AIM of this study was to determine whether the sentinel lymph nodes (SLNs) can be accurately identified in breast cancer patients with intradermal injection of the radiotracer above the primary tumour in comparison to peritumoural injection.
Methods: In 45 women with breast cancer we performed lymphoscintigraphy on two separate days. We injected Tc-99m nanocolloid on the first day peritumourally, and on a separate day intradermally. The results of both investigations using different injection sites were compared in order to determine the number and location of SLNs.
Results: The SLN identification rate using peritumoural injection was 71% (32 of 45 patients) and 96% (43 out of 45 patients) using intradermal injection. In 62% (28 of 45 patients) the number and location of the SLNs were identical. In 97% (31 of 32 patients) in whom a SLN was detected using peritumoural injection, the same SLNs reappeared with intradermal injection. There were no false negative findings with the peritumoural administration of tracer whereas the intradermal administration approach resulted in a false negative rate of 13%.
Conclusion: In women with breast cancer the reproducibility of lymphoscintigraphy using peritumoural and intradermal injection sites was 62%. The intradermal injection modality enables the detection of a SLN in patients where the peritumoural injection failed but it has the disadvantage of a higher false negative rate in comparison to the peritumoural injection technique.