Parathyroid carcinoma (PC) is an ultra‐rare malignancy with a high risk of recurrence after surgery. Tumour‐directed systemic treatments for PC are not established. We used whole‐genome and RNA sequencing in four patients with advanced PC to identify molecular alterations that could guide clinical management. In two cases, the genomic and transcriptomic profiles provided targets for experimental therapies that resulted in biochemical response and prolonged disease stabilization: (a) immune checkpoint inhibition with pembrolizumab based on high tumour mutational burden and a single‐base substitution signature associated with APOBEC (apolipoprotein B mRNA editing enzyme, catalytic polypeptide‐like) overactivation; (b) multi‐receptor tyrosine kinase inhibition with lenvatinib due to overexpression of FGFR1 (Fibroblast Growth Factor Receptor 1) and RET (Ret Proto‐Oncogene) and, (c) later in the course of the disease, PARP (Poly(ADP‐Ribose) Polymerase) inhibition with olaparib prompted by signs of defective homologous recombination DNA repair. In addition, our data provided new insights into the molecular landscape of PC with respect to the genome‐wide footprints of specific mutational processes and pathogenic germline alterations. These data underscore the potential of comprehensive molecular analyses to improve care for patients with ultra‐rare cancers based on insight into disease biology.

Objective: Ectopic Cushing′s syndrome (ECS) induced by medullary thyroid cancer (MTC) is rare, and data on clinical characteristics, treatment and outcome are limited.Design: Retrospective cohort study in three German and one Swiss referral centres.Patients: Eleven patients with MTC and occurrence of ECS and 22 matched MTC patients without ECS were included.Measurements: The primary endpoint of this study was the overall survival (OS) in MTC patients with ECS versus 1:2 matched MTC patients without ECS.Results: The median age at diagnosis of ECS was 59 years (range: 35–81) and the median time between initial diagnosis of MTC and diagnosis of ECS was 29 months (range: 0–193). Median serum morning cortisol was 49 µg/dl (range: 17–141, normal range: 6.2–18). Eight (73%) patients received treatment for ECS. Treatment of ECS consisted of bilateral adrenalectomy (BADX) in four (36%) patients and adrenostatic treatment in eight (73%) patients. One patient received treatment with multityrosine kinase inhibitor (MKI) to control hypercortisolism. All patients experienced complete resolution of symptoms of Cushing's syndrome and biochemical control of hypercortisolism. Patients with ECS showed a shorter median OS of 87 months (95% confidence interval [95% CI]: 64–111) than matched controls (190 months, 95% CI: 95–285). Of the nine deaths, four were related to progressive disease (PD). Four patients showed PD as well as complications and comorbidities of hypercortisolism before death.Conclusion: This study shows that ECS occurs in advanced stage MTC and is associated with a poor prognosis. Adrenostatic treatment and BADX were effective systemic treatment options in patients with MTC and ECS to control their hypercortisolism. MKI treatment achieved complete remission of hypercortisolism and sustained tumour control in one treated case.

Background: Moderately elevated plasma normetanephrine (NMN) levels are frequent among patients with suspected pheochromocytoma and paraganglioma (PPGL). Clonidine suppression testing (CST) is recommended to distinguish patients with from those without PPGL. We aimed at evaluating the diagnostic outcome of CST in patients with moderate NMN elevations. Methods: Data from patients participating in the PMT study (Prospective Monoamine-Producing Tumor) and the ENSAT (European Network for the Study of Adrenal Tumours) registry in 6 European reference centers were analyzed retrospectively. Eighty-nine patients with suspected PPGL and moderate NMN elevations upon screening were included. During follow-up, PPGL was confirmed in 16 and excluded in 73 cases. Plasma NMN was measured by liquid chromatography tandem mass spectrometry before and 180 minutes after oral clonidine. Receiver operating characteristic analysis was performed to identify optimal cutoffs. Results: If published diagnostic criteria for CST (ie, NMN ≥112 ng/L and NMN suppression <40%) were applied, a sensitivity of 88% (CI, 61%–98%) and a specificity of 97% (CI, 90%–100%) were observed. An improved cutoff for plasma NMN 180 minutes after clonidine was established at 80% of the age-related upper limit of normal, resulting in a sensitivity of 94% and a specificity of 97%. False-negative CST results occurred in 2 patients with small PPGL. Conclusions: This study, involving one of the largest cohorts of patients with suspected PPGL and moderately elevated NMN, confirmed the diagnostic accuracy of CST. The application of an adapted cutoff further improved sensitivity.

Context Adrenal vein sampling (AVS) represents the current diagnostic gold standard for differentiation between unilateral and bilateral primary aldosteronism (PA). Postural stimulation testing (PST) has been used to provide additional diagnostic information. Objective This work aimed to evaluate the diagnostic utility of PST in the differential diagnosis of PA. Methods This cohort study was conducted at a single tertiary reference center. We analyzed 106 PST performed between 2008 and 2020. Diagnosis of PA and cause of PA were determined according to the Endocrine Society Clinical Practice Guideline, taking into account results of saline infusion testing, AVS, preoperative imaging, and outcome after medical or surgical treatment. The suggested cutoffs for the diagnosis of unilateral PA were revisited and optimized for high specificity using receiver operating characteristics (ROC) analysis. Results A total of 106 patients had confirmed PA (unilateral PA: n = 55, bilateral PA: n = 29, AVS unsuccessful/declined by patients: n = 22). Based on decreased aldosterone plasma concentration of 28% or more after 4 hours in the upright position, the PST showed a sensitivity of 36.4% at a specificity of 100% to identify unilateral disease (area under the curve [AUC] = 0.72; 95% CI, 0.62-0.83; P = .001). In patients with valid testing (drop of cortisol of 10% or more after 4 hours, n = 53) the sensitivity of PST rose to 51.4% at a specificity of 100% (AUC = 0.77; 95% CI, 0.65-0.90; P = .001). Conclusion The high specificity of 100% for the detection of unilateral PA in patients with decreased aldosterone by at least 28% after 4 hours makes PST a simple, noninvasive contribution to subtype differentiation in PA.

Serum liquid chromatography–tandem mass spectrometry (LC–MS/MS) steroid profiling is used for the diagnosis of adrenocortical carcinoma (ACC). Guidelines recommend endocrine work-up in addition to radiological imaging for follow-up in ACC, but data on this topic are scarce. Patients were included in this retrospective study if pre-therapeutic hormone values, regular tumour evaluation by imaging, steroid measurements by LC–MS/MS, and details on therapies were available. The utility of steroid profiles in detecting recurrence or disease progression was assessed, whereby “endocrine progress” was defined by an elevation of at least 3 of 13 analysed hormones. Cohort A included 47 patients after R0 resection, of whom 15 experienced recurrence and 32 did not. In cohort B, 52 patients with advanced disease (including 7 patients of cohort A with recurrence) could be evaluated on 74 visits when progressive disease was documented. In 20 of 89 cases with documented disease progression, “endocrine progress” was detectable prior to radiological progress. In these cases, recurrence/progression was detected at a median of 32 days earlier by steroid measurement than by imaging, with 11-deoxycortisol and testosterone being the most sensitive markers. Notably, these patients had significantly larger tumour burden. In conclusion, steroid profiling by LC–MS/MS is of value in detecting recurrent/progressive disease in ACC.

Background: RET (rearranged during transfection) variants are the most prevalent oncogenic events in medullary thyroid cancer (MTC). In advanced disease, multi-tyrosine kinase inhibitors (MKIs) cabozantinib and vandetanib are the approved standard treatment irrespective of RET status. The actual outcome of patients with RET-positive MTC treated with MKIs is ill described. Methods: We here retrospectively determined the RET oncogene variant status with a targeted DNA Custom Panel in a prospectively collected cohort of 48 patients with advanced MTC treated with vandetanib and/or cabozantinib at four German referral centers. Progression-free survival (PFS) and overall survival (OS) probabilities were estimated using the Kaplan-Meier method. Results: In total, 44/48 (92%) patients had germline or somatic RET variants. The M918T variant was found in 29/44 (66%) cases. In total, 2/32 (6%) patients with a somatic RET variant had further somatic variants, while in 1/32 (3%) patient with a germline RET variant, additional variants were found. Only 1/48 (2%) patient had a pathogenic HRAS variant, and no variants were found in 3 cases. In first-line treatment, the median OS was 53 (95% CI (95% confidence interval), 32–NR (not reached); n = 36), and the median PFS was 21 months (12–39; n = 33) in RET-positive MTC patients. In second-line treatment, the median OS was 18 (13–79; n = 22), and the median PFS was 3.5 months (2–14; n = 22) in RET-positive cases. Conclusions: RET variants were highly prevalent in patients with advanced MTC. The treatment results in RET-positive cases were similar to those reported in unselected cohorts.