Cristina Romei

BRAF(V600E) mutation and outcome of patients with papillary thyroid carcinoma: a 15-year median follow-up study.

BACKGROUND The BRAF(V600E) mutation is the most frequent genetic alteration in papillary thyroid carcinoma (PTC). The role of BRAF(V600E) mutation as a poor prognostic factor has been controversially reported in series with short-term follow-ups. In this study we verified the prognostic value of the BRAF(V600E) mutation in PTC patients with a long-term follow-up. METHODS We studied 102 PTC patients with a median follow-up of 15 yr. The BRAF(V600E) mutation was analyzed by PCR-single-strand conformational polymorphism and sequencing. The correlation between the presence/absence of the BRAF(V600E) mutation, clinicopathological features, and outcome of PTC patients were evaluated. RESULTS The BRAF(V600E) mutation was found in 38 of 102 (37.3%) PTC patients, and was significantly more frequent in patients older than 60 yr (P = 0.02), in advanced stages (P = 0.03), and in cases with vascular invasion (P = 0.02). At univariate analysis the worst outcome for PTC patients was significantly correlated with clinicopathological features (i.e. age, tumor size, extrathyroid extension, lymph node and distant metastases, advanced stage, vascular endothelial growth factor expression, and vascular invasion) and the BRAF(V600E) mutation (P < 0.002). However, at multivariate analysis only the BRAF(V600E) mutation showed an independent correlation with the worst outcome (P = 0.03). Moreover, the survival curves of PTC patients showed a lower percentage of survivors in the BRAF(V600E)-mutated group (P = 0.015). CONCLUSIONS In this study the BRAF(V600E) mutation correlated with the worst outcome for PTC patients, who were not only at a higher risk not to be cured but also for death. In particular, the BRAF(V600E) mutation was demonstrated to be a poor prognostic factor independent from other clinicopathological features.

The BRAF(V600E) mutation is an independent, poor prognostic factor for the outcome of patients with low-risk intrathyroid papillary thyroid carcinoma: single-institution results from a large cohort study

BACKGROUND The BRAF(V600E) mutation, the most frequent genetic alteration in papillary thyroid carcinoma (PTC), was demonstrated to be a poor prognostic factor. The aim of this study was to evaluate its prognostic significance in a large cohort of low-risk intrathyroid PTC. METHODS Among the 431 consecutive PTC patients, we selected 319 patients with an intrathyroid tumor and no metastases (T1-T2, N0, M0). The BRAF(V600E) mutation was analyzed by PCR-single-strand conformation polymorphism analysis and direct genomic sequencing. The correlation between the presence/absence of the mutation, the clinical-pathological features, and the outcome of the PTC patients was investigated. RESULTS The BRAF(V600E) mutation was present in 106 of 319 PTC patients (33.2%). Its prevalence was also the same in subgroups identified according to the level of risk. The BRAF(V600E) mutation correlated with multifocality, aggressive variant, absence, or infiltration of the tumoral capsule. BRAF(V600E)-mutated PTC also required a higher number of radioiodine courses to obtain disease-free status. The BRAF(V600E) mutation was the only prognostic factor predicting the persistence of the disease in these patients after 5 yr of follow-up. CONCLUSIONS The BRAF(V600E) mutation was demonstrated to be a poor prognostic factor for the persistence of the disease independent from other clinical-pathological features in low-risk intrathyroid PTC patients. It could be useful to search for the BRAF(V600E) mutation in the workup of low-risk PTC patients to distinguish those who require less or more aggressive treatments. In particular, the high negative predictive value of the BRAF(V600E) mutation could be useful to identify, among low-risk PTC patients, those who could avoid 131-I treatment.

Evidence of a Low Prevalence of RAS Mutations in a Large Medullary Thyroid Cancer Series

BACKGROUND Approximately 60% of sporadic medullary thyroid carcinomas (sMTC) remain orphan of a recognized genetic cause. Recently, a high percentage of RAS point mutations have been described in RET-negative sMTC. The aim of this study was to assess the prevalence of RAS point mutations in a large series of MTC collected in four Italian centers. METHODS For this purpose, we studied codons 12, 13, and 61 of H-, K-, and N-RAS genes in 188 MTC samples, either hereditary or sporadic, by direct sequencing. Correlations between the RAS mutational status and the clinical-pathological features of MTC patients as well as a meta-analysis of all published data were performed. RESULTS The prevalence of RAS mutations in the present series of MTC was 10.1%, and 17.6% when considering only RET-negative cases. RAS mutations were found in MTC tumoral tissue, but not in peripheral blood indicating their somatic origin. A novel mutation in codon 72 (M72I) was found, but with a low or null transforming potential. No association was found between the presence of RAS mutations and the clinical-pathological features of the patients. Although not statistically significant, a positive association between the presence of RAS mutations and a better outcome was observed. The meta-analysis of all published studies confirmed a prevalence of 8.8% for RAS mutations in MTC. CONCLUSIONS The prevalence of RAS mutations in our MTC series was relatively low and consistent with the meta-analysis data. Only somatic RAS mutations were found and only in RET-negative sMTC. Likewise, MTCs that harbor a RAS mutation identify a subgroup of tumors with less aggressive behavior. To our knowledge, this is the largest series of MTCs studied for the presence of mutations in RAS genes and the first meta-analysis on this specific topic.

Prophylactic Central Compartment Lymph Node Dissection in Papillary Thyroid Carcinoma: Clinical Implications Derived From the First Prospective Randomized Controlled Single Institution Study

BACKGROUND The benefits of prophylactic central compartment lymph node dissection (pCCND) in papillary thyroid cancer (PTC) are still under investigation. This treatment seems to reduce PTC recurrence/mortality rates but has a higher risk of surgical complications. The lack of prospective randomized trials does not allow definitive recommendations. The aim of this prospective randomized controlled study was to evaluate the clinical advantages and disadvantages of pCCND. PATIENTS A total of 181 patients with PTC without evidence of preoperative/intraoperative lymph node metastases (cN0) were randomly assigned to either Group A (n = 88) and treated with total thyroidectomy (TTx) or Group B (n = 93) and treated with TTx + pCCND. RESULTS After 5 years of followup, no difference was observed in the outcome of the two groups. However, a higher percentage of Group A were treated with a higher number of (131)I courses (P = .002), whereas a higher prevalence of permanent hypoparathyroidism was observed in Group B (P = .02). No preoperative predictors of central compartment lymph node metastases (N1a) were identified. Only three patients were upstaged, and the therapeutic strategy changed in only one case. CONCLUSIONS cN0 patients with PTC treated either with TTx or TTx + pCCND showed a similar outcome. One advantage of TTx + pCCND was a reduced necessity to repeat (131)I treatments, but the disadvantage was a higher prevalence of permanent hypoparathyroidism. Almost 50% of patients with PTC had micrometastatic lymph nodes in the central compartment, but none of the presurgical features analyzed, including BRAF mutation, was able to predict their presence; moreover, to be aware of their presence does not seem to have any effect on the outcome.

Multiple endocrine neoplasia type 2 syndromes (MEN 2): results from the ItaMEN network analysis on the prevalence of different genotypes and phenotypes

OBJECTIVE Multiple endocrine neoplasia type 2 (MEN 2) is a genetic disease characterized by medullary thyroid carcinoma (MTC) associated (MEN 2A and 2B) or not familial MTC (FMTC) with other endocrine neoplasia due to germline RET gene mutations. The prevalence of these rare genetic diseases and their corresponding RET mutations are unknown due to the small size of the study population. METHODS We collected data on germline RET mutations of 250 families with hereditary MTC followed in 20 different Italian centres. RESULTS AND CONCLUSIONS The most frequent RET amino acid substitution was Val804Met (19.6%) followed by Cys634Arg (13.6%). A total of 40 different germline RET mutations were present. Six families (2.4%) were negative for germline RET mutations. The comparison of the prevalence of RET germline mutations in the present study with those published by other European studies showed a higher prevalence of Val804Met and Ser891Ala mutations and a lower prevalence of Leu790Phe and Tyr791Phe (P<0.0001). A statistically significant higher prevalence of mutations affecting non-cysteine codons was also found (P<0.0001). Furthermore, the phenotype data collection showed an unexpected higher prevalence of FMTC (57.6%) with respect to other MEN 2 syndromes (34% MEN 2A and 6.8% of MEN 2B). In conclusion, we observed a statistically significant different pattern of RET mutations in Italian MEN 2 families with respect to other European studies and a higher prevalence of FMTC phenotype. The different ethnic origins of the patients and the particular attention given to analysing apparently sporadic MTC for RET germline mutations may explain these findings.

Early treatment of hereditary medullary thyroid carcinoma after attribution of multiple endocrine neoplasia type 2 gene carrier status by screening for ret gene mutations.

BACKGROUND Germline missense point mutations of the ret proto-oncogene have been shown as causative in multiple endocrine neoplasia type 2 (MEN 2A and 2B) and in familial medullary thyroid carcinoma (FMTC). Most of the mutations are found in exon 10, 11, or 16 of the gene and are easily recognized by restriction analysis. METHODS Using restriction analysis, we screened 58 subjects from nine kindreds. RESULTS Family members (n = 16) already known to be affected with the disease carried the germline mutation. Among the 42 subjects apparently unaffected, 37 were not gene carriers and 5 were gene carriers. Basal and pentagastrin-stimulated serum calcitonin levels were normal in two patients and abnormal in three. All patients were treated with total thyroidectomy and central node dissection. In all cases multiple foci of MTC were shown at histologic examination. CONCLUSIONS Our data indicate that genetic screening of MEN2 pedigrees allows the early identification of gene carriers. Because surgery of MTC in the preclinical phase has high probability of curing these patients, we suggest genetic screening soon after birth and total thyroidectomy in gene carriers as early as possible.

RET/PTC Translocations and Clinico-Pathological Features in Human Papillary Thyroid Carcinoma

Thyroid carcinoma is the most frequent endocrine cancer accounting for 5–10% of thyroid nodules. Papillary histotype (PTC) is the most prevalent form accounting for 80% of all thyroid carcinoma. Although much is known about its epidemiology, pathogenesis, clinical, and biological behavior, the only documented risk factor for PTC is the ionizing radiation exposure. Rearrangements of the Rearranged during Transfection (RET) proto-oncogene are found in PTC and have been shown to play a pathogenic role. The first RET rearrangement, named RET/PTC, was discovered in 1987. This rearrangement constitutively activates the transcription of the RET tyrosine-kinase domain in follicular cell, thus triggering the signaling along the MAPK pathway and an uncontrolled proliferation. Up to now, 13 different types of RET/PTC rearrangements have been reported but the two most common are RET/PTC1 and RET/PTC3. Ionizing radiations are responsible for the generation of RET/PTC rearrangements, as supported by in vitro studies and by the evidence that RET/PTC, and particularly RET/PTC3, are highly prevalent in radiation induced PTC. However, many thyroid tumors without any history of radiation exposure harbor similar RET rearrangements. The overall prevalence of RET/PTC rearrangements varies from 20 to 70% of PTCs and they are more frequent in childhood than in adulthood thyroid cancer. Controversial data have been reported on the relationship between RET/PTC rearrangements and the PTC prognosis. RET/PTC3 is usually associated with a more aggressive phenotype and in particular with a greater tumor size, the solid variant, and a more advanced stage at diagnosis which are all poor prognostic factors. In contrast, RET/PTC1 rearrangement does not correlate with any clinical–pathological characteristics of PTC. Moreover, the RET protein and mRNA expression level did not show any correlation with the outcome of patients with PTC and no correlation between RET/PTC rearrangements and the expression level of the thyroid differentiation genes was observed. Recently, a diagnostic role of RET/PTC rearrangements has been proposed. It can be searched for in the mRNA extracted from cytological sample especially in case with indeterminate cytology. However, both the fact that it can be present in a not negligible percentage of benign cases and the technical challenge in extracting mRNA from cytological material makes this procedure not applicable at routine level, at least for the moment.

The Timing of Total Thyroidectomy in RET Gene Mutation Carriers Could Be Personalized and Safely Planned on the Basis of Serum Calcitonin: 18 Years Experience at One Single Center

BACKGROUND Medullary thyroid carcinoma (MTC) is a calcitonin (CT)-producing C-cell tumor. In hereditary cases, a germline RET mutation is found in 98% of families. Because MTC is cured only if intrathyroidal, prophylactic thyroidectomy is recommended in the gene carrier (GC). AIMS The aim was to determine whether thyroidectomy performed when stimulated CT becomes detectable is as safe as prophylactic thyroidectomy and to identify the serum CT cutoff able to distinguish intrathyroidal from extrathyroidal MTC. PATIENTS Eighty-four GC were prospectively enrolled; 53 of the 84 underwent total thyroidectomy, one refused surgery, and 30 with normal basal and stimulated CT were under surveillance. The follow-up ranged from 2 to 18 yr. RESULTS GC operated on for elevated stimulated CT included 27 GC with a positive peak CT at the screening and four cases who became positive after 4 yr. All of them had intrathyroidal MTC and no node metastases; all were cured after a mean follow-up of 7.5 yr. Among those operated on for detectable basal CT, intrathyroidal tumors were found when CT was below 60 pg/ml, whereas either node metastases or larger tumors were observed when CT was above 60 pg/ml. No correlation among serum CT, age, and type of RET mutation was observed. Thirty GC were still biochemically negative at the annual control. CONCLUSIONS The time of thyroidectomy in GC with negative CT could be personalized and safely planned when stimulated CT becomes positive, independent of the type of RET mutation and patients age. In this series, a basal CT below 60 pg/ml was always associated to an intrathyroidal localization of MTC.

Identification of the Cys634->Tyr mutation of the RET proto-oncogene in a pedigree with multiple endocrine neoplasia type 2A and localized cutaneous lichen amyloidosis

Following the recent identification of specific germline mutations of the RET proto-oncogene in Multiple Endocrine Neoplasia type 2A (MEN2A) patients, we looked for mutations of this gene in a pedigree showing recurrence of MEN2A and localized Cutaneous Lichen Amyloidosis (CLA). Basal calcitonin and/or pentagastrin test performed in all the 10 available members of this pedigree confirmed the clinical diagnosis and allowed the presymptomatic identification of an additional carrier. A cys634->tyr missense mutation, already reported as causative in MEN2A patients, was identified after SSCP analysis and direct sequencing of exon 11 of the RET protooncogene in one individual affected with both MEN2A and CLA, thus suggesting a common etiology for the two disorders. Taking advantage of the observation of an Rsal restriction site in the sequence surrounding the mutated codon, we could demonstrate that the same mutation is present in three other affected members, in the presymptomatic carrier and in one additional 25 years old healthy member who shows a mildly positive pentagastrin test.

RET genetic screening of sporadic medullary thyroid cancer (MTC) allows the preclinical diagnosis of unsuspected gene carriers and the identification of a relevant percentage of hidden familial MTC (FMTC)

Objective  This study was aimed to demonstrate the clinical benefits of rearranged during transfection (RET) genetic screening in patients with apparently sporadic medullary thyroid cancer (MTC) not only to identify the hereditary nature of the disease in the index case but also to discover family members harbouring the same germline mutations (i.e. gene carriers) who are unaware of their condition.