The somatic Thr372Arg YY1 mutation is a relevant finding in female patients with sporadic insulinomas. The prevalence of this mutation in this Caucasian population is considerably lower compared to that of a recently described Asian cohort.

Calcitonin (CT), a tumor marker for medullary thyroid cancer (MTC), can be stimulated with pentagastrin or calcium. Because of the unavailability of pentagastrin, basal CT measurement is frequently used for the preoperative diagnosis of MTC. The aim of the study was to define basal serum calcitonin (bCT) cut-off thresholds for diagnosing MTC. Within a retrospective analysis, 114 patients (51 males) were included fulfilling the criteria of an increased preoperative bCT level (>10 pg/ml) and the criteria of an available postoperative histology analysis. Based on a ROC plot analysis, the cut-off values for the diagnosis of MTC vs. non-malignancy (C cell hyperplasia and goiter) were identified. The most precise bCT thresholds for the identification of MTC were ≥46 pg/ml for males (sensitivity: 93.6%, specificity: 95.0%, PPV: 97%, NPV: 90%) and ≥35 pg/ml for females (sensitivity: 87.3%, specificity: 87.5%, PPV: 98%, NPV: 50%). Using these cut-offs, only 6% of male patients were not identified of having MTC, whereas 5% were false positive (having instead C cell hyperplasia). In females, the discrepancy was higher since 13% of female MTC patients were false negative by using the cut-off of ≥35 pg/ml, and 13% had false positive results (suffering from C cell hyperplasia). Gender-specific bCT cut-offs for the identification of MTC vs. C cell hyperplasia and non-malignancy were defined, which can be used in clinical routine. In female patients, however, the accuracy is much lower compared to males.

Circulating tumor cells (CTCs) have been shown to be a valuable prognostic marker for different solid cancers. Within the present study we quantified CTCs in thyroid cancer (TC) patients. Special focus was given to disease-free PTC patients with undetectable serum thyroglobulin (Tg) levels. Altogether, 67 TC patients (33 papillary, 20 follicular, 14 medullary) were included in the study. CTC numbers, which were normalized to 3.3×10 peripheral blood mononuclear cells, were correlated with clinical outcome. TC patients had significantly higher CTC numbers compared to controls. The number of CTCs correlated to the initial tumor stage. Importantly, in comparison to controls, differentiated TC patients with serum Tg levels<0.3 ng/ml (no evidence of tumor recurrence) revealed a significantly higher amount of CTCs, also associated to their former tumor stage. Regarding the tumor-free papillary TC (PTC) patients the number of CTCs additionally correlated to the time point of radioiodine (RI) therapy: PTC patients with RI therapies>8 years before CTC measurement had significantly higher CTC numbers compared to those with RI therapy<8 years ago. We found a clear correlation between the number of CTCs and the tumor stage. Importantly, PTC patients who are in remission may still have increased numbers of CTCs. Follow-up analyses in these patients will reveal whether these data will have a clinical impact.