Evaluation of early versus delayed lymphoscintigraphic imaging in detecting internal mammary sentinel lymph nodes in breast cancer: a multicenter study to establish an optimal lymphatic mapping protocol.

OBJECTIVE

Metastases in the internal mammary lymph nodes have an important prognostic value in breast cancer. Lymphatic mapping and sentinel node biopsy of internal mammary nodes improves staging and permits specific therapeutic strategies, thereby possibly improving final outcome. Therefore, optimal lymphoscintigraphic results are needed. Visualization of internal mammary lymph drainage, however, is influenced by several factors. We evaluated the effect of different time intervals between radioactive tracer injection and lymphoscintigraphy on visualization of internal mammary sentinel lymph nodes.

METHODS

From February 1997 to August 2001 a total of 682 eligible breast cancer patients underwent sentinel lymph node mapping. The technique involved the injection of 370 MBq (10 mCi) (99m)Tc-nanocolloid peritumorally. In 470 patients (group A) the time interval between injection of the radiocolloid and lymphoscintigraphy was 16 h, compared to 2.5 h in 212 patients (group B).

RESULTS

Patient characteristics showed no statistically significant difference between both groups for age and location of the tumour. Axillary hotspots were visualized in 97% in group A and 96% in group B. Lymphoscintigraphy showed internal mammary hotspots in 21% in group A, compared to 27% in group B. The mean number of internal mammary hotspots per patient was 1.9 in group A and 1.8 in group B.

CONCLUSIONS

We found no significant differences between early and delayed lymphoscintigraphic imaging in visualizing internal mammary sentinel lymph nodes.