I was diagnosed with cancer of unknown primary. I had 2 cancerous lymph nodes (out of the 47 removed) under my arm. The oncologist believes that the cancer came from the breast although there is no tumor in the breast. The oncologist would like me to have a mastectomy after my scheduled chemotherapy but I am apprehensive. My surgeon said that the chemo will kill any remaining cancer in my body. The only advantage I see to the mastectomy is that the cancer cannot return to the breast although it can still return to other parts of my body. Has anyone else experienced this? If so, what did you do?