If you choose to join this study, you will have the lymph node with known cancer removed as well as sentinel nodes, to see if other lymph nodes also have cancer. Sentinel nodes are the first few lymph nodes to which cancer generally spreads. After this procedure, you will get a random assignment (like a coin flip) to 1 of 2 groups:

• Group A: If you are in this group, your remaining axillary (armpit) lymph nodes will be surgically removed. This corresponds to the standard treatment, which can effectively prevent recurrences in the armpit. However, about a quarter of people experience side effects, some of which are permanent.
• Group B: If you are in this group, your armpit will be irradiated without removing the remaining lymph nodes. Radiotherapy to the armpit is given at the same time as radiotherapy to the breast or chest, which is planned procedure for participants in both groups.