Radioactivity thresholds for sentinel node biopsy in breast cancer

Aims The aim of the present study is to clarify the level of radioactive lymph node should be biopsied after the most radioactive SN is removed. Methods SNB using radionuclide was performed in our hospital for 1179 primary breast cancers between April 2000 and October 2005; most (1177/1179) were performed successfully. Our criterion for harvesting SNs is to remove tissue until no radioactive site is present. The level of radioactivity and the order of removal of each lymph node were compared with pathologic results. Results More than 2 (overall average 1.9) radioactive SNs were biopsied in 686 of 1177 breasts. Cancer positive results were recorded for 142 breasts with multiple SNs. In 142 breasts, 64 showed metastasis to the most radioactive node only, 39 showed metastasis other than the most radioactive node only, and 39 showed the most radioactive node and other radioactive nodes. Moreover, if several other criteria were applied, false-positive cases were increased significantly. Conclusions It is necessary to harvest radioactive lymph nodes other than the most radioactive. Moreover, efforts to remove every radioactive lymph node will minimize false-negative results.