Impact of patient- and disease-specific factors on SLNB in breast cancer patients. Are current guidelines justified?

BACKGROUND: The evidence on which to base guidelines for sentinel lymph node biopsy (SLNB) in breast cancer is still limited. In order to facilitate the further implementation of renewed guidelines, we evaluated patient- and disease-specific factors for their impact on the results of SLNB.
MATERIALS AND METHODS: Prospective data acquisition from patients undergoing surgery for primary invasive breast cancer was performed. All patients underwent SLNB using the radiocolloid or the combined technique. The association of patient- and disease-specific factors to detection rate and false-negative rate was calculated using univariate and multivariate analyses (P < 0.05 considered as significant). Calculation of the false-negative rate was based on patients who underwent a backup axillary dissection.
RESULTS: Among 455 consecutively enrolled patients, a significant inverse association to the detection rate was found for extracapsular extension of non-SLN metastases, body mass index (BMI), number of involved lymph nodes, pT category, tumor size, and age. A significant association to the false-negative rate to identify macrometastases was found for pT category, tumor size, and grading. Other factors, such as prior surgery, multicentric tumor growth, or vascular invasion, showed no influence. A cut-point analysis revealed that a tumor size of 2 cm separated the collective of patients with the highest significance in regard to the false-negative rate (9% vs. 25%).
CONCLUSION: Our results indicate that SLNB can be safely used in elderly and obese patients with multicentric tumors and those having undergone prior surgery for benign breast disease. However, the method should be applied with caution in patients with tumors larger than 2 cm.