A molecular approach combined with American Thyroid Association classification better stratifies recurrence risk of classic histology papillary thyroid cancer

Comparative efficiency of differential diagnostic methods for the identification of BRAF V600E gene mutation in papillary thyroid cancer (Review)

V-Raf murine sarcoma viral oncogene homolog B1 (BRAF) encodes a serine-threonine kinase. The V600E point mutation in the BRAF gene is the most common mutation, predominantly occurring in melanoma, and colorectal, thyroid and non-small cell lung cancer. Particularly in the context of thyroid cancer research, it is routinely employed as a molecular biomarker to assist in diagnosing and predicting the prognosis of papillary thyroid cancer (PTC), and to formulate targeted therapeutic strategies. Currently, several methods are utilized in clinical settings to detect BRAF V600E mutations in patients with PTC. However, the sensitivity and specificity of various detection techniques vary significantly, resulting in diverse detection outcomes. The present review highlights the advantages and disadvantages of the methods currently employed in medical practice, with the aim of guiding clinicians and researchers in selecting the most suitable detection approach for its high sensitivity, reproducibility and potential to develop targeted therapeutic regimens for patients with BRAF gene mutation-associated PTC.

VHL tumor suppressor as a novel potential candidate biomarker in papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is the most common type of endocrine cancer, with an increasing incidence worldwide. The treatment of PTC is currently the subject of clinical controversy, making it critically important to identify molecular markers that would help improve the risk stratification of PTC patients and optimize the therapeutic approach. The VHL tumor suppressor gene has been implicated in tumorigenesis of various types of carcinoma and linked with their aggressive biological behavior. The role of VHL in the origin and development of PTC has only recently begun to be revealed. In this narrative review we attempt to summarize the existing knowledge that implicates VHL in PTC pathogenesis and to outline its potential significance as a candidate molecular biomarker for the grouping of PTC patients into high and low risk groups.

BRAF mutations in thyroid cancer

PURPOSE OF REVIEW

Activating mutations in the mitogen-activated protein kinase (MAPK) pathway play an important role in papillary (PTC) and anaplastic (ATC) thyroid cancer. The aim of this review is to discuss the impact of BRAF mutations on clinical features and treatment of patients with thyroid cancer.

RECENT FINDINGS

Despite the unfavorable course associated with PTCs harboring BRAF V600E mutation, its prognostic role remains debated. BRAF V600E-driven tumors exhibit high Extracellular signal-regulated kinase phosphorylation, leading to unregulated cell proliferation and inhibition of the required genes for radioiodine responsiveness in thyroid cancer. The mechanism associated with the variable BRAF-mutant tumor aggressiveness remains unclear and other pathways are likely to co-operate to promote cancer progression. Overexpression of the Notch signaling and loss of individual switch/ sucrose non-fermentable chromatin-remodeling complexes subunits might be involved. The combination of the BRAF inhibitor dabrafenib and the mitogen-activated protein kinase kinase inhibitor trametinib has shown remarkable results in clinical trials of patients with BRAF-mutated ATCs.

SUMMARY

The impact of BRAF mutations on the clinical outcomes of PTC remains debatable. In ATCs, in turn, BRAF mutations identify patients eligible for targeted therapy, which is now considered in two settings: as neoadjuvant for unresectable tumors and as a treatment for metastatic or unresectable disease.

BRAFV600E Mutation is Associated with an Increased Risk of Papillary Thyroid Cancer Recurrence

BACKGROUND

Papillary thyroid carcinoma is the most common endocrine malignancy and one of the most common cancers worldwide. However, the optimal timing and frequency of surveillance to assess for recurrence remain undetermined. As the incidence of thyroid cancer continues to rise worldwide, identifying risk factors for recurrence and investigating intervals and durations of surveillance are paramount to adapt treatment and follow-up plans to high-risk individuals and to reduce interventions for low-risk patients.

METHODS

Our dataset included an unselected cohort of papillary thyroid carcinoma (PTC) patients who underwent a total thyroidectomy (or unilateral then completion thyroidectomy) at a single institution from 2000 to 2007. BRAF genotyping was performed on available specimens by a validated PCR-based assay. Pathologic structural recurrence was the primary outcome. We performed univariate and multivariable analyses to identify predictors of cancer recurrence.

RESULTS

In total, 599 patients underwent complete resection of the thyroid gland for PTC. The cohort was young (mean age 45.0 years), predominately female (n = 462, 76.9%), and median follow-up was 10.3 years (IQR 5.4-12.2). Recurrence occurred more commonly in the BRAF^V600E group (18.6 vs. 9.9%, p = 0.02). BRAF independently predicted PTC recurrence (HR 2.81, p = 0.006).

CONCLUSIONS

BRAF mutation is an independent predictor of papillary thyroid carcinoma long-term recurrence. Understanding molecular characteristics of individual thyroid cancers may help risk-stratify patients and direct them toward more appropriate initial care and long-term surveillance strategies.

The Impact of BRAF Mutation on the Recurrence of Papillary Thyroid Carcinoma: A Meta-Analysis

Previous meta-analyses indicated that the BRAF V600E mutation was associated with an increased recurrence rate of papillary thyroid carcinoma (PTC). However, with recent publications of large cohort studies, the need for an updated meta-analysis increases. Therefore, we conducted a comprehensive meta-analysis to assess the impact of the BRAF V600E mutation on PTC recurrences. We performed a literature search using PubMed, SCOPUS, the Cochrane Database of Systematic Reviews, and the Web of Science Core Collection, from their inception to May 31, 2020. The relevant studies compared recurrence rates using the hazard ratio (HR) of BRAF mutations; 11 studies comprising 4674 patients were identified and included. Recurrence rates in patients with the BRAF V600E mutation were comparable with BRAF wild-type patients (HR 1.16, 95% CI 0.78–1.71), after adjustment for possible confounders. In subgroup analysis, both geographical region (HRs for America, Asia, and Europe were 2.16, 1.31 and 0.66, respectively) and tumor stage (HRs for stage I and II were 1.51 and 4.45, respectively) can affect the HRs of the BRAF mutation for recurrence. In conclusion, the BRAF mutation does not increase the risk of recurrences in patients with PTC. Differences in the geographical region or tumor stage should be considered when interpreting the impact of a BRAF mutation on recurrence.

Peptide Profile Differences of Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features, Encapsulated Follicular Variant, and Classical Papillary Thyroid Carcinoma: An Application of Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging

Introduction: The lack of papillary structures and faint and/or unclear core features of follicular variant of papillary thyroid carcinoma (FV-PTC) may hamper the definitive fine needle aspiration biopsy -based diagnosis. Recently, the nomenclature of noninvasive encapsulated FV-PTC was revised to "noninvasive follicular thyroid neoplasms with papillary-like nuclear features" (NIFTP). However, it remains inconclusive whether or not the peptide patterns differ between NIFTP and encapsulated FV-PTC. The main objectives of this study were to investigate the viability of matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) in the pathological assessment of NIFTP and to evaluate the discriminatory power of MALDI MSI for the classification of classical variant of PTC (CV-PTC), NIFTP, and encapsulated FV-PTC. Methods: MALDI MSI was employed to investigate the changes in peptide profiles from 21 formalin-fixed paraffin-embedded (FFPE) tissue samples (n = 7 from each group of CV-PTC, NIFTP, and FV-PTC). Six out of seven FV-PTC FFPE tissue samples were encapsulated FV-PTC; only one was infiltrative FV-PTC. Liquid chromatography-tandem mass spectrometry was used for the identification of the peptide signals detected in MALDI MSI. Results: Using receiver operating characteristics analysis, 10 peptide signals distinguished NIFTP from normal thyroid parenchyma (area under the curve [AUC] >0.80). To evaluate the discriminatory power of MALDI MSI, statistically significant peptide signals (n = 88) within three groups were used for hierarchical clustering. The method had high discriminatory power for distinguishing CV-PTC from NIFTP and FV-PTC (encapsulated and infiltrative). The majority of the NIFTP and encapsulated FV-PTC were clustered together, indicating that NIFTP could not be distinguished from encapsulated FV-PTC. However, infiltrative FV-PTC FFPE tissue samples had the furthest distance from all the NIFTP cases. High signal intensities of S100-A6, vimentin, and cytoplasmic actin 1 were detected in FV-PTC, prelamin A/C in CV-PTC, and 60S ribosomal protein L6 and L8 in NIFTP tissues. Conclusions: MALDI MSI, a powerful tool combining histological and mass spectrometric data, enabled the differentiation of NIFTP from normal thyroid parenchyma. Although NIFTP is a recent definition that replaces noninvasive encapsulated FV-PTC, the peptide profiles of NIFTP and encapsulated FV-PTC were found to be similar.

A molecular approach combined with American Thyroid Association classification better stratifies recurrence risk of classic histology papillary thyroid cancer

BACKGROUND

Prognosis among patients with differentiated thyroid cancer is widely variable. Better understanding of biologic subtypes is necessary to stratify patients and improve outcomes.

METHODS

In patients diagnosed with classic histology papillary thyroid cancer treated from 1973 to 2009, BRAF V600E mutation status was determined on surgical tumor specimens by restriction fragment length polymorphism analysis. A tissue microarray (TMA) was constructed from tumor specimens in triplicate and stained by immunohistochemistry for RET, phospho-MEK, MAPK(dpERK), PPARγ, and phospho-AKT(pAKT). Stained slides were scored independently and blindly by two investigators and compared to tumor and patient characteristics and outcomes.

RESULTS

A total of 231 patients had archived formalin-fixed, paraffin-embedded tumor tissue available and were included on the TMA. Mean age at diagnosis was 44 years (range 6-82 years); proportion of patients with female sex was (72%); 2015 American Thyroid Association (ATA) risk stratification was low (26%), intermediate (32%), and high (42%). BRAF V600E mutation was found in 74% of specimens, and IHC was scored as positive for RET (61%), MAPK (dpERK) (14%), PPARγ (27%), and pAKT (39%). Positive RET staining was associated with a lower risk of recurrence (HR = 0.46, 95% CI 0.22-0.96). No other molecular biomarkers were independent predictors of recurrence on univariable analysis. On RPA, patients with RET-negative and either MAPK(dpERK)-positive or pAKT-positive tumors were identified to have a high risk of recurrence (HR = 5.4, 95%CI 2.5-11.7). This profile remained associated with recurrence in a multivariable model including ATA risk stratification (HR = 2.8, 95% CI 1.3-6.0).

CONCLUSION

Characterization of molecular pathways involved in cPTC tumorigenesis may add further risk stratification for recurrence beyond the 2015 ATA risk categories alone.