was associated with poorer regression and better survival after NAC for cStage III GC. TRG evaluation had prognostic significance in MSS/MSI-L but not in MSI-H. Further studies are needed to assess the value of NAC for cStage III GC patients with MSI-H phenotype.