Molecular-Based Lab Test Detects Metastatic Breast Cancer

A molecular-based laboratory test detects whether breast cancer has metastasized to nearby lymph nodes.

The assay detects molecules that are abundant in breast tissue but scarce in a normal lymph node. The presence or absence of breast cancer cells in underarm lymph nodes is a powerful predictor of whether the cancer has spread and is used to help decide appropriate therapy for a woman with metastatic breast cancer.

Called the GeneSearch BLN assay, it is manufactured by Veridex (Warren, NJ, USA), a Johnson & Johnson Company. In July 2007, the BLN assay was approved by the US Food and Drug Administration (FDA). "The GeneSearch BLN assay offers a new approach to sentinel node testing,” said Daniel Schultz, M.D., director of the FDA's center for devices and radiological health. "Results of this rapid test are available while patients are on the operating table, providing a way for some women to avoid a second operation.”

Lymph nodes are part of the system that helps protect the body against infection. The first lymph node that filters fluid from the breast is called the sentinel node, because that is where breast cancer cells are likely to spread first. During a lumpectomy or mastectomy to remove a breast tumor, surgeons commonly remove the sentinel node for examination under a microscope. Sometimes the sentinel node is examined immediately and if tumor cells are found, additional lymph nodes are removed. A more extensive microscopic examination, requiring one to two days for results, is almost always performed. If tumor cells are only found with the later microscopic examination, the patient may require a second surgery to remove the remaining lymph nodes.

In a clinical trial, the GeneSearch BLN assay showed strong agreement with results from extensive microscopic examination of the lymph nodes of 416 patients. The test accurately predicted that breast cancer had spread nearly 88% of the time in women with metastasis. Patients without metastasis were identified accurately 94% of the time.


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