Sentinel lymph node drainage in multicentric breast cancers
Axillary lymph node status is the most important prognostic marker in patients with breast cancer; the presence of axillary metastases impacts prognosis as well as subsequent systemic therapy. Axillary lymph node dissection (ALND) is associated with significant morbidity and psychological distress; the introduction of sentinel lymph node (SLN) biopsy with lymphatic mapping affords the ability to identify those patients most likely to benefit from ALND, sparing node-negative patients. The lymphatic drainage of the breast is poorly understood, and the situation is further complicated by the lack of standardization of the SLN biopsy technique among institutions. Multicentricity has generally been considered to be a contraindication to SLN biopsy due to concerns about potential inaccuracies. Here we report five cases of patients with multicentric breast cancers (two tumors in two distinct quadrants). In each case, injection of one site with technetium-labeled sulfur colloid and the second site with isosulfan blue dye resulted in successful identification of at least one node that was both hot and blue within the axilla. These observations suggest that the lymphatic drainage of the entire breast coincides with drainage of the tumor bed, regardless of the quadrant. However, further studies are needed to validate the accuracy of SLN biopsy in multicentric breast cancers.