Page 172 - Sentinel lymph node biopsy in oral cavity cancer - Inne J. den Toom

Summary, general discussion and future perspectives Assuming that lymphatic drainage is expected normally in levels I-III for oral cavity cancer, in 30% (13/43) of the patients unexpected drainage was found. Besides the described study of Flach et al., no other studies are published for SLNB in early stage oral cavity cancer with a previously treated neck.48 Correlating to patients with an untreated neck, unexpected drainage patterns were reported in 16% of patients in a large multicenter trial.50 However, in a variety of other tumour types SLNB has been described in recurrent or second primary tumours. In recurrent breast cancer lower identification rates were observed and aberrant lymphatic drainage were seen in up to 40%.51,52 Extra-axillary lymphatic drainage and drainage to the contralateral axilla was significantly more observed in patients previously treated with axillary lymph node dissection ALND compared to prior SLNB. Both studies concluded that repeat SLNB is feasible and should replace routine ALND as standard axillary restaging procedure in recurrent disease. Similarly in recurrent vulvar cancer and melanoma unpredicted drainage patterns were found compared to previously untreated patients.53,54 These findings strengthen the value of SLNB in assessing the individual lymphatic drainage pattern. Identifying individual lymphatic drainage patterns was exactly the idea of Cabañas when performing SLNB in the first patients in 1977.55 In the first decades SLNB identification was done with planar static and dynamic lymphoscintigraphy only.56 Visualization of SLNs could also be performed by single photon emission computed tomography with computed tomography (SPECT-CT). SPECT-CT was introduced in 2003 for SLNB in oral cancer.57 As described in a review SPECT-CT provides useful information in localization of SLNs and showed additional SLNs compared to planar dynamic and static lymphoscintigraphy.58 To determine the added value of SPECT-CT we analyzed 66 patients with early stage oral cavity cancer (chapter 7). According to the definition of Morton et al. a clear visible and rapidly appearing lymph node was considered to be a SLN.59 In one patient no SLN could be identified on both imaging modalities (identification rate 98%). In 22% of the patients (14/65), 15 additional SLNs could be identified due to SPECT-CT. In two of these additional SLNs metastasis were found, resulting in an upstaging rate due to SPECT-CT of 3% (2/65). A positive SLNB was found in 10 patients and in of two of these patients (20%) the positive SLN was identified due to the addition of SPECT-CT. We found that five SPECT-CT scans are needed to identify one additional SLN. For identification of one positive SLN this number is 34. In contrast to add SLNs, SPECT-CT also diminished in five patients the number of SLNs based on planar lymphoscintigraphy (e.g. injection spot rather than SLN in four patients). In comparison with our results both lower, comparable and higher 170