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 i ntradermally) used in search for the sentinel node(s) in patients with brea st cancer. Methods: Ninety-nine patients were peri-tumourally injected with 2 ml 60 MB q 99m-Tc-Nanocoll and underwent lymphoscintigraphy about 18 h later to dete ct 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-areo larly in the quadrant of the tumour. Dynamic and static images were taken t o visualize the (intradermal) lymphatic spread and accumulations. Special a ttention was paid to match or mismatch of hot spots visualized by both tech niques. 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 remaini ng 55 patients, in 52 there was complete concordance of the axillary hot sp ots. However, there was a so-called 'regional mismatch' in nine of these pa tients concerning the internal mammary nodes. In the three remaining patien ts 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 inject ion 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 mamm ary nodes visualized after peri-tumoural injection are not visualized by th e intradermal technique. Para-areolar intradermal injection of Nanocoll for detection of sentinel nodes in patients with breast cancer needs further e valuation, because it seems to be a more practical procedure.