But, the data did show that the women who did not have the dissections had worse survival rates than those who did. Breast-conserving surgery involves removing just the cancerous tumor without taking the entire breast.
Axillary nodes are lymph nodes found under the arm.
Axillary node dissections involve taking out roughly 15 of the innumerable lymph nodes through a small incision under the arm. Originally physicians thought that cancer spread from the local site to the regional lymph nodes and then to the rest of the body. By removing the lymph nodes, a surgeon might prevent the cancer from spreading. However, about 15 years ago, physicians started to believe that cancer spread systemically from the very beginning. The doctors thought that removing the lymph nodes just provided information about how bad the tumor was and didn't actually prevent the cancer from spreading.