Pattern of lymphatic drainage to the sentinel lymph node in breast cancer patients

We performed a pilot study on 30 consecutive patients undergoing sentinel node (sN) biopsy by radioguided surgery and vital blue dye mapping to determine whether there is a single sN for each breast independent of tumor site or an sN specifically related to the site of the breast neoplasm.

There were 6 groups of 5 patients; each patient had a subdermal injection of radiotracer on the tumor site plus a second injection of radiotracer that was changed in every subset of patients to test whether modifying the site or the route of injection could have impaired the proper detection of the sN.

"False" sN were detected only in patients who had a second injection of radiotracer away from the tumor site; this occurred in 2 of 5 patients (40%) in group I, in 3 of 5 patients (60%) in group II, in all patients in group III, and in 3 of 5 patients (60%) in group IV. The different route of injection (peritumoral or subdermal) always on the tumor site that was tested in groups V and VI did not impair the proper detection of the sN.

Our findings support the hypothesis of a precise topographic correspondence between the primary tumor and its specific sN more than the existence of a first sN in the axillary basin, which indiscriminately drains all quadrants of the breast, like "a neck of a bottle." This should be considered for the proper selection of the injection site of either vital blue dye or radiopharmaceuticals.