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[Validation study of the sentinel lymph node (SLN) method in invasive breast carcinoma. Personal data and review of the literature].

BACKGROUND
Axillary lymph node dissection (ALND) is an integral part in the therapy of breast cancer. Axillary lymph node involvement and tumour size are the most important prognostic factors. Restriction of ALND to level I and II (Berg) reduced high morbidity. The increasing proportion of patients with early breast cancer and negative axillary nodes led to a more selective method to avoid unnecessary ALND. The sentinel lymph node (SLN)--the first draining lymph node of a tumour--represents the status of the axilla. A negative SLN prevents from further completion ALND.


PATIENTS AND METHODS
From 9/97 to 1/99 44 patients with invasive breast cancer underwent a prospective trial of lymphatic mapping with isosulfanblue and/or lymphoscintigraphy with 99m technetium-labelled human colloid. During the operation a hand-held gamma probe was used for detection. The SLN was removed selectively and examined by routine histopathology (H&E) and immunohistochemistry (IHC). ALND of level I and II was performed in all patients for correlation.


RESULTS
The SLN were identified in 41 of 44 patients (93%). 2.4 SLN per patient were harvested, overall 17.6 axillary lymph nodes. Of the 41 patients, 21 patients had positive, 20 patients negative SLN. In the 20 patients with negative SLN only one patient (5%) had metastatic disease on complete dissection (negative predictive value of 95%). In 17 patients with positive axillary lymph nodes 16 were found to have positive SLN, only one SLN was negative (false negative rate of 5.9%). In two of 41 patients micrometastases were detected by IHC. Lymphoscintigraphy revealed drainage to the axilla and internal mammary nodes in two of 28 cases (7%).


SUMMARY
Our validation study proves the reproducibility and reliability of the SLN procedure. A multidisciplinary approach is indispensable. The SLN procedure has the potency for becoming the selection criterion whether to perform an ALND or not. Multiple sections and IHC staining improve the detection rate of metastatic disease. Ongoing long time investigations will determine the impact on overall survival. Our own data are discussed in an extended review of the literature.