Papillary Thyroid Carcinoma With Rare exon 15 BRAF Mutation Has Indolent Behavior: A Single-Institution Experience.

Papillary Thyroid Carcinoma With Rare exon 15 BRAF Mutation Has Indolent Behavior: A Single-Institution Experience.

J Clin Endocrinol Metab. 2016 Aug 29;:jc20161775

Authors: Torregrossa L, Viola D, Sensi E, Giordano M, Piaggi P, Romei C, Materazzi G, Miccoli P, Elisei R, Basolo F

Abstract
CONTEXT: Approximately 40% of papillary thyroid carcinomas (PTC) harbor the BRAF V600E mutation, which is significantly associated with the advanced clinico-pathological features of PTC at diagnosis, higher recurrence rate and disease-related mortality. BRAF alterations other than V600E are less common in PTC, and their clinical significance remains to be established.
OBJECTIVE: The aim of the study was to describe a large cohort of rare exon 15 BRAF alterations (r-BRAF), the clinico-pathological features of PTC harboring these alterations and to clarify their clinical significance.
METHODS: A total of 2,961 PTCs were collected from 2006 to 2013 and screened for exon 15 BRAF alterations.
RESULTS: Exon 15 BRAF alterations were found in 1,186 of 2,961 PTC cases (40.0%). In particular, we found the BRAF V600E mutation in 95.3% (1,131/1,186) and r-BRAF in 4.7% (55/1,186) of the 1,186 cases. r-BRAF were found in 18 microcarcinomas, 33 follicular variants, 1 classic variant and 1 trabecular/solid variant. The most frequent r-BRAF was BRAF K601E (35/55, 63.6%) followed by BRAF V600_K601delinsE (7/55, 12.7%) and BRAF T599I-V600_R603del (2/55, 3.6%). The remaining 11 alterations were found in one case only. The large majority of these tumors were unifocal (34/55, 61.8%), completely encapsulated (46/55, 83.6%) and intrathyroidal (53/55, 96.4%) with a low prevalence of lymph node metastases (1/55, 1.8%) and a less advanced tumor stage at diagnosis (AJCC stage I/II: 51/55, 92.7%).
CONCLUSIONS: r-BRAF are very uncommon in PTC and are found almost exclusively in PTC with low-risk clinico-pathological features.

PMID: 27571181 [PubMed - as supplied by publisher]

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