Sentinel node biopsy in primary breast cancer: radioactive detection and metastatic disease

To examine the relationship between the intensity of the radioactive counts and the presence of tumor metastasis in sentinel lymph nodes (SLNs) in order to correctly identify the number of SLNs to be removed.

Five hundred three breast cancer patients with successful radioisotope localization of SLNs using the combined blue dye and radioisotope method were analyzed. SLN biopsy was continued until all the blue-stained and radioactive nodes were removed.

The mean number of harvested SLNs was 1.7+/-0.9, and the number of radioactive SLNs among the harvested nodes was 1.6+/-0.8. SLN metastasis was found in 123 of the 503 cases. The metastasis was detected in the SLN with the highest radioactive count (the hottest SLN) in 94 of the 123 cases with positive SLNs. The positive rate in the hottest SLN was 89% in 61 cases with a single radioactive SLN, and 65% in 62 cases with multiple radioactive SLNs. Of the 29 cases with positivity in other than the hottest SLNs, the metastasis was detected in the second hottest SLN in 16 cases, in the third hottest SLN in one case, in a mixture of negative radioactive SLNs and blue-dye-stained in four cases, and in the negative SLNs and positive non-SLNs (false-negative) in eight cases. Of 123 node-positive cases, 111 cases had metastasis that was detected within the first three hottest SLNs.

These data suggest that lymph node metastasis may not always be detected in the hottest SLN. Thus, in practice, all radioactive and/or blue-dye-stained nodes should be removed for further examination.