Can Sentinel Lymph Node Biopsy Predict Various Levels of Echelon Nodes in Oral Cancers?

THIEME Original Research Can Sentinel Lymph Node Biopsy Predict Various Levels of Echelon Nodes in Oral Cancers? Ramya Rathod1 Amanjit Bal3 Jaimanti Bakshi1 Naresh Kumar Panda1 1 Department of Otolaryngology, Head & Neck Surgery, Post- Graduate Institute of Medical Education and Research, Chandigarh, Chandigarh, India 2 Department of Nuclear Medicine, Post-Graduate Institute of Medical Education and Research, Chandigarh, Chandigarh, India 3 Department of Pathology, Post-Graduate Institute of Medical Education and Research, Chandigarh, Chandigarh, India Roshan Verma1 Anish Bhattacharya2 Address for correspondence Ramya Rathod, MS, Department of Otolaryngology, Head and Neck surgery, Post graduate institute of medical education and research, Sector-12, Chandigarh, India (e-mail: ). Int Arch Otorhinolaryngol 2020;24(2):e131–e137. Abstract Keywords ► sentinel node ► oral cancer ► neck dissection ► lymphoscintigraphy ► technetium received June 6, 2019 accepted June 20, 2019 published online November 4, 2019 Introduction The efficacy of sentinel node biopsy in early stage oral cancer is well established. Its evolving role can be reinforced by further studies. Objective Analyzing the predictability of the levels of echelon nodes for various oral cavity tumor subsites on sentinel node biopsy. Methods A prospective study of 20 patients with stage I/II oral squamous cell carcinoma who underwent sentinel node biopsy-guided neck dissection between January 2017 and 2018 at our institute. The procedure included radiotracer injection, imaging (lymphoscintigraphy, single photon emission computed tomography-computed tomography), and gamma probe application. Sentinel node detection on imaging and gamma probe were compared. Results Out of 20 patients, 13 (65%) had carcinoma of the tongue, 6 (30%) had buccal mucosa carcinoma, and 1 (5%) had retromolar trigone carcinoma. The mean age of the patients was 52.3 years. A total of 13 (65%) patients were male, and 7 (35%) were female. The sentinel node identification rates with imaging and gamma probe were of 70% and 100% respectively. In tongue and retromolar trigone primaries, the most common first-echelon nodes in both modalities were levels IIA and IB respectively. For buccal mucosa primaries, first-echelon nodes were detected only with the gamma probe, which was level IB. On imaging, second-echelon nodes were detected only for tongue primaries, and had equivalent incidence of levels II, III, and IV. On the gamma probe, level IIA, followed by III, and IV for the tongue, and level IIA were the most common second-echelon nodes for the buccal mucosa. Third-echelon nodes were detected only with the gamma probe for tongue carcinoma at level IV. Conclusion The combined use of imaging and gamma probe provides the best results, with high identification rate and predictability of echelon levels. DOI https://doi.org/ 10.1055/s-0039-1695762. ISSN 1809-9777. Copyright © 2020 by Thieme Revinter Publicações Ltda, Rio de Janeiro, Brazil 131 132 Can Sentinel Lymph Node Biopsy Predict Various Levels of Echelon Nodes in Oral Cancers? Rathod et al. Introduction Cervical lymph node (LN) metastasis is the single most important prognostic factor in squamous cell carcinoma of the head and neck, which can decrease the 5-year survival rates from 80% to < 50%. None of the currently available imaging methods reliably depicts small tumor deposits in non-enlarged LNs or differentiates reactively enlarged LNs from metastatic adenopathy. Therefore, necks with oral cancer in stages I and II are managed when the risk of micrometastasis is > 30%, in which case either radiotherapy or elective neck dissection (END) are performed.1 There is a paradigm shift from extensive to selective neck dissection (SND) for oral cavity cancers. But the rate of skip metastases to level IV is
10% for tongue primaries. Thus, the concept of sentinel LN biopsy (SLNB) came to be. It mimics the physiological migration of cancer cells from the tumor to the LNs, with migration of a known detectable tracer.2 Technetium 99 m (Tc 99 m) sulfur colloid is the most commonly used radiotracer agent, with a physical half-life of 6 hours.3 Depending on the size of the particle, the radiotracer can move down the lymphatics from the first-echelon node to the second and third-echelon nodes. Smaller particles drain quickly from the sentinel node, and tend to accumulate in non-sentinel nodes, whereas larger particles drain slowly and are retained within the sentinel nodes.4 The gamma camera interacts with the gamma rays emitted from the radionuclide injection site, and gives total radiotracer uptake and its spatial distribution within the tissue.5 Single photon emission computed tomography-computed tomography (SPECT-CT) gives better definition to the images, with the location of the LNs relative to anatomical landmarks, and also reduces the obscuring of nodes by activity of an injection site that is near the tumor.6 In the present study, our objective was to determine the ability of this modality to predict first-, second-, and thirdechelon node levels for various tumor subsites of the oral cavity. Methods The study was conducted at the Department of Otolaryngology and Head & Neck Surgery in collaboration with the Department of Nuclear Medicine and the Department of Pathology at our institute. This was a prospective study with a total of 20 diagnosed patients of early-stage oral cancers. Prior approval was obtained from the ethics committee of the institution, with reference no. NK/4238/MS/ 2224–25. The treatment plan was discussed in detail with the patient and their attendants, and informed and written consent was sought before proceeding with the study. The minimum follow-up period planned was of 6 months, and the maximum follow-up period was variable. All diagnosed cases of stages I and II oral cavity cancers were included, and patients with T3 or T4 diseases, irrespective of nodal status, with node-positive neck, with malignancy of multiple subsites of the oral cavity, any other coexisting malignancies, previous history of surgical treatment of the neck, radiotherapy or chemotherapy, and International Archives of Otorhinolaryngology Vol. 24 No. 2/2020 Fig. 1 Radiotracer being injected in the anterior quadrant of the primary tumor, which is located on the middle third of the left lateral border of the tongue. patients unfit for surgery due to associated comorbidities were excluded from the study. Technique: sentinel lymph node (SLN) biopsy-guided neck dissection þ wide local excision (WLE) of the primary tumor. A 4-quadrant peritumoral, submucosal injection of filtered Tc 99 m sulfur colloid radiotracer in a dose of 0.1 millicurie in each quadrant, and particle size of 220 nm, was administered an hour prior to taking up the patient for surgery (►Fig. 1). The radiotracer was procured from the Board of Radiation and Isotope Technology (BRIT), a unit of the Department of Atomic Energy of the g (...truncated)