Micrometastases Affect Breast Cancer Prognosis
Among women with early breast cancer, those with very small areas of cancer (micrometastases) in the axillary lymph nodes tend to have a higher risk of recurrence than those whose lymph nodes are completely free of cancer. These results were published in the Journal of Clinical Oncology.
Evaluation of the axillary (under the arm) lymph nodes for the presence of cancer is an important part of breast cancer staging. To assess the axillary lymph nodes, a surgeon will perform either an axillary lymph node dissection, in which many lymph nodes are surgically removed and evaluated, or a less extensive procedure known as a sentinel lymph node biopsy.
For some women, evaluation of the lymph nodes will reveal very small areas of cancer. Areas of cancer that measure between 0.2 mm and 2.0 mm are referred to as “micrometastases.” Even smaller areas of cancer are referred to as “isolated tumor cells.” The clinical significance of lymph node micrometastases and isolated tumor cells has been uncertain but was evaluated in a study conducted in Sweden.
The study collected information about the treatment and outcomes of 3,369 breast cancer patients. A total of 2,383 were node-negative, 107 had isolated tumor cells in the axillary lymph nodes, 123 had micrometastases, and 756 had macrometastases (larger areas of cancer in the lymph nodes).
- Five-year survival without cancer recurrence was 87.1% among women with no lymph node metastases, 88.9% among women with isolated tumor cells, 79.6% among women with micrometastases, and 80.1% among women with macrometastases.
- Compared with node-negative women, overall survival was not significantly worse among women with micrometastases or isolated tumor cells, but was worse among women with macrometastases.
These results suggest that women with lymph node micrometastases have a higher risk of breast cancer recurrence than women with cancer-free lymph nodes. Isolated tumor cells in the lymph nodes did not appear to affect outcomes in this population.
Reference: Andersson Y, Frisell J, Sylvan M, de Boniface J, Bergkvist L. Breast cancer survival in relation to the metastatic tumor burden in axillary lymph nodes. Journal of Clinical Oncology [early online publication]. May 10, 2010.
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