(Ivanhoe Newswire) -- Researchers say they have found clues to molecular
markers on breast tumors that may predict which cancers will metastasize to the
lymph node system.
Predicting breast cancer spread from a sentinel lymph node removed during
surgery can be a hit or miss affair, and false negatives are a problem. When a
node is analyzed under a microscope, even though it appears clean of cancer
cells, metastasis can still occur in the patient. The sentinel node is the first
lymph node in the axilla to which the cancer spreads.
In a pilot study comparing genomic alterations in both breast cancer cells and
sentinel lymph nodes removed from 15 patients whose cancer had spread to the
lymph nodes, researchers found genes that were altered in both samples. These
alterations affected genes that function as either oncogenes or tumor
suppressors. The goal is to be able to determine, when a patient has a routine
biopsy of her tumor at the time of the diagnosis, who is at higher risk for
developing lymph node metastasis, according to Luciane Cavalli, Ph.D., assistant
professor of oncology at Lombardi.
"To our knowledge, very few studies have looked specifically for genomic
alterations in sentinel nodes in comparison to the primary tumor from the same
patient," Dr. Cavalli was quoted as saying. "If we find markers that can be
significantly associated with patients who develop axillary metastasis, we can
check for these markers at an early stage of the cancer management, before
axillary lymph node metastasis develops. That will give physicians a chance to
treat what is otherwise an unseen metastasis."
Currently, a sentinel lymph node is removed at the time the patient undergoes
surgery to remove breast tumors, and the node is examined for evidence of cancer
cells while the operation is in progress. If malignant cells are seen,
additional nodes in the axilla are removed, explained Dr. Cavalli. "This
procedure is performed during the surgery, and the methods currently used to
look for tumor cells in these nodes are not ultra sensitive, and may therefore
miss these malignant cells especially in the case of micrometastasis."
Dr. Cavalli and her team first screened the genomes of cells from both tumors
and nodes from the same patient using comparative genome hybridization (CGH),
and found that most of the genomic regions affected were similar in both of the
samples. They used microarray technology (array-CGH) to identify the genes
altered in these regions and found several that were altered in patient lymph
nodes and tumors. Some of these genes are well known, such as the growth
promoting gene her2neu, and the tumor suppressor BRCA1.
"It differed between patients -- in some, BRCA1 was missing in both samples, in
others, her2neu or other genes were amplified," said Dr. Cavalli.
"If we can use these genomic markers to identify tumor cells in the sentinel
lymph node to reduce the false negative rates that now exist in sentinel node
biopsy,” said Dr. Cavalli, “we can advance one step forward in patient care."
SOURCE: Presented at the American Association for Cancer Research (AACR)
Annual Meeting, April 18, 2010
