Optimal sentinel node examination and a new strategy for axillary control in breast cancer.

The sentinel lymph nodes (SLNs) have been reported to reflect the other nodal status in breast cancer, and it is thought that axillary dissection can be avoided in SLN-negative patients, whereas an additional axillary dissection must be performed for SLN-positive patients. To avoid any unnecessary dissection, non-SLN-negative patients should be distinguished among SLN-positive patients. In this study, an optimal histological examination of SLNs was investigated for a precise indication of additional axillary clearance. A modified radical mastectomy with an axillary dissection was performed for 61 patients. Technetium-labeled tin colloids were used to identify the SLNs. In all lymph nodes that were diagnosed as negative at one section by hematoxylin and eosin (H&E) examination, another additional slice was produced for each lymph node. We evaluated how minute areas of cancer in the SLNs can indicate the non-SLNs to be negative. Among 1,092 lymph nodes previously diagnosed by H&E examination as negative at one section, 3 nodes were revealed to be positive in 46 SLNs (6.52%), whereas in additional slices, only 3 nodes out of 1,046 non-SLNs were positive (0.29%). The mean ratio of the cancer cell area to the whole area of SLN on the slice was 15.6% (10-18%) in 12 non-SLN-negative patients and 45.6% (30-83%) in 16 non-SLN-positive patients. It is possible that additional axillary clearance is not needed for patients with a cancer area of less than approximately 20% in the SLN slice, based on an H&E staining evaluation of two slices. SLNs identified with radiolabeled tin colloids could reflect the other nodal status in breast cancer. There is a possibility that additional axillary clearance is not needed for patients with a cancer area of less than approximately 20% in the SLN slice.