Necessary to remove all lymph nodes?

12 years ago (age 47) I had a lumpectomy and the lymph nodes were removed from my armpit. I had chemotherapy, radiation, and took tamoxifen for 5 years. A month ago I had a lumpectory in my other breast which turned out to be cancerous. I returned to have the sentinel node removed and just learned that it was cancerous. Now the surgeon wants to remove the remaining lymph nodes. I'm a little worried about getting lymphedema, although I haven't had any as a result of my surgery 12 years ago. Should I have all of the lymph nodes removed? Some of them? Are radiation and chemotherapy likely to eliminate any cancer that may remain in the lymph nodes?

[Cleveland Clinic]

Dear Levy60, Checking the lymph nodes for possible spread of cancer is part of the process of staging.  This information helps to determine recommendations for treatment.   There are situations in which additional treatment to the area (radiation) might be recommended if cancer has spread to 4 or more lymph nodes.   As the sentinel lymph node removed contained cancer cells, knowing if there was additional disease in the other lymph nodes under the arm would help in the treatment recommendations.   You would want to discuss the particulars of your case with your surgeon who can put their recommendations for further surgery into context of your individual situation.