Sentinel lymph node is a group of nodes that the metastasizing cancer cells reach. Scientists have come up with a revolutionary technique that examines a large section of this node, which could be helpful in lowering the risk of recurring breast cancer and multiple surgeries.
The technique, known as GeneSearch Breast Lymph Node Assay is being used at the Medical College of Georgia, and examines half of the tissue in the sentinel lymph node.
The test is capable of examining more than 10 times the amount of tissue examined in traditional biopsies.
Dr. Zixuan (Zoe) Wang, molecular biologist and scientific director of MCG's Georgia Esoteric and Molecular Diagnostic Labs, L.L.C., said that because the test examines the tissue with molecular tools, it is more sensitive.
"When we look at the tissue with the GeneSearch test, we are looking for excessive amounts of mamoglobin and cytokeratin 19, both genes that are expressed more in breast cancer tissue," said Dr. Wang.
"If those genes are present in excessive amounts, we know the cancer has metastasised," he added.
Lumpectomy is a common surgical procedure designed to remove the breast tumour.
According to Dr. Stephen Peiper, chair of the MCG Department of Pathology and Georgia Cancer Coalition Distinguished Cancer Clinician and Scientist, the GeneSearch test uses molecular diagnostic methods to examine more tissue than traditional sentinel node biopsies, thus decreasing the chances of false negative results.
"During a traditional sentinel node biopsy, a surgeon would remove a node, then the pathologist would cut that section in half and cut that section to a quarter of the original sample size," said Dr. Peiper
"They then would cut wafer-thin slices from those sections, freeze and stain them, and look for cancer cells under a microscope.
"This technique, called frozen section, would be done during the lumpectomy surgery. If the tissue is positive for cancer cells, the surgeon removes more nodes from the patient, but if it is negative, the surgery is over," he added.
"If there are small amounts of cancer cells in the whole node, we may or may not see those with the traditional tests, because we only examine a small section of tissue," he says. "With this technology, we increase the chance of detecting them."
Dr. Scott Lind, professor and chief of the MCG Section of Surgical Oncology said that there is a higher false-negative rate with traditional sentinel node biopsies.
"If that happens, the patient has to come back in for another surgery to take out more lymph nodes that have likely harbored the breast cancer cells," he added.
The clinical trials of the new test correctly identified more than 95 percent of patients whose cancer had spread to their lymph nodes.