Results of a standardized protocol for sentinel node imaging in breast cancer with Tc-99m labeled nanocolloidal albumin.

Aim: Of this study was to evaluate the results of a standardized protocol for sentinel node (SN) detection in breast cancer using Tc-99m labeled nanocolloidal albumin and a combined intra- and subdermal injection technique.

Methods: One hundred and fifty-five women with proven breast cancer (disease stages Tis-T2) were included. Four injections of 10 to 15 MBq of Tc-99m nanocolloid in 0.1 ml physiologic saline were administered intra- and subdermally at the 3, 6, 9 and 12 o'clock positions in the skin overlying the tumor. Planar scintigraphic images in lateral and anterior projections were obtained once between 2.5 and 18 hours after tracer administration. Guided by a gamma probe, all radioactive lymph nodes in the axilla were resected, then complete dissection followed.

Results: In 151 of the 155 women (97.4%), nodal tracer uptake (range 1-7 foci, average 2.2) was scintigraphically revealed. In one of these cases, drainage was only to the internal mammary lymphatic chain. Three of the 4 women with detection failure presented with histologically proven tumor infiltration of the lymphatics and axillary involvement. In 49 of the patients with visualized axillary lymph nodes (32.7%), at least one SN was metastatic. In 21 cases, this SN was the only positive node. The remaining 101 patients with negative SN included 4 cases with axillary involvement. The sensitivity of the SN with respect to the histological status of the entire axilla was thus 92.5%, the negative predictive value was 96.0%. The overall accuracy of the method was 97.3%. There was a significant difference between the number of totally detected radioactive nodes in the groups with and without nodal metastases (3.49 vs. 2.57, p < 0.01).

Conclusion: The described protocol represents an easy reproducible and reliable method for SN detection in breast cancer that additionally allows flexible timing of surgery. Further, we found evidence that the number of scintigraphically visualized nodes also reflects the histological status of the axilla.