In search of the true sentinel node by different injection techniques in breast cancer patients

Aims: To evaluate two different injection techniques (peri-tumourally and intradermally) used in search for the sentinel node(s) in patients with breast cancer. Methods: Ninety-nine patients were peri-tumourally injected with 2 ml 60 MBq 99m-Tc-Nanocoll and underwent lymphoscintigraphy about 18 h later to detect focal accumulations. Next, they were injected intradermally with 0.2 mi 15 MBq 99m-Tc-Nanocoll either in the skin overlying the tumour or para-areolarly in the quadrant of the tumour. Dynamic and static images were taken to visualize the (intradermal) lymphatic spread and accumulations. Special attention was paid to match or mismatch of hot spots visualized by both techniques. Results: Ninety-four patients had positive peri-tumoural and/or intradermal accumulations which could be compared. In 30 patients only peri-tumoural, and in nine only intradermal, identification was successful. Of the remaining 55 patients, in 52 there was complete concordance of the axillary hot spots. However, there was a so-called 'regional mismatch' in nine of these patients concerning the internal mammary nodes. In the three remaining patients there was a sequential mismatch in the axilla: before draining lymph to the peri-tumourally visualized hot spot, an interposed node was encountered first after the intradermal injection technique. Conclusions: Intradermal injection is complementary to peri-tumoural injection for visualization of focal accumulations in patients with breast cancer. The two different injection techniques have a small number of sequential mismatches for hot spots in the axillary region. This means that it may be unclear which separate route leads to the true sentinel node. Internal mammary nodes visualized after peri-tumoural injection are not visualized by the intradermal technique. Para-areolar intradermal injection of Nanocoll for detection of sentinel nodes in patients with breast cancer needs further evaluation, because it seems to be a more practical procedure.