Challenges and outcomes in establishing a sentinel lymph node biopsy service for oral squamous cell carcinoma in a regional district specialist hospital

Evaluation of micrometastasis and isolated tumor cells in node-negative early-stage oral tongue squamous cell carcinoma: a cross-sectional study in tertiary-level hospitals in eastern India

OBJECTIVE

The present study aimed to investigate the incidence of micrometastasis (MMs) and isolated tumor cells (ITCs) in node-negative early-stage oral tongue squamous cell carcinoma (T1-T2 N0). The secondary objective was to correlate the incidence with the clinicopathologic parameters of age, sex, depth of invasion, pattern of invasion, host lymphocytic response, and size and grade of primary tumor.

STUDY DESIGN

Micrometastasis and ITCs in cervical nodes of 30 patients with early-stage oral tongue squamous cell carcinoma were detected and compared using 3 methods: routine hematoxylin and eosin staining, serial-sectioning at intervals of 150 microns employing hematoxylin and eosin, and serial sectioning pan-cytokeratin immunostaining. Associations with clinicopathological variables were analyzed.

RESULTS

Metastatic tumor cells were detected in the cervical nodes of 2 patients using serial sectioning and immunohistochemistry, resulting in upstaging of 6.6% of all cases. Level I and II lymph nodes were primarily involved.

CONCLUSIONS

Early-stage oral tongue squamous cell carcinoma has a significant potential for MMs that frequently go undetected in routine histopathologic examination. However, laborious and technique-sensitive, serial sectioning in combination with pan-cytokeratin staining (AE1/AE3) may aid in detecting MMs and ITCs in patients with early-stage OTSCC.

Surgical Extent for Oral Cancer: Emphasis on a Cut-Off Value for the Resection Margin Status: A Narrative Literature Review

The optimal cut-off point of the resection margin was recently debated in oral cancer. To evaluate the current evidence of the dynamic criteria of the resection margin, a review of the available literature was performed. Studies were sourced from PubMed and EMBASE by searching for the keywords "mouth neoplasm", "oral cancer", "oral cavity cancer", "oral squamous cell carcinoma", "tongue cancer", "margins of excision", "surgical margin" and "resection margin". We found approximately 998 articles on PubMed and 2227 articles on EMBASE. A total of 3225 articles was identified, and 2763 of those were left after removing the duplicates. By applying advanced filters about the relevance of the subjects, these were narrowed down to 111 articles. After the final exclusion, 42 full-text articles were reviewed. The universal cut-off criteria of 5 mm used for determining the resection margin status has been debated due to recent studies evaluating the impact of different margin criteria on patient prognosis. Of note, the degree of the microscopic extension from the gross tumor border correlates with tumor dimensions. Therefore, a relatively narrow safety margin can be justified in early-stage oral cancer without the additional risk of recurrence, while a wide safety margin might be required for advanced-stage oral cancer. This review suggests a surgical strategy to adjust the criteria for risk grouping and adjuvant treatments, according to individual tumor dimensions or characteristics. In the future, it might be possible to establish individual tumor-specific surgical margins and risk stratification during or after surgery. However, the results should be interpreted with caution because there is no strong evidence (e.g., prospective randomized controlled studies) yet to support the conclusions. Our study is meaningful in suggesting future research directions and discussions.

CT Lymphography Using Lipiodol® for Sentinel Lymph Node Biopsy in Early-Stage Oral Cancer

This study evaluated sentinel lymph node (SLN) identification with CT lymphography (CTL) following peritumoral administration of Lipiodol^® relative to conventional ^99mTc-nanocolloid lymphoscintigraphy (including SPECT/CT) in 10 early-stage oral cancer patients undergoing SLN biopsy. Patients first underwent early dynamic and static scintigraphy after peritumoral administration of ^99mTc-nanocolloid. Subsequently, Lipiodol^® was administered at the same injection sites, followed by fluoroscopy and CT acquisition. Finally, late scintigraphy and SPECT/CT were conducted, enabling the fusion of late CTL and SPECT imaging. The next day, designated SLNs were harvested, radiographically examined for Lipiodol^® uptake and histopathologically assessed. Corresponding images of CT, ^99mTc-nanocolloid lymphoscintigraphy and SPECT/late CTL fusion were evaluated. ^99mTc-nanocolloid lymphoscintigraphy identified 21 SLNs, of which 7 were identified with CTL (33%). CTL identified no additional SLNs and failed to identify any SLNs in four patients (40%). Out of six histopathologically positive SLNs, two were identified by CTL (33%). Radiographic examination confirmed Lipiodol^® uptake in seven harvested SLNs (24%), of which five were depicted by CTL. CTL using Lipiodol^® reached a sensitivity of 50% and a negative predictive value (NPV) of 75% (median follow-up: 12.3 months). These results suggest that CTL using Lipiodol^® is not a reliable technique for SLN mapping in early-stage oral cancer.

Sentinel node biopsy in node negative early oral cancers: Solution to the conundrum!

Ideal management of the node-negative neck in early oral cancers is a debated issue. Elective neck dissection (END) is recommended in these patients as it offers a survival benefit. However, about 50-70% of patients who do not harbor occult metastasis are overtreated with this approach. Surgery is associated with morbidity, predominantly shoulder dysfunction. Numerous attempts have been made to identify true node-negative patients through imaging and prediction models but none have high diagnostic accuracy to safely spare the neck dissection. The recent publications of 2 large randomized controlled trials comparing the outcomes of sentinel node biopsy (SNB) and END have spurred interest in SNB. Both the trials reported SNB to be an oncologically safe procedure and spared unnecessary neck dissections. The functional outcomes of the trials showed that SNB limits the morbidity compared to END, which albeit evens out at the end of one-year post-surgery. Despite its benefits, SNB has failed to gain widespread acceptability due to various limitations including the need for infrastructure, equipment costs, staff, and multidisciplinary collaboration of nuclear medicine, surgical, and pathology fraternity. The labor-intensive pathology protocol with serial step sectioning and immunohistochemistry poses a challenge to the feasibility at a high-volume center. This perspective discusses these limitations and propose plausible solutions to the conundrum. To make it widely applicable and feasible across the globe efforts should be directed to understand biology better, find novel solutions, and implement the lessons learned over decades from other sites.

Efficacy of different sentinel lymph node biopsy protocols in oral squamous cell carcinoma: Systematic review and meta-analysis

The sentinel node biopsy (SNB) is highly protocolized in other cancers, however, this is not the case for oral squamous cell carcinoma patients, hence our objective was to evaluate the different protocols published. A specific study protocol was designed and subsequently registered on PROSPERO (Ref. CRD42021279217). Twenty‐three articles were included in the meta‐analysis. The grouped sensitivity of the SNB was 82% (95% CI: 0.74–0.88), and the grouped specificity was 100% (95% CI: 0.99–1.00). The use of other radiotracers other than pre‐operative lopamidol showed higher values of sensitivity of 82.80% (95% CI: 76.90%–87.50%; p < 0.001). The use of the blue dye stain showed higher sensitivity values of 85.60% (95% CI: 71.90%–93.20%), compared to sensitivity values of 77.50% when it was not used (95% CI: 69.10%–84.20%) (p < 0.001). Diagnostic rates are variable and they were significantly better when 99mTc was used in all its variations and accompanied by the blue dye staining.

Centralised pathology service for sentinel node biopsy in oral cavity cancer: The Southeast England Consortium experience

BACKGROUND

Sentinel lymph node biopsy is an increasingly recognised option for accurate staging and subsequent management of the clinically negative neck in early stage oral cavity squamous cell carcinoma. However, the technique is currently underused due to several logistic constraints including increased burden on pathology services. Here, we describe the feasibility of an outsourced centralised pathology processing and reporting service for sentinel lymph node biopsies in oral cavity squamous cell carcinoma.

PATIENTS AND METHODS

The Southeast England Consortium comprises four surgical centres utilising a central pathology service. Consecutive cases between January 2016 and February 2020 were retrospectively evaluated for survival outcomes and laboratory turnaround times.

RESULTS

Twenty-eight per cent from a cohort of 139 patients had positive sentinel nodes. There was a trend towards greater overall, disease-free and disease-specific survival (OS, DFS and DSS, respectively) in sentinel node negative compared to sentinel node positive patients, but these differences were not statistically significant. The sensitivity, negative predictive value and false negative rate were 92.8%, 97.0% and 6.8%, respectively. The mean and mode laboratory TAT were 5 and 4 working days, respectively.

CONCLUSION

An outsourced centralised pathology service is a feasible option to widen the availability of sentinel node biopsy in oral cavity squamous cell carcinoma.

Serial step sections at narrow intervals with immunohistochemistry are required for accurate histological assessment of sentinel lymph node biopsy in oral squamous cell carcinoma

BACKGROUND

Sentinel lymph node (SLN) biopsy is an accurate staging modality in early oral squamous cell carcinoma (OSCC), but its accuracy relies on labor-intensive histopathology protocols. We sought to determine whether serial step sections with immunohistochemistry (SSSIHC) at narrow intervals of the entire SLN are required to accurately exclude metastasis.

METHODS

Consecutive SLN biopsies over a 13-year period were retrospectively evaluated. If the index section was negative for carcinoma, the entire SLN was subjected to SSSIHC at 150 μm intervals. The first section level and total number of section levels to contain carcinoma were recorded.

RESULTS

One hundred and eighteen SLN+ from 90 patients were included. SSSIHC upstaged the nodal status in 19.5% of patients. Metastasis was identified in 16.7% and 10.2% beyond section levels 4 and 6, respectively. Among SLNs requiring SSSIHC, 47.5% contained carcinoma in a single section level.

CONCLUSION

SSSIHC of the entire SLN at 150 μm intervals are required to identify occult metastasis in OSCC.