Objective: To investigate the feasibility of internal mammary sentinel lymph node biopsy as a method to refine and thereby improve nodal staging in breast cancer.
Summary background data: The internal mammary lymph node status is a major prognostic factor in breast cancer. If positive, prognosis is less favorable. However, staging this regional nodal basin is not performed routinely, thus discarding additional staging information.
Methods: In a consecutive series of 256 patients with primary breast cancer, sentinel node biopsy was performed based on lymphoscintigraphy, intraoperative gamma probe detection, and blue dye mapping using 10 mCi (370 MBq) (99m)Tc-nanocolloid injected peritumorally and 0.5 to 1.0 mL Patent Blue V injected intradermally. During surgery, whenever possible, both axillary and internal mammary sentinel nodes were sampled.
Results: Lymphoscintigraphy showed axillary sentinel nodes in 95% (243/256) and additional internal mammary sentinel nodes in 25.3% (65/256). The overall success rate of axillary sentinel node biopsy was 97% (249/256). Sampling the internal mammary basin, based on the results of lymphoscintigraphy, was successful in 63% (41/65). In three patients a small pleural lesion resulted from staging this basin. This technique revealed internal mammary metastases in 26.8% (11/41). In 7.3% (3/41), internal mammary nodes showed metastatic involvement without accompanying axillary metastases.
Conclusions: Internal mammary sentinel node biopsy is feasible without serious additional complications. It improves nodal staging in breast cancer by identifying higher-risk subgroups with internal mammary nodal metastases, which might benefit from altered adjuvant treatment regimens.