Jan. 6, 2000 (NEW HAVEN) -- Yale Cancer Center Researchers are the first to show a link between the number of lymph nodes in breast cancer patients and their chances of long-term survival. In a retrospective study published in the January 1 issue of the journal Cancer, an inverse correlation was shown between the number of lymph nodes in the axilla, or armpit, of breast cancer patients and their 5-year survival rates.
The findings demonstrate that patients with no evidence of breast cancer spread to the lymph nodes but with 20 or more lymph nodes, had a 4.33 times greater relative risk of dying of metastatic breast cancer after five years than patients who had fewer than 20 lymph nodes. (Metastatic cancer is that which has spread to other parts of the body.) The five-year survival rate for patients with 20 or more tumor-free lymph nodes was 84.7%, compared to 96.3% for patients with fewer than 20 tumor-free lymph nodes.
"The strong association between aggressive tumor growth and elevated lymph node number raises the possibility that some tumors stimulate lymph node enlargement, making it easier to detect an increase in the number of lymph nodes," said David L. Rimm M.D., Ph.D., assistant professor of pathology and co-author of the study. "Furthermore, the association with decreased survival suggests that tumors that grow aggressively stimulate lymphatic drainage, thus providing a route for cancer to spread from the primary lesion."
Spread of breast cancer to the lymph nodes is the oldest and most reliable indicator of disease outcome. Physicians typically note both the number of tumor positive lymph nodes and the total number of lymph nodes in breast cancer patients. Even without evidence of lymph node involvement, approximately 10-15% of breast cancer patients will ultimately die from the spread of the disease beyond the primary tumor. While previous studies have demonstrated the relationship between the number of tumor-positive lymph nodes and poor prognosis, none have shown a relationship between the total number of lymph nodes and the chances for survival.
"Our goal was to determine whether this readily available but commonly overlooked number has value in predicting the outcomes of lymph node-negative breast cancer patients," said Rimm. "While further studies are called for, this research provides clinicians with one more piece of prognostic information, and may suggest more aggressive therapy in patients with high numbers of axillary nodes."
Collaborating with Rimm were Robert L. Camp, M.D. of the Yale University School of Medicine, and Eric B. Rimm, D.Sc., associate professor of nutrition and epidemiology, Harvard School of Public Health. The scientists studied retrospectively 290 patients with lymph node negative breast cancer, who underwent breast resection at Yale-New Haven Hospital from July 1, 1983 to July 1, 1993. Patients were followed until their death or until the end of the study in July, 1999.
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