Breast Cancer Lymph Node Biopsy May Need Closer Look
Wednesday, April 9, 2008; 12:00 AM
WEDNESDAY, April 9 (HealthDay News) -- A new long-term analysis of breast cancer patient survival suggests it might be time to update the way pathologists test lymph node biopsies.
A team of New York City physicians found about one in four patients originally declared to be free of cancerous cells in their sentinel lymph nodes were actually not cancer-free, and that tiny cancer remnants called micrometastases reduced the women's survival over a 20-year period.
These findings address a long-standing question among breast cancer researchers: Are such micrometastases prognostically significant?
"This is the first study to show that there is a survival impact for the detection of micrometastases," said Dr. Stephen F. Sener, a professor of surgery at Northwestern University Feinberg School of Medicine in Chicago.
The results are published in the April 10 issue of theJournal of Clinical Oncology.
In the study, a team led by Dr. Hiram S. Cody III, a professor of clinical surgery at Memorial Sloan-Kettering Cancer Center in New York City, analyzed a population of 368 patients who were originally diagnosed with breast cancer in the 1970s. At the time, these patients were judged to be free of cancerous cells on the basis of a single tissue slice (standard procedure at that time). As a result of that diagnosis, these patients received no follow-up treatment for their disease.
Each of these patients was then monitored over the following 20 years or so. Cody and his team retrospectively reanalyzed the decades-old tissue samples using modern techniques. They then assessed how many of the slices did, in fact, contain cancerous cells, and whether those stray cancerous cells had affected the women's survival.
"What we found was that among these patients, 23 percent were converted to node-positive [cancer status], and among those who were converted, their survival was worse than among patients who remained node-negative," said Cody.
"The 23 percent number is very significant, because it argues that if pathologists just do one section, you may want to ask them to do more," he explained. "We think the information you get by doing more is significant."
According to Cody, 30 years ago the standard of care for breast cancer patients was complete dissection of the axillary lymph nodes (those found under the armpit) followed by cell-shape analysis using a single tissue slice from each node. Such a surgery would typically collect 15 to 20 nodes, on average. Today, however, a different, less traumatic approach called sentinel node biopsy is used.
In sentinel lymph node (SLN) biopsy, a patient's tumor is injected with a combination of dye and radioactive tracer molecules. The following day, only those lymph nodes to which the tracer molecules migrated (the SLNs) are biopsied and analyzed. So, instead of harvesting 15 to 20 nodes, on average only two are three are collected using the new technique.
That reduction in work per node has a real payoff, because pathologists can delve much deeper into each sample, Cody explained.