GeneSearch (TM)

Describtion
The GeneSearch™ Breast Lymph Node (BLN) Assay is commercially available a qualitative real-time gene-based assay for the rapid detection of sentinel lymph nodes¹ (SLNs) metastases larger than 0.2 mm in nodal tissue removed from sentinel lymph node biopsies of breast cancer patients.
Results from the test can be used by the doctor during surgery or after surgery, in deciding whether to remove additional lymph nodes.

Selection criteria

Analysed genesExpression of Mammaglobin (MGB1) and Cytokeratin 19 (KRT19) genes is analysed. Internal control gene - porphobilinogen deaminase (PBGD).

Sample preparation

Workflow

Test technology
Test is based on reverse-transcription and real-time polymerase chain reaction (RT-PCR) assay that detects metastatic tumor expression markers: Mammaglobin (MGB1) and Cytokeratin 19 (KRT19), which are present in higher level in breast cancer, but not in nodal tissue (i.e. tissue specific RNA expression). If groups of growing breast cancer cells (metastases) are in the lymph nodes, a strong fluorescent signal is produced for one or both of the gene products. Absence of such a signal means that metastases are not present. A third fluorescent signal, for a gene product that is abundant in normal lymph node tissue, indicates that a negative test result is correct.
The real time RT-PCR reaction is performed in a homogeneous, one-step, fully contained reaction with specially designed TaqMan® fluorescent probes. Producer recommends use of Cepheid SmartCycler® instrument.

Assay includes:

• The GeneSearch™ Breast Lymph Node (BLN) Test Kit
• The GeneSearch™ Breast Lymph Node (BLN) RNA Sample Preparation Kit
• The GeneSearch™ Breast Lymph Node (BLN) Protocol Software

Video

Clinical validation

Sensitivity, specificity, positive-predictive value

Limitations
The GeneSearch™ Breast Lymph Node (BLN) test may be used with sentinel lymph node biopsy for patients who have been informed about the risks, benefits and limitations of this test. True positive results may prompt the removal of additional lymph nodes during initial surgery. False positive results may lead to unneeded surgery and its associated risks. False negative or inconclusive test results may delay the needed removal of additional lymph nodes.
Though treatment for metastases larger than 2.0mm is widely accepted as beneficial, clinical studies have not yet provided data for a consensus on benefit from treatment based on very small breast cancer metastases (between 0.2mm and 2.0mm) in sentinel lymph nodes.

Price

Turnaround time

Ordering
By physicians only.

Producer

Footnotes

1. The sentinel lymph node is the hypothetical first lymph node or group of nodes reached by metastasizing cancer cells from a tumor. If the sentinel lymph node has breast cancer cells in it then an axillary dissection is usually warranted. If the sentinel lymph node is free of breast cancer cells than an axillary lymph node dissection can be avoided, sparing you of an increased risk for lymphedema.