Pediatric Medullary Thyroid Carcinoma: Clinical Presentations and Long-term Outcomes in 144 Patients Over Six Decades.

CONTEXT: Sporadic medullary thyroid carcinoma (sMTC) rarely occurs in childhood and no studies have specifically focused on this entity. OBJECTIVE: To describe the clinical presentations and long-term outcomes of a large cohort of children and young adults with sMTC compared with hereditary MTC (hMTC). METHODS: Retrospective study of 144 patients diagnosed with MTC between 1961-2019 at an age ≤21 years and evaluated at a tertiary referral center. RESULTS: In contrast to hMTC (n=124/144, 86%), patients with sMTC (n=20/144, 14%) are older (p<0.0001), have larger tumors (p<0.0001), a higher initial stage grouping (p=0.001) and have more structural disease (p=0.0045) and distant metastases (DM) (p=0.00084) at last follow up, but are not more likely to die from MTC (p=0.42). Among 77 patients diagnosed clinically, not by family history (20/20 sMTC and 57/124 hMTC), there was no difference in the initial stage (p=0.27), presence of DM at diagnosis (p=1.0), disease status at last follow-up (p=0.13), overall survival (p=0.57), or disease specific survival (p=0.87). Of the twelve sMTC tumors that underwent somatic testing, eleven (91%) had an identifiable alteration: ten RET gene alterations and one ALK fusion. CONCLUSIONS: sMTC is primarily a RET-driven disease that represents 14% of childhood-onset MTC in this cohort. Pediatric sMTC patients are older, present with clinical disease at a more advanced TNM classification, and have more persistent disease at last follow up compared with hMTC, but these differences disappear when comparing those presenting clinically. Somatic molecular testing should be considered in sMTC patients who would benefit from systemic therapy.

Assessing patient attitudes toward genetic testing for hereditary hematologic malignancy.

Since 2003, more than 15 genes have been identified to predispose to hereditary hematologic malignancy (HHM). Although the yield of germline analysis for leukemia appears like that of solid tumors, genetic referrals in adults with leukemia remain underperformed. We assessed leukemia patients' attitudes toward genetic testing and leukemia-related distress through a survey of 1093 patients diagnosed with acute or chronic leukemia, myelodysplastic syndrome, or aplastic anemia. Principal component analysis (PCA) was used to analyze patient attitudes. Distress was measured through the Impact of Event Scale-Revised (IES-R). Exactly 19.8% of eligible respondents completed the survey. The majority reported interest in (77%) or choosing to have (78%) genetic testing for HHM. Slightly over half identified worry about cost of genetic testing (58%) or health insurance coverage (61%) as possible barriers. PCA identified relevant themes of interest in genetic testing, impact on leukemia treatment, discrimination and confidentiality, psychosocial and familial impacts, and cost of testing. The majority reported low distress. Leukemia patients report high interest in genetic testing, few barriers, and relatively low distress.

Understanding the clinical course of genotype-negative MEN1 patients can inform management strategies.

BACKGROUND: It is unclear whether genotype-negative clinical multiple endocrine neoplasia type 1 patients derive equal benefit from prospective surveillance as genotype-positive patients. METHODS: In this retrospective cohort study, we compared genotype-negative patients with clinical multiple endocrine neoplasia type 1 with genotype-positive index cases. Primary outcome was age-related penetrance of manifestations; secondary outcomes were disease-specific survival and clinical course of endocrine tumors. RESULTS: We included 39 genotype-negative patients with clinical multiple endocrine neoplasia type 1 (Male: 33%) and 63 genotype-positive multiple endocrine neoplasia type 1 index cases (Male: 59%). Genotype-negative patients with clinical multiple endocrine neoplasia type 1 were 65 years old at last follow-up; genotype-positive multiple endocrine neoplasia type 1 index cases were 50 (P < .001). Genotype-negative patients with clinical multiple endocrine neoplasia type 1 were significantly older at their first and second primary manifestation. Only 1 developed a third primary manifestation. No genotype-negative patients with clinical multiple endocrine neoplasia type 1 with primary hyperparathyroidism and a pituitary adenoma developed a duodenopancreatic neuroendocrine tumor. Disease-specific survival was significantly better in genotype-negative patients with clinical multiple endocrine neoplasia type 1. In genotype-negative patients with clinical multiple endocrine neoplasia type 1, primary hyperparathyroidism was single-gland disease in 47% of parathyroidectomies versus 0% in genotype-positive multiple endocrine neoplasia type 1 index cases. In genotype-negative patients with clinical multiple endocrine neoplasia type 1, 17% of duodenopancreatic neuroendocrine tumors were multifocal versus 68% in genotype-positive multiple endocrine neoplasia type 1 index cases. Genotype-negative patients with clinical multiple endocrine neoplasia type 1 had more pituitary macroadenomas, fewer prolactinomas, and more somatotroph adenomas. CONCLUSION: Genotype-negative patients with clinical multiple endocrine neoplasia type 1 have a different clinical course than genotype-positive multiple endocrine neoplasia type 1 index cases. This may support a separate classification and a tailored surveillance regimen. Of the genotype-negative patients with clinical multiple endocrine neoplasia type 1 who had parathyroidectomy, almost half had no evidence of multigland disease and may be potential candidates for a more targeted single-gland approach.

Recontacting Patients with Updated Genetic Testing Recommendations for Medullary Thyroid Carcinoma and Pheochromocytoma or Paraganglioma.

BACKGROUND: No guidelines exist regarding physicians' duty to inform former patients about novel genetic tests that may be medically beneficial. Research on the feasibility and efficacy of disseminating information and patient opinions on this topic is limited. METHODS: Adult patients treated at our institution from 1950 to 2010 for medullary thyroid cancer, pheochromocytoma, or paraganglioma were included if their history suggested being at-risk for a hereditary syndrome but genetic risk assessment would be incomplete by current standards. A questionnaire assessing behaviors and attitudes was mailed 6 weeks after an information letter describing new genetic tests, benefits, and risks was mailed. RESULTS: Ninety-seven of 312 (31.1%) eligible patients with an identified mailing address returned the questionnaire. After receiving the letter, 29.2% patients discussed genetic testing with their doctor, 39.3% considered pursuing genetic testing, and 8.5% underwent testing. Nearly all respondents (97%) indicated that physicians should inform patients about new developments that may improve their or their family's health, and 71% thought patients shared this responsibility. Most patients understood the letter (84%) and were pleased it was sent (84%), although 11% found it upsetting. CONCLUSIONS: Patients believe it is important for physicians to inform them of potentially beneficial developments in genetic testing. However, physician-initiated letters to introduce new information appear inadequate alone in motivating patients to seek additional genetic counseling and testing. Further research is needed regarding optimal methods to notify former patients about new genetic tests and corresponding clinical and ethical implications.

A Homozygous RET K666N Genotype With an MEN2A Phenotype.

Context: Germline RET K666N mutation has been described as a pathogenic mutation with low disease penetrance for medullary thyroid cancer (MTC) without other features of multiple endocrine neoplasia type 2A. We describe a patient with homozygous RET K666N mutation with MTC and bilateral pheochromocytoma (PHEO). Case Description: A 59-year-old woman received a diagnosis of MTC after biopsy of two thyroid nodules. Coincident biochemical and radiologic testing was suspicious for bilateral PHEO, confirmed after bilateral adrenalectomy. There was no evidence of primary hyperparathyroidism (PHPT). She had a total thyroidectomy with neck dissection revealing bilateral MTC with lymph node metastases. Germline RET testing identified homozygous K666N mutations. Genetic testing of family members showed that both adult children harbor a heterozygous K666N mutation. Her 32-year-old son had an elevated calcitonin level and underwent thyroidectomy, which identified MTC. Her 30-year-old daughter had a normal calcitonin level. Prophylactic thyroidectomy showed C-cell hyperplasia only. Three of seven other family members were tested and found to carry the mutation. All had normal calcitonin levels, and none had biochemical evidence of PHEO or PHPT. Given the absence of PHEO in reported RET K666N families, our proband underwent genetic testing for causes of hereditary paragangliomas or PHEO. No additional mutations were identified. Conclusions: Here we report a case of a homozygous RET K666N mutation leading to coincident MTC and PHEO. Heterozygous presentations of RET K666N mutations have low penetrance for isolated MTC. We believe that the gene dosage associated with the homozygosity of this variant contributed to the occurrence of bilateral PHEO.

Genotype-phenotype pancreatic neuroendocrine tumor relationship in multiple endocrine neoplasia type 1 patients: A 23-year experience at a single institution.

BACKGROUND: The aim of this study was to investigate the genotype-phenotype relationship of pancreatic neuroendocrine tumors in patients with multiple endocrine neoplasia type 1 treated at our institution. METHODS: We conducted a retrospective chart review of all patients with multiple endocrine neoplasia type 1 treated at our center from January 1993 to December 2015. Presence of a pancreatic neuroendocrine tumor was determined based on imaging performed at any time from presentation to conclusion of follow-up. RESULTS: We reviewed 188 patients. The most common site of multiple endocrine neoplasia type 1 mutation was in exon 2 (34/188; 18%). Of 188 patients, 125 had a pancreatic neuroendocrine tumor (61%). Among all patients, 30 of 34 (88%) with an exon 2 mutation had a pancreatic neuroendocrine tumor compared with 95 of 154 (62%) with a mutation in exons 3-10 (P = .002). In the age group of 20 to 40 years, 8 of 9 patients with an exon 2 mutation had a pancreatic neuroendocrine tumor, compared with 24 of 52 patients (46%) with a mutation in exons 3-10 (P = .028). Patients with an exon 2 mutation had a greater frequency of pancreatic neuroendocrine tumor distant metastasis (53% vs 23%, P = .049). CONCLUSION: Young patients with multiple endocrine neoplasia type 1 and an exon 2 mutation appear to have a 2-fold greater risk for developing a pancreatic neuroendocrine tumor, and patients with an exon 2 mutation may be at greater risk for developing distant metastasis. Consideration should be given to more intensive screening and more liberal application of primary operative intervention in this potentially high-risk group.

Medullary Thyroid Carcinoma in MEN2A: ATA Moderate- or High-Risk RET Mutations Do Not Predict Disease Aggressiveness.

Context: High-risk RET mutations (codon 634) are associated with earlier development of medullary thyroid carcinoma (MTC) and presumed increased aggressiveness compared with moderate-risk RET mutations. Objective: To determine whether high-risk RET mutations are more aggressive. Design: Retrospective cohort study using institutional multiple endocrine neoplasia type 2 registry. Setting: Tertiary cancer care center. Patients: Patients with MTC and moderate- or high-risk germline RET mutation. Intervention: None (observational study). Main Outcome Measures: Proxies for aggressiveness were overall survival (OS) and time to distant metastatic disease (DMD). Results: A total of 127 moderate-risk and 135 high-risk patients were included (n = 262). Median age at diagnosis was 42.3 years (range, 6.4 to 86.4 years; mean, 41.6 years) for moderate-risk mutations and 23.0 years (range, 3.7 to 66.8 years; mean, 25.6 years) for high-risk mutations (P < 0.0001). Moderate-risk patients had more T3/T4 tumors at diagnosis (P = 0.03), but there was no significant difference for N or M stage and no significant difference in OS (P = 0.40). From multivariable analysis for OS, increasing age [hazard ratio (HR), 1.05/y; 95% confidence interval (CI), 1.03 to 1.08], T3/T4 tumor (HR, 2.73; 95% CI, 1.22 to 6.11), and M1 status at diagnosis (HR, 3.93; 95% CI, 1.61 to 9.59) were significantly associated with worse OS but high-risk mutation was not (P = 0.40). No significant difference was observed for development of DMD (P = 0.33). From multivariable analysis for DMD, only N1 status at diagnosis was significant (HR, 2.10; 95% CI, 1.03 to 4.27). Conclusions: Patients with high- and moderate-risk RET mutations had similar OS and development of DMD after MTC diagnosis and therefore similarly aggressive clinical courses. High-risk connotes increased disease aggressiveness; thus, future guidelines should consider RET mutation classification by disease onset (early vs late) rather than by risk (high vs moderate).

Genetics of Multiple Endocrine Neoplasia Type 1/Multiple Endocrine Neoplasia Type 2 Syndromes.

Multiple endocrine neoplasia syndromes types 1 and 2 represent well-characterized yet clinically heterogeneous hereditary conditions for which diagnostic and management recommendations exist; genetic testing for these inherited endocrinopathies is included in these guidelines and is an important part of identifying affected patients and their family members. Understanding of these mature syndromes is challenged as more individuals undergo genetic testing and genetic data are amassed, with the potential to create clinical conundrums that may have an impact on individualized approaches to management and counseling. Clinicians who diagnose and treat patients with MEN syndromes should be aware of these possibilities.

Medullary Thyroid Carcinoma Associated with Germline RETK666N Mutation.

BACKGROUND: Multiple endocrine neoplasia type 2 is an autosomal dominant inherited syndrome caused by activating mutations in the RET proto-oncogene. The RETK666N DNA variant was previously reported in two isolated medullary thyroid carcinoma (MTC) cases, but no family studies are available, and its oncogenic significance remains unknown. METHODS: The clinical features, genetic data, and family information of eight index MTC patients with a germline RETK666N variant were assessed. RESULTS: Four probands presented with MTC and extensive nodal metastasis, one with biopsy-confirmed distant metastasis. Two additional probands presented with localized disease. However, nodal status was not available. Of the final two probands, one had an incidental 1.5 mm MTC and C-cell hyperplasia uncovered after surgery for papillary thyroid carcinoma, and one had two foci of MTC (largest dimension 2.3 cm) detected after surgery for dysphagia. Genetic screening identified 16 additional family members carrying the K666N variant (aged 5-90 years), 11 of whom have documented evaluation for MTC. Of these, only two were found to have elevated basal serum calcitonin upon screening, and the remaining patients had calcitonin levels within the reference range. One patient who elected to have a thyroidectomy at 70 years of age was confirmed to have MTC. The other subject, 57 years old, elected surveillance. Four prophylactic thyroidectomies were performed, with one case of C-cell hyperplasia at 20 years and three cases that revealed normal pathology at ages 21, 30, and 30 years. None of the K666N DNA variant carriers had evidence of primary hyperparathyroidism or pheochromocytoma. CONCLUSIONS: From this case series, the largest such experience to date, it is concluded that the RETK666N variant is likely pathogenic and associated with low penetrance of MTC. However, the findings are insufficient to define its pathogenicity clearly and make firm recommendations for screening and treatment. Given the potential benefit associated with early detection of aberrant C-cell growth, and the noninvasive nature of genetic testing, "at risk" individuals should be screened, and if the K666N variant is identified, they should be managed using a personalized screening approach for detection of MTC.

Parathyroid carcinoma and atypical parathyroid neoplasms in MEN1 patients; A clinico-pathologic challenge. The MD Anderson case series and review of the literature.

BACKGROUND: Multiple endocrine neoplasia type 1 (MEN1) is a genetic disorder characterized by usually benign tumors of the parathyroid glands, pancreatic islet cells, and anterior pituitary. Hyperparathyroidism (HPT) occurs in 90% of MEN1 patients. In rare cases, it is associated with parathyroid carcinoma (PC) or atypical parathyroid neoplasm (APN). We present a cohort of 3 such patients. METHODS: We performed a retrospective review of our institution's MEN1 database to identify patients who underwent operations for HPT and had a histopathologic diagnosis of PC or APN. Clinical features, genetics, and outcomes were summarized. RESULTS: Of 291 MEN1 patients, 242 had HPT (83.2%). Two of the 242 patients (0.8%) had a histopathologic diagnosis of PC, and 1 (0.4%) had a diagnosis of APN. The patients with PC were male, ages 62 and 56 years at the time of surgery; the patient with APN was female, age 32 years. All patients also had a pancreatic endocrine tumor. The observed genetic mutations in the PC patients were c.703G > A (p.E235K) in exon 4 and c.1378C > T (p.R460X) in exon 10. All 3 patients had recurrence of hypercalcemia, and 2 patients underwent reoperation; pathologic analysis revealed the presence of a hyperplastic gland, not tumor recurrence. No cases had distant metastasis. CONCLUSIONS: This is the first report of APN in an MEN1 patient. Although rare, the presence of PC or APN in MEN1 is noteworthy because it affects the management if hypercalcemia recurs, possibly requiring an open approach rather than the minimally invasive techniques used in the reoperative setting for benign disease.