I had a different experience. I had two ( two tumors) radioactive injections into the nipple the day before unilateral mastectomy. It was used to trace the path of the cancer. They use a mini pen size Geiger counter to trace. I had one known positive sentinel node ( biopsy) before surgery and one micro invasion in another discovered at time of surgery. 5 next layer nodes were removed and were negative.

The nipple injections were the single most painful experiences I have ever had … but very quick recover and a great diagnostic tool.