Diseases (14)

Diagnostic Testing (12)

Note:

Note:

To evaluate for resistance to anti-EGFR therapy in colorectal cancer.


Note:

To evaluate for resistance to anti-EGFR therapy in colorectal cancer.


Note:

Highly specific in papillary thyroid carcinoma.


Note:

Highly specific in papillary thyroid carcinoma.


Note:

Rule out Lynch syndrome in people who show loss of MLH1 IHC staining on colorectal tissue.


Note:

Rule out papillary thyroid carcinoma.

Overview

B-RAF is an oncogene belonging to the RAF family of serine–threonine-specific protein kinases, downstream of the epidermal growth factor receptor (EGFR) and the RAS family of small G-proteins (KRAS, HRAS, and NRAS) in the MAPK pathway. More than 30 mutations of the BRAF gene associated with human cancers have been identified. These mutations make the B-RRAF oncogene active, continuously sending signal downstream to the MAPK pathway, which then results in cell proliferation. The most common mutation is the missense mutation in codon 600 of exon 15 located on chromosome 7. BRAF mutations are most often found in melanoma (80%), colorectal cancer (5%), lung cancer (3%), ovarian cancer, and thyroid gland cancer. They are also found in lower prevalence in some other cancers such as acute myeloid leukemia, glioma, sarcomas, breast cancer, and hepatoma. More than 90% of mutations are the V600E (1799T>A) mutation. Recent studies have shown that metastatic colorectal cancer patients with this BRAF mutation do not have a strong response to anti-EGFR therapies such as cetuximab and panitumumab. This assay detects any amino acid change that has an A nucleotide at position 1799 in exon 15 of the BRAF gene regardless of any other common changes (could detect V600E/V600K/V600D), allowing identification of patients who are likely to benefit from such treatment.
The presence of somatic mutation in the B-RAF gene product, located downstream of EGFR signaling, has been shown to serve as a biomarker for poor prognosis and poor response to anti-EGFR cancer therapy in cancer patients.
Treatment of certain types of cancer with drugs targeted specifically at the EGFR receptor work only if there is no mutation of the EGFR pathway, which incldes BRAF. Therefore, before starting such therapy, analysis for EGFR family mutations is required. In fact, insurance companies do require this. Also BRAF is related to microsatellite instability status such that BRAF V600E positivity is unlikely to be a MLH1 mutant. In thyroid papillary carcinoma, BRAF mutation results in an aggressive phenotype so that knowledge of this status aids in treatment planning and recurrence risk assessment. 30 - 40% of papillary thyroid cancers are BRAF mutation positive. Treatment with MEK inhibitors may be useful in this group. About 35-45% of melanomas are BRAF muatation positive and this mutation is present in non-malignant nevi so that early detection may be possible. Melanomas with BRAF mutation are also sensitive to MEK inhibitors. 10-20% of ovarian cancers are positive for either BRAF or KRAS mutation, mostly low grade non-serous types.

Clinical Utility

  • Determining eligibility of and monitoring treatment with anti-EGFR therapy (cetuximab and panitumumab)
  • As an aid in diagnosis and management of melanoma
  • As an aid in diagnosis and management of colorectal cancer
  • As an aid in diagnosis and management of lung cancer
  • As an aid in diagnosis and management of thyroid cancer
  • Therapy monitoring and disease management

Interpretation

  • If either the BRAF V600E mutation or MLH1 promoter methylation is found in a microsatellite unstable tumor, then the tumor is probably sporadic and further work-up for HNPCC may not be warranted.
  • If no BRAF mutation or MLH1 methylation is found, then the tumor may be either sporadic or inherited, and further work-up for HNPCC is recommended. It is known now that the BRAF p.V600E mutation is detected in more than 70% tumors with loss of MLH1 due to promoter hypermethylation but is rarely detected in tumors with a germline MLH1 gene mutation. Thus, a germline mutation within the MLH1 gene is very unlikely in this case.
  • When testing is performed for therapeutic selection, especially for the efficacy of EGFR-targeted therapies in colorectal cancer, tumors lacking KRAS and BRAF might not be the best choice and may have limited therapeutic value for this patient.
  • Detection of BRF V600 mutation in melanoma might indicate good respond to BRAF targeted therapy.

    Positive :

  • Melanomas
  • Colorectal cancer
  • Lung cancer
  • Ovarian cancer
  • Thyroid gland cancer
  • Acute myeloid leukemia
  • Glioma
  • Sarcomas
  • Breast cancer
  • Hepatoma

Reference Ranges

Mutation not detected (Negative for mutation analyzed)
 

 

Methodology

Amplification refractory mutation system (ARMS), or real-time PCR detection method with single nucleotide extension, Chip array technology with allele specific primer extension, Pyrosequencing, conventional sequencing

Specimen Collection

Formalin fixed paraffin embedded (FFPE) tumor samples. Microdissection is recommended for better sensitivity and specificity. This would increase the fraction of tumor cells in the sample as it allows capture of the tumor cells. The presence of normal cells that carry wild type alleles can dilute the tumor cells, and dilution by normal and inflammatory cells might impact the sensitivity of mutation detection.

In colorectal cancer DNA can be also isolated from stool samples obtained from patients with colorectal cancer.

In lung cancer, sputum can be used for isolation of DNA from cancer cells.

Additional Testing

K-ras Gene Mutation Detection, Cytokeratin 8/18 Low Molecular Weight (CAM 5.2) by IHC (for melanoma), KIT Mutations (for melanoma), NRAS Mutation Detection (for melanoma), Microsatellite Instability/HNPCC by molecular method and by IHC (for colon cancer), Septin 9 (SEPT9) for colon cancer, Methylated DNA Detection by Real-Time PCR (for lung cancer), EGFR by FISH (for lung cancer), EGFR Mutation Detection by molecular method, p53 by molecular method and by IHC, Ki67 by IHC.

Turnaround Time

7-14 days

CPT

81210

LOINC

ICD10

C18Malignant neoplasm of colon
C18.2Malignant neoplasm of ascending colon
C18.4Malignant neoplasm of transverse colon
C18.6Malignant neoplasm of descending colon
C18.7Malignant neoplasm of sigmoid colon
C18.9Malignant neoplasm of colon, unspecified
C19Malignant neoplasm of rectosigmoid junction
C20Malignant neoplasm of rectum
C21Malignant neoplasm of anus and anal canal
C21.0Malignant neoplasm of anus, unspecified
C21.1Malignant neoplasm of anal canal
C21.8Malignant neoplasm of overlapping sites of rectum, anus and anal canal
C34Malignant neoplasm of bronchus and lung
C34.0Malignant neoplasm of main bronchus
C34.00Malignant neoplasm of unspecified main bronchus
C34.01Malignant neoplasm of right main bronchus
C34.02Malignant neoplasm of left main bronchus
C34.1Malignant neoplasm of upper lobe, bronchus or lung
C34.10Malignant neoplasm of upper lobe, unspecified bronchus or lung
C34.11Malignant neoplasm of upper lobe, right bronchus or lung
C34.12Malignant neoplasm of upper lobe, left bronchus or lung
C34.2Malignant neoplasm of middle lobe, bronchus or lung
C34.3Malignant neoplasm of lower lobe, bronchus or lung
C34.30Malignant neoplasm of lower lobe, unspecified bronchus or lung
C34.9Malignant neoplasm of unspecified part of bronchus or lung
C34.90Malignant neoplasm of unspecified part of unspecified bronchus or lung
C43Malignant melanoma of skin
C43.9Malignant melanoma of skin, unspecified
C56Malignant neoplasm of ovary
C71Malignant neoplasm of brain
C71.0Malignant neoplasm of cerebrum, except lobes and ventricles
C71.1Malignant neoplasm of frontal lobe
C71.2Malignant neoplasm of temporal lobe
C71.3Malignant neoplasm of parietal lobe
C71.4Malignant neoplasm of occipital lobe
C71.5Malignant neoplasm of cerebral ventricle
C71.6Malignant neoplasm of cerebellum
C71.7Malignant neoplasm of brain stem
C71.8Malignant neoplasm of overlapping sites of brain
C71.9Malignant neoplasm of brain, unspecified
C73Malignant neoplasm of thyroid gland
C78.0Secondary malignant neoplasm of lung
C82Follicular lymphoma
C82.89Other types of follicular lymphoma, extranodal and solid organ sites
C82.90Follicular lymphoma, unspecified, unspecified site
C82.99Follicular lymphoma, unspecified, extranodal and solid organ sites
C85.90Non-Hodgkin lymphoma, unspecified, unspecified site
D03Melanoma in situ
D34Benign neoplasm of thyroid gland
D3ABenign neuroendocrine tumors
D3A.8Other benign neuroendocrine tumors
E31.2Multiple endocrine neoplasia [MEN] syndromes
E31.20Multiple endocrine neoplasia [MEN] syndrome, unspecified
R91Abnormal findings on diagnostic imaging of lung
R97Abnormal tumor markers
R97.0Elevated carcinoembryonic antigen [CEA]
Z80.0Family history of malignant neoplasm of digestive organs
Z80.1Family history of malignant neoplasm of trachea, bronchus and lung
Z85Personal history of malignant neoplasm
Z85.0Personal history of malignant neoplasm of digestive organs
Z85.1Personal history of malignant neoplasm of trachea, bronchus and lung
Z85.118Personal history of other malignant neoplasm of bronchus and lung
Z85.820Personal history of malignant melanoma of skin
Z85.850Personal history of malignant neoplasm of thyroid
Z85.9Personal history of malignant neoplasm, unspecified

References