[Interest of preoperative lymphoscintigraphy on sentinel lymph node identification in patients with breast cancer]. 
Sentinel lymph node biopsy is nowadays an accepted method of staging breast cancer patients.  In case of an injection of radioactive colloid, preoperative lymphoscintigraphy is recommended to establish a lymphatic mapping and to predict the number of sentinel lymph nodes identified during surgery.  Preoperative lymphoscintigraphy does not decrease the false-negative rate.  However, positive preoperative lymphoscintigraphy significantly improves the identification rate of intraoperative sentinel nodes comparing with negative preoperative lymphoscintigraphy.  Detecting extra-axillary sentinel lymph nodes, because of its minimal therapeutic consequences, does not appear to be an indication for preoperative lymphoscintigraphy.  Given logistics and cost required, preoperative lymphoscintigraphy should be only performed for patients with a high risk of intraoperative failed localization.  In case of negative preoperative lymphoscintigraphy, sentinel lymph node biopsy must be tried because sentinel nodes are still identified in the majority of these patients.  Another possibility, with important cost and logistic, should consist in performing a later lymphoscintigraphy on the day after radioactive injection to ameliorate sentinel lymph nodes identification.