Sublingual Lymph Node Metastasis in Early-Stage Floor of the Mouth Carcinoma

Regional metastasis to anatomies beyond traditional neck dissection boundaries: a multi-institutional analysis focused on unconventional metastases in oral cancer patients

Background

Regional metastasis sometimes occurs in anatomies that are not included in traditional neck dissections. The purpose of this study was to evaluate the treatment outcomes of squamous cell carcinoma of oral cavity (SCCOC) patients with unconventional metastatic lymph nodes (UMLNs) in sublingual, buccinator, and parotid anatomies.

Methods

This retrospective multi-institutional analysis of squamous cell carcinoma of oral cavity patients with unconventional metastatic lymph nodes was performed from January 2008 to December 2015. All the included patients received surgical treatment for unconventional metastatic lymph nodes. The end point of the study was to determine the factors influencing these patients’ survival and the corresponding solutions to improve survival. Pathological grade, contralateral metastasis, extranodal extension, and other factors were collected and analyzed by logistic regression and the Cox model.

Results

A total of 89 patients were identified. Among these patients, 25 (28.1%) received primary treatment, 28 (31.5%) received staged (therapeutic) neck dissections, and 36 (40.4%) had recurrent or residual diseases. Altogether, 45 patients (51%) had buccinator node metastases, 31 (35%) had sublingual metastases, 12 (14%) had parotid metastases, and 1 had both buccinator and parotid metastases. Regarding regional metastases, 31 patients (34.8%) had isolated unconventional metastatic lymph nodes. Adjuvant therapies were administered to 72 (80.9%) patients, 25 (28.1%) of whom were treated with radio-chemotherapies. The overall survival rate was 38.2%. Multivariate analysis found that the subsites of unconventional metastatic lymph nodes (P = 0.029), extranodal extension in both unconventional metastatic lymph nodes (P = 0.025) and cervical lymph nodes (P = 0.015), sites of primary or recurrent squamous cell carcinoma of oral cavity (P = 0.035), and types of neck dissections (P = 0.025) were significantly associated with overall survival.

Conclusions

Unconventional metastatic lymph nodes are uncommon, yet awareness of potential unconventional metastatic lymph nodes should be heightened. Early surgical interventions are warranted in patients with sublingual or buccinator metastases, while caution should be given to those with parotid metastases. Aggressive en bloc (in-continuity) resections may be mandatory in advanced oral cancer cases for close anatomic locations with possible buccal or sublingual metastases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-020-02057-6.

Surgical anatomy of the lymphatic drainage of the salivary glands: a systematic review

BACKGROUND

Nodal metastasis in salivary gland malignancies has important clinical implications; a good understanding of their complex anatomy is paramount to the head and neck surgeon.

METHODS

A contemporary and comprehensive literature review was conducted of the lymphatic drainage of the salivary glands, with special emphasis on its surgical applications.

RESULTS

The parotid gland has extraglandular and intraglandular nodes acting as a single functional drainage unit. Intraglandular parotid notes are unique to the parotid gland, and consist of a larger superficial group and a smaller deep group. The presence of intraglandular submandibular nodes, as described by early anatomists, is much debated nowadays. The sublingual glands drain to the lingual lymph nodes, which are divided into median, intermediate and lateral groups.

CONCLUSION

This review highlights the complex arrangements of lymph nodes draining the salivary glands. It may provide a valid anatomical explanation for the nodal metastasis patterns commonly seen in salivary gland malignancy.

Lingual lymph nodes: Anatomy, clinical considerations, and oncological significance

Lingual lymph nodes are an inconstant group of in-transit nodes, which are located on the route of lymph drainage from the tongue mucosa to the regional nodes in neck levels I and II. There is growing academic data on the metastatic spread of oral cancer, particularly regarding the spreading of oral tongue squamous cell carcinoma to lingual nodes. These nodes are not currently included in diagnostic and treatment protocols for oral tongue cancer. Combined information on surgical anatomy, clinical observations, means of detection, and prognostic value is presented. Anatomically obtained incidence of lingual nodes ranges from 8.6% to 30.2%. Incidence of lingual lymph node metastasis ranges from 1.3% to 17.1%. It is clear that lymph nodes that bear intervening tissues from the floor of the mouth should be removed to improve loco-regional control. Extended resection volume, which is required for the surgical treatment of lingual node metastasis, cannot be implied to every tongue cancer patient. As these lesions significantly influence prognosis, special efforts of their detection must be made. Reasonably, every tongue cancer patient must be investigated for the existence of lingual lymph node metastasis. Lymphographic tracing methods, which are currently implied for sentinel lymph node biopsies, may improve the detection of lingual lymph nodes.

Guidelines for the Surgical Management of Oral Cancer: Korean Society of Thyroid-Head and Neck Surgery

Korean Society of Thyroid-Head and Neck Surgery appointed a Task Force to provide guidance on the implementation of a surgical treatment of oral cancer. MEDLINE databases were searched for articles on subjects related to "surgical management of oral cancer" published in English. Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. The quality of evidence was rated with use RoBANS (Risk of Bias Assessment Tool for Nonrandomized Studies) and AMSTAR (A Measurement Tool to Assess the Methodological Quality of Systematic Reviews). Evidence-based recommendations for practice were ranked according to the American College of Physicians grading system. Additional directives are provided as expert opinions and Delphi questionnaire when insufficient evidence existed. The Committee developed 68 evidence-based recommendations in 34 categories intended to assist clinicians and patients and counselors, and health policy-makers. Proper surgical treatment selection for oral cancer, which is directed by patient- and subsite-specific factors, remains the greatest predictor of successful treatment outcomes. These guidelines are intended for use in conjunction with the individual patient's treatment goals.