BRAFV600E status and clinical characteristics in solitary and multiple papillary thyroid carcinoma: experience of 512 cases at a clinical center in China
© Zheng et al; licensee BioMed Central Ltd. 2012
Received: 17 November 2011
Accepted: 8 June 2012
Published: 8 June 2012
Papillary thyroid carcinoma (PTC) is one of the most frequent endocrine malignancies. In most cases, it often presents as multifocal tumor. It has been reported that multifocal tumors are associated with elevated risk of lymph node and distant metastases. Multifocality is also one of the factors predicting prognosis. Recent studies show that BRAFV600E mutation occurs more frequently in aggressive PTC. The purpose of this study was to evaluate BRAFV600E status and clinicopathological features in multiple and solitary PTC.
We performed a retrospective study to analyze 512 PTC cases who received surgery, including 376 solitary PTCs and 136 multiple PTCs.
Multiple PTC is more related to lymph node metastasis and vascular invasion than solitary PTC. However, the distant metastasis rate and 10-year survival rate showed no difference between these two groups. BRAFV600E mutation status was more frequent in multiple PTC patients with lymph node metastasis and late stage at diagnosis.
BRAFV600E mutation is most commonly associated with extra-thyroidal extension and lymph node metastasis in PTC. Multiple PTC patients with young age, large tumors and BRAFV600E mutation should be followed carefully. Our study provides useful information for PTC patients’ followup and treatment.
KeywordsPapillary thyroid carcinoma Multiple PTC Solitary PTC BRAFV600E mutation
Thyroid cancer is the most common endocrine neoplasm, and one of the leading causes of death in patients with endocrine cancers [1, 2]. The incidence of thyroid cancer is increasing more rapidly than other cancers in both the United States  and other countries . Papillary thyroid carcinoma (PTC) is the most frequent type of thyroid cancer and represents one of the most frequent endocrine malignancies [5–7], it originates from the follicular cells of the thyroid. Surgery can cure most well-differentiated thyroid cancer when diagnosed and treated in early stage before the establishment of local or distant metastases. However, there are still some patients with well-differentiated thyroid cancer that die of the disease.
PTC is often present as multiple tumors [8, 9]. Postsurgical pathologic analysis has shown that 18% to 87% of PTC have multiple noncontiguous tumor foci in the individual glands, with a dominant tumor and multiple additional smaller foci of microcarcinomas [10, 11]. Studies have also reported that “multiple” tumors arising from metastasis of a single primary carcinoma origin, and “multicentricity” tumors arising independently from different origins in a context of genetic and/or environmental predisposition [12–14]. Some clinical factors have been used to predict which patients with thyroid cancer might have worse prognosis. Factors such as older age (>45 years old), male gender, certain histologic subtypes (i.e. tall cell, columnar cell and diffuse sclerosing variants of PTC), tumor size greater than 4 cm and presence of extrathyroidal extension are associated with neck recurrences and distant metastases [15–18]. In addition, multiple PTC is associated with increased risks of metastases and regional recurrences [19, 20]. Intra-glandular dissemination from the dominant tumor may serve as an indicator of metastatic potential and more aggressive phenotype.
The B-type Raf kinase (BRAF) mutation is the most common genetic alteration in papillary thyroid cancer (PTC). Of the three forms of Raf kinase, BRAF is the most potent activator of the mitogen-activated protein kinase (MAPK) pathway, which plays a major role in the regulation of cell growth, division, and proliferation . An activating mutation of BRAFV600E has been found in 36% to 69% of patients with PTC. This mutation is very prevalent in PTC and is frequent in the tumors in late stages (stages III and IV) of PTC [22, 23], with lymphovascular invasion and metastases [24, 25]. However, other studies did not find any association between BRAFV600E mutation and tumor stage, local invasiveness and lymph node metastasis .
The purpose of this study was to evaluate the clinicopathologic features with multiple and solitary PTC, and found that the status of BRAFV600E mutation in multiple PTC and solitary PTC.
Clinicopathological Characteristics of 512 cases of PTCs
Number of patients
Mean age (yr) ± SD
43.5 ± 16.4 (4–78)
Mean size (cm) ± SD
1.58 ± 1.35
Less than 1 cm
1 cm - 2 cm
2 cm – 4 cm
More than 4 cm
Lymph node metastasis
Treatment and follow-up of PTC
The patients were treated with thyroidectomy in the Department of head and neck. The initial treatment was lobectomy and total/ near total thyroidectomy, central neck and/or lateral-cervical lymph node dissection when necessary,. (According to the National Comprehensive Cancer Network (NCCN), 1995) Tumor samples were obtained in accordance with protocols approved by the institutional review board, and informed consent was achieved 1 day before surgery together with the surgical one.
Histological diagnosis was made independently, in a blinded fashion, by two pathologists. Tumors were classified according to the histopathological typing of the World Health Organization. The multifocal or solitary tumor was identified by pathologist. A concordance rate of 98% was obtained between the two pathologists. The few discordant cases were discussed with a third pathologist.
131I postoperative administration was performed for thyroid remnant ablation when the patient received total or near-total thyroidectomy, L-thyroxine (L-T4) suppressive therapy. Additional 131I therapies were given to treat local recurrences or distant metastases that were not removable by surgery. The patients was performed cervical ultrasound and TSH-suppressed thyroglobulin 6 months after treatment, the anti-throglubulin antibody and T3, T4, TSH, serum thyroglobulin was measured after thyroxine withdrawal or rhTSH stimulation approximately 12 months after the ablation to verify absence of disease.
Criteria for disease remission were negative for 131I Whole Body Scanning (WBS) and Tg < 2 ng/mL after L-T4 withdrawal or recombinant thyroid-stimulating hormone injection. The diagnosis of recurrence was made after observing an elevation of Tg levels associated with focal areas of 131I uptake at WBS and/or evidence of lesions at ultrasound or computed tomography (CT) and/or positive cytology examination. 435 patients were followed up by reviewing the clinical records for 10 years or to the death of patients. 46 patients were dead in 10 years, 77 patients were lost of follow up.
Tumor sample preparation and examination
Specimens from surgery were cut and fixed in 10% formalin for preparing paraffin-embedded sections and stained with hematoxylin and eosin (H & E) for histologic examination. One to 3 representative sections of the tumor and all suspicious lesions were submitted for microscopic examination by two endocrine pathologists. The diagnosis of PTC was based on characteristic architectural features, including the presence of true papillae and/or characteristic nuclear changes, such as ground glass nuclei, nuclear pseudoinclusions, and nuclear grooves.
Detection of BRAFV600E mutation
DNA was extracted from paraffin-embedded tissue. Briefly, unstained tumor tissues on 20-mm-thick sections were chosen by comparing to H & E-stained sections. For larger tumors, the marked areas were deparaffined and tissues were collected. For small tumors, laser-capture microdissection was performed to collect tissues. Samples from large tumors were incubated in TE9 (0.5 M TRIS, 0.2 M EDTA, 0.01 M sodium chloride, and 1% sodium dodecyl sulfate; pH 9.0) and 0.2 mg/ml of proteinase K for 4 days at 55°C. Small tumor samples in Laser-capture microdissection caps were incubated in TE9 for 2 days at 37°C. Fresh proteinase K was added daily. Samples were centrifuged and supernatants were subjected to digestion for two additional days at 55°C. Chelex 100 resin (Bio-Rad) was added to each sample and incubated for 1 hour and the supernatant was removed. DNA was extracted using phenol–chloroform and concentrated by ethanol precipitation. DNA was resuspended in TRIS–EDTA (10 mM TRIS hydrochloride and 1 mM EDTA; pH 8.0).
DNA samples were applied for PCR analysis using the following primers: BRAF 11F (5′-TCCCTCTCAGGCATAAGGTAA-3′) and BRAF 11R (5′-CGAACAGTGAATATTTCCTTTGAT-3′; PCRproduct, 312 bp) for exon BRAF11, and primers BRAF 15F (5′-TCATAATGCTTGCTCTGATAGGA-3′) and BRAF 15R (5′-GGCCAAAAATTTAATCAGTGGA-3′; PCR product, 223 bp) for exon BRAF 15.
Cycle sequencing of the purified PCR products was performed by using one of the PCR primers and the big dye terminator sequencing kit (Applied Biosystems, Foster City, CA). The Sephadex G-50–purified cycle sequencing products were analyzed using an ABI PRISM 310 Genetic Analyzer (Applied Biosystems).
Statistical analyses were performed with SPSS software (version 11.0; SPSS Inc., Chicago, IL). Chi-square or Fisher exact tests were used to compare frequencies between groups. All data were expressed as means ± SD. Differences between group means were compared by the independent sample Student t-test or the Mann–Whitney U-test. P value < 0.05 was considered statistically significant.
Results and discussion
Comparison of progression between patients with solitary and multiple PTC
Papillary thyroid carcinomas represent about 90% of all thyroid cancers and tumor incidence has been increasing in recent decades [2, 10]. Although PTC patients generally respond in a favorable manner and have a favorable prognosis, many develop recurrence and some die from this disease. Pathological analysis of patients with PTC undergoing surgical treatment have shown that the incidence of multiple noncontiguous tumor foci in individual glands is high [27, 28]. Thus, we evaluated progression of disease between patients with solitary and multiple PTC.
Large tumor size, age, gender, extra-thyroidal invasion, lymph node and distant metastasis, and the variant of the PTC are the main determinants for poor prognosis in PTC patients.
Comparison of progression between patients with solitary and multiple PTC
Mean age (yr) ± SD
44.3 ± 15.1
42.5 ± 17.4
Mean size (cm) ± SD
1.29 ± 1.44
1.67 ± 1.15
Tall cell variant
Lymph node metastasis
10-year survival rate
Clinical parameters in multiple PTC patients in the presence or absence of lymph node metastasis
Lymph node metastasis
41.5 ± 12.2 (9–60)
50.3 ± 14.2 (18–75)
Tumor diameter (mm)
2.08 ± 1.51
1.13 ± 1.36
In patients with surgical treatment for PTC, pathological analysis commonly identifies multiple noncontiguous tumor foci in individual glands. Estimates of the frequency of such multiple tumors vary, between 18 and 87 percent depending on the techniques used. Multiple tumors have been associated with increased risk of lymph node and distant metastases, persistent local disease after initial treatment, and regional recurrence . Therefore, our results are consistent with previous reported studies that patients with multiple PTC associate with increased risk of lymph-node metastases and regional recurrence. However, in this study, distant metastasis did not significantly differ. All these findings suggest that patients with multiple papillary thyroid cancer should receive aggressive treatment. According to the guideline by American Joint Committee on Cancer (AJCC) (Table 2). An association can be made when comparing tumor stage in patients with solitary and multiple PTC. More stage III/IV cases were found in multiple PTC patients compared to those in solitary PTC patients. Consistently, the number of patients with stage I is higher in solitary PTC patients than that in multiple PTC.
BRAFV600E mutational status and clinicopathologic characteristics in 512 patients of PTC
BRAFV600E is the most prevalent genetic alteration implicated in the initiation and progression of PTC, especially in aggressive subtypes such as the tall cell variant of PTC and in those with extra-thyroidal extension and lymph node or distant metastases. The mutation has been associated with both radioactive iodine refractoriness and PTC recurrence. Xing et al. [33, 34] have reviewed studies of the association between the BRAFV600E mutation and clinicopathologic characteristics in PTC. In a review of 12 studies with a total of 1,168 patients. Lee et al. [35, 36] reported that the BRAFV600E mutation was detected in 49% (570/1,168) cases. Recent studies report a varying prevalence of the mutation in PTC, ranging from 29 to 83%.
BRAF V600E mutational status in 512 patients of PTC
45.4 ± 12.3
40.8 ± 16.2
Male/ Female ratio
Many other studies have found that the BRAFV600Emutation is most commonly associated with extra-thyroidal extension, lymph node metastasis, and advanced disease stage.  Our data also found a significant association between the BRAFV600E mutation and extra-thyroidal invasion and lymph node metastasis. This study also showed that the BRAFV600E mutation correlated with male gender and elder age.
Correlation between clinicopathological characteristic and BRAF V600E mutation in solitary PTC and multiple PTC
BRAFV600E mutation patients
solitary PTC (188)
multiple PTC (75)
Less than 45
45 or older
Lymph node metastasis
Comparison of the effects of BRAFV600E mutation on progression in multiple PTC patients
The multiple foci in papillary thyroid carcinoma is a common clinical finding, but the origin of these foci is ambiguous. Despite attempts to establish whether multiple intra-thyroidal tumors are metastases of a primary thyroid tumor or arise independently, the question remains unresolved. Evidence from previous studies has lent support to both arguments. We analyzed whether multiple intra-thyroidal tumors were metastases of a primary thyroid tumor cell or arise independently from different tumor cells, and effects of tumor foci origin on disease progression. We assessed the origin of multiple PTC by analyzing the BRAFV600E mutation status in the multiple PTC. The status of the BRAFV600E mutation was heterogeneous (35 mixed BRAFV600E mutation status of 75 BRAFV600E mutation multiple PTC) in 46.7% cases, suggesting at least some of multiple PTC arise as independent tumors. It’s difficult to study whether those with same BRAF change are from the same origin, since BRAF is a hot spot mutation and many cases have the same change just by chance. It should be noted that the possibility cannot be excluded that tumors with or without BRAFV600E mutation in PTC have a unique clonal origin, because BRAFV600E mutation is a common genetic alteration in PTC and more than one tumor foci may have this mutation at the same time. In our study, 46.7% multiple PTC are heterogeneous.
Studies have showed that BRAFV600E mutation was significantly more frequent in multiple PTC patients with extra-thyroid invasion, and lymph nodes metastasis. These observations indicate that BRAFV600E mutation may be a predictor of tumors with high aggressiveness [38–40]. Therefore, we evaluated the status of BRAFV600E mutation in progression of multiple PTC patients. In these 136 patients with multiple PTC, 40 patients (29.4%) had BRAFV600E mutation in all foci, 61 patients (44.9%) patients showed negative for BRAFV600E mutation in all foci, and 35 patients (25.7%) showed mixed status for BRAFV600E mutation (BRAFV600E mutation positive and negative tumor foci coexisted in the same patient). When we analyzed BRAFV600E mutation status in multiple PTC, we found that BRAFV600E mutation mixed status was more frequent in patients with more than 4 tumors compared with patients with 2 or 3 tumors.
The effects of BRAF V600E mutation on progression in multiple PTC patients
Age ≤ 14
Tall cell variant
Lymph node metastasis
10-year survival rate
In conclusion, we showed in this study that late stage tumors, lymph node metastasis and vascular invasion in multiple PTC patients are more frequent than those in solitary PTC patients. In patients with multiple PTC, the status of lymph node metastasis was related to the early age at diagnosis, the larger tumor, extra-thyroidal invasion, and BRAFV600E mutation status. Therefore, multiple PTC patients with young age, large tumors and BRAFV600E mutation should be treated and follow-up carefully.
Papillary thyroid carcinoma.
The authors would like to thank Prof. Baocun Sun in Tianjin Medical University Cancer Institute and Hospital for providing materials, the members of Dr. Gao’s department for their assistance in the discussion, and Dr. Yan F, Professor, Venderbilt university school of medicine, Dr. Jiao Y, John Hopkins Kimmel Cancer center for scientific and language editing.
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