[Preoperative lymphoscintigraphy to identify the sentinel lymph node in breast cancer].

Introduction: The preoperative lymphoscintigraphy to the Sentinel Node Biopsy (SNB) can reproduce the lymphatic drainage of the tumour in breast cancer.

Objectives: To establish the pattern of lymphatic drainage of the mammary tumors by means of isotopic lymphoscintigraphy and determine the factors that could influence the negativity of the scintigraphy.

Methods: 121 patients with breast cancer who were going to undergo mammary surgery were studied with SNB. One day before the operation, 37 MBq 99mTc-colloidal sulphide colloid in a volume of 2 ml was injected in peritumoral tissue. Mammary lymphoscintigraphies were performed at 30 minutes and 18 hours P.I., in ANT and OA projections of the corresponding chest. After, the clinical-biological parameters and their influence on the result of the lymphoscintigraphy were analyzed.

Results: The scintigraphy were positive in 85 % of the patients. The axillary chain was observed in 97 % and the internal mammary chain in 11 %. The factors associated to the absence of visualization of the sentinel node were: older than 50 years (94 %), menopause (89 %), tumoral size > or = 2 cm (67 %), axillary metastases (67 %), the overexpression of C-erbB-2 oncoprotein (44 %) and proliferative activity > 10 % (67 %).

Conclusions: The peritumoral injection of the radiocolloid establishes the lymphatic drainage pattern in the patients with breast cancer. Its absence of visualization can be associated to circumstances like: age > or = 50 years, menopause, tumoral size > or = 2 cm, axillary metastases, tumoral overexpression of the C-erbB-2 oncoprotein and high proliferative activity of the mammary tumor.