Gaining a Better Understanding of Cancer in the Sentinel Lymph Node

When breast cancer spreads, it often appears first in the sentinel node—the first node to which the tumor drains. Removing only the sentinel node to check for cancer is a relatively new technique. By using this approach, if the sentinel node is clear of cancer, the surgeon will not remove the rest of the axillary lymph nodes, sparing the patient side effects like lymphedema (swelling of the arm) and numbness of the arm. However, this sentinel node biopsy technique raises new questions. Does finding a minimal amount of cancer in the node actually matter? And if it does matter, what’s the best way to treat those patients?

In an effort to provide some direction, researchers examined pathology reports of more than 5,600 women and identified nearly 1,400 with positive sentinel nodes. Among women with breast cancer that has spread to the sentinel lymph node, drug therapy after axillary lymph node dissection, or removal of the lymph nodes in and around the armpit, reduced their risk of death by 78 percent and improved their chances of living without a recurrence by 76 percent, according to a study presented at the San Antonio Breast Cancer Symposium. After a median follow-up of almost eight years, poor histologic tumor grade—how abnormal the cells look under the microscope—and larger size (more than 2 mm) of the errant tumor were the most accurate predictors for worse survival. Interestingly, the treatment benefit in disease-free survival was particularly pronounced in middle-aged women, with very young and very old women having a higher risk of a recurrence.

In another study presented in San Antonio, researchers found a nearly four-fold increase in isolated tumor cells in the sentinel node in women who had prior surgical excision of the tumor compared with those who did not. Although this suggests the procedure results in displacement of cancer cells, investigators found no spread to other lymph nodes. Researchers concluded that for isolated tumor cells found in the sentinel node after an earlier surgical excision biopsy, axillary lymph node dissection may not be needed.