Multifocality and sentinel node biopsy in breast cancer

Sentinel node biopsy allows us to identify node negative patients who do not require axillary lymph node dissection (ALND) and can be spared the morbidity associated with ALND.1. and 2. It has been suggested that sentinel node biopsy is not suitable for multicentric lesions, inflammatory and locally advanced carcinomas, in those with previous axillary surgery or surgery to the breast such as reduction mammoplasty, previous radiation therapy or chemotherapy, and suspicious axillary lymph nodes.3 However, little data exists to support these contraindications and recent studies are clarifying the role of sentinel node biopsy in several settings. The concept of sentinel node biopsy has been validated for unifocal breast cancer,3. and 4. whereas multifocal or multicentric breast cancer is generally thought to be a contraindication for sentinel node biopsy. Most of the studies available in the literature have excluded patients who had a multifocal or multicentric breast mass on the assumption that tumours located in different breast quadrants drain to different lymph node sites and not to the same sentinel node. Therefore, sentinel lymph node (SLN) mapping procedure based on only one invasive tumour may miss the SLNs associated with the second invasive tumour. Sentinel node biopsy in patients with multifocal breast cancer has been associated with increased false negative rates in literature. The accuracy of SLN biopsy in multifocal breast cancer was first questioned by Veronesi et al.3 in 1997. Their study showed a false-negative rate of 2.5%, but two of the four patients with false-negative results had multifocal disease. They concluded that the risk of false-negative results is low, and can be further reduced if multicentric/multifocal tumours are excluded. However, the evidence is based on four patients and reflects the early experience of SLN mapping and biopsy at the reporting institution. The lymphatic drainage of the breast is poorly understood. Results of the various SLN biopsy techniques provide valuable information on the lymphatic drainage of the breast. Klimberg and colleagues5 have reported equal identification rates of the sentinel node for the subareolar injection site and the peritumoural injection site. The SLN was successfully identified in 89.9% using the blue dye and 94.2% using the technetium radiocolloid. The concordance rate between the two techniques was 89.9%. Borgstein et al.6 demonstrated a 100% concordance in localizing the SLN utilizing an intradermal injection of blue dye and an intraparenchymal injection of radioisotope; the concordance rate in the study by Linehan et al.7 was 95%. As the different sentinel node biopsy techniques accurately lead to identification of the same SLN, these studies support the hypothesis that the drainage of the breast is fairly constant in most patients. The breast tumours drain through a few common afferent lymphatic channels to a common axillary SLN, regardless of tumour location. Therefore, lymphatic mapping in patients with multifocal cancers may also be possible, allowing these patients to be spared the morbidity of ALND. In the ALMANAC trial validation phase,8 75 of the 842 patients had multifocal or multicentric lesions on histopathologic examination. Sentinel node was successfully identified in 95%(71/75) patients with multifocal tumours. Sentinel node biopsy with the peritumoural injection technique accurately predicted lymph node status in 95.8%(68/71) patients with multifocal brest cancer. The false negative rate (8.8%) and the negative predictive value (92.5%) was similar to that in the unifocal group. Sentinel node biopsy may thus prove to be a reliable alternative to complete axillary dissection in patients with multifocal breast cancer with clinically negative lymph nodes