Page 42 - Sentinel lymph node biopsy in oral cavity cancer - Inne J. den Toom

Chapter 2 rates have a longer follow-up allowing occult metastases to become clinically manifest. The regional recurrence rate in SLNB positive patients was 3/26 (12%). In 2 patients recurrence was found in operated levels, one patient with a well lateralized tumour developed regional metastasis contralaterally, so this metastasis would also have been missed by conventional ipsilateral END. This recurrence rate in SLNB positive patients is relatively high compared to Pezier et al. and Gurney et al. who reported rates of 6%.14,28 However, a systematic review of 109 papers found regional recurrence rates of 13% in surgically treated early stage oral cancer.29 Moreover, a recently published two- center review of 164 patients with pT1-T2 squamous cell carcinoma of the tongue and pathologically staged N0 by END reported a regional (with or without local) recurrence rate of 18%.30 In the cohort of patients with SPECT-CT as imaging technique (57/88 (65%)) none of the patients with a negative SLNB developed a regional recurrence in the follow- up, however the follow-up in this cohort is only 10 months. In contrast to the cohort without SPECT-CT, 2 patients with a negative SLNB developed regional metastasis, resulting in a false negative rate of 2/31 (7%). It should be mentioned that the follow-up in this cohort is 40 months. Because of the small number of patients and the difference in follow-up between the groups, evaluation of SPECT-CT in the present study is complicated and further research is mandatory. As found in other studies, preoperative lymphoscintigraphy identified SLNs with high accuracy (98%) and SLNs were also found outside the expected drainage pathways, which is recognized as one of the benefits of SLNB.21,31-33 Another benefit of SLNB is reducing the number of dissected lymph nodes for histopathological evaluation, compared to END. By selection of the nodes which are most representative for the nodal neck status thorough evaluation by SSS and IHC is possible, this in contrast to routine histopathological evaluation of a ND specimen, in which the large number of removed lymph nodes would make thorough evaluation too laborious. SSS and IHC are suitable for the detection of micrometastasis and ITC which probably would have been missed using routine histopathological evaluation. In the SLNB positive patients, 62% (16/26) was staged positive due to the presence of a micrometastasis or ITC. This high prevalence confirms the importance of these meticulous histopathological technique. In the 25 neck dissections, only in 5/9 (56%) patients with macrometastasis, additional positive lymph nodes were found in the ND specimen (Table 2). This is partly in contrast with Broglie et al., who found in 2 of 10 (20%) patients with ITCs and in 4 of 32 (13%) patients with micro- or macrometastases additional positive lymph 40