Sentinel lymph node biopsy in patients with multifocal breast cancer.

Background: Multifocal or multicentric breast cancer has been suggested as a contraindication for sentinel node biopsy (SNB). However, recent studies have demonstrated that all quadrants of the breast drain through common afferent channels to a common axillary sentinel node. This should mean that the presence of multifocal tumour should not affect the lymphatic drainage. The purpose of this study was to evaluate the feasibility and accuracy of SNB in patients with multifocal breast cancer using a peritumoural injection technique for sentinel lymph node (SN) mapping.

Methods: In the ALMANAC multicentre trial validation phase, we took SNB samples from 842 patients with node negative, invasive breast cancer with use of a blue dye and radiolabelled colloid mapping technique at the peritumoural injection site. All patients underwent standard axillary treatment after SNB. Seventy-five of the 842 patients had multifocal lesions on final histopathologic examination. The following analysis is focused on patients with multifocal lesions.

Results: A mean number of 2.4 SNs were identified in 71 of 75 patients (identification rate: 94.7%). Thirty-one patients had a positive SN, 40 a negative SN. Standard axillary treatment confirmed the SN to be negative in 37 of 40 patients, whereas three patients revealed positive non-sentinel lymph nodes (false-negative rate: 8.8%). Overall SN biopsy accurately predicted axillary lymph node status in 68 of 71 patients (95.8%).

Conclusion: SNB accurately staged the axilla in multifocal breast cancer and may become an alternative to complete axillary lymph node dissection in node negative patients with multifocal breast cancer.