An axillary lymph node dissection is when doctors remove most or all of the lymph nodes in the armpit. The procedure may be done if cancer is found in the sentinel nodes. The number of lymph nodes in the armpit varies from person to person but is usually between 15 and 30. In women found to have cancer in their lymph nodes before surgery, giving chemotherapy before surgery is a way to reduce the likelihood of needing an axillary dissection.