Elsevier

Oral Oncology

Volume 44, Issue 3, March 2008, Pages 216-219
Oral Oncology

REVIEW
Elective supraomohyoid neck dissection for oral cavity squamous cell carcinoma: Is dissection of sublevel IIB necessary?

https://doi.org/10.1016/j.oraloncology.2007.06.006Get rights and content

Summary

Spinal accessory nerve (SAN) dysfunction and related shoulder disability are common consequences of supraomohyoid neck dissection (SOHND). Nerve dysfunction is usually attributed to excessive nerve traction or devascularization during clearance of the lymph nodes posterior and superior to the SAN (sublevel IIB). The need for routine dissection of this sublevel with elective neck dissection has recently been questioned. This review article discusses whether preserving sublevel IIB lymph nodes is justified in elective SOHND for patients with squamous cell carcinoma (SCC) of the oral cavity. A review of the literature was conducted on studies of sublevel IIB dissection in elective SOHND for SCC of the oral cavity. Only two studies have prospectively investigated the incidence of lymph node metastasis in patients with clinically N0 SCC of the oral cavity. Data from these two prospective pathologic and molecular analyses of neck dissection specimens, including 122 patients with N0 oral cancer, revealed 7.3% with positive neck nodes at sublevel IIB for oral cancer in general, and 12% for tongue cancer in particular. When considering the merits of preservation of sublevel IIB, the benefit of preservation of SAN function has to be weighed against potentially reduced oncologic control.

Introduction

The presence of cervical lymph node metastasis is the single independently most adverse prognostic factor in squamous cell carcinoma (SCC) of the oral cavity. The incidence of occult regional lymph node metastasis in such tumors varies from 6% to 46% in different series.1 Traditional techniques of pathologic analysis of neck dissections are potentially flawed and may miss micrometastases and soft tissue deposits.2, 3, 4

Conflicting rationales exist regarding the most appropriate therapeutic management of a clinically negative neck. Results of studies on the nodal pattern of spread of SCC of the oral cavity showed that regional metastases are generally located in levels I–III, while the risk of a levels IV or V lymph node metastasis is extremely low. Therefore, supraomohyoid neck dissection (SOHND), which refers to the removal of lymph nodes contained in levels I–III, has become the standard of care for elective management of clinically N0 necks in patients with SCC of the oral cavity.5

Elective neck dissection has proved to be beneficial in early stages of oral cancer. Different series have shown that patients in stages I and II who underwent elective neck dissection had a 21–27% higher disease-free survival rate compared with those who underwent resection of the tumor alone, further supporting the fact that elective neck dissection significantly improves survival.1, 6, 7

To better identify patients with stages I and II oral cancer who are at high risk of having occult cervical nodal disease, various tumor and patient factors have been correlated with the presence or absence of pathologically positive nodes in patients undergoing node dissection. Tumor thickness has been the most consistent predictive factor of occult neck metastasis in multivariate analyses of patients with tongue carcinoma.8, 9, 10, 11 Clark et al.11 reported 10% and 46% incidence of regional disease in thin (⩽5 mm) and thick (>5 mm) tumors, respectively. Other clinicopathologic factors significantly associated in multivariate studies with the development of cervical lymph node metastasis have been the presence of perineural invasion, an infiltrating-type invasion front, and poorly differentiated tumors.10, 12 Immunohistochemical biomarkers potentially predicting late cervical metastasis in stages I and II oral tongue carcinomas have been investigated. Lim et al.9 studied the immunohistochemical expression of a battery of 10 genes and proteins, and reported that a low expression of E-cadherin was the only independent predictor of a high risk for late cervical metastasis. The usefulness of E-cadherin as an independent marker of neck metastasis has been confirmed by others.13, 14 Vascular endothelial growth factor has recently been shown to be a valuable biomarker to predict cervical metastasis in patients with early oral cavity cancer.15

The present review discusses whether it is reasonable to spare sublevel IIB lymph nodes in SOHND for patients undergoing elective neck dissection for SCC of the oral cavity in order to avoid the associated potential morbidity relating to spinal accessory nerve (SAN) dysfunction.

Section snippets

Anatomy of sublevel IIB

The lymph nodes of the neck can be divided into 6 levels. The boundaries of level II extend from the level of the skull base superiorly to the level of the lower border of the hyoid bone inferiorly. The anterior (medial) boundary of level II is the posterior belly of digastric/stylohyoid muscle and the posterior (lateral) boundary is the posterior border of the sternocleidomastoid muscle. The levator scapula and splenius capitis muscles form the bed of this anatomical area.16, 17 Level II lymph

Sublevel IIB and the SAN

A variety of morbidities are associated with SOHND, one of which is shoulder dysfunction. This may be due to traction, elevation or electrocautery injury to the SAN during dissection of sublevel IIB or due to ischemia of the nerve caused by the ligation of the occipital artery, or one of its branches supplying the nerve.18, 19

Kraus et al.19 reported that 50% of patients who underwent SAN-sparing procedures experienced shoulder drop while 30% of those patients who underwent a minimal SAN

Studies of sublevel IIB lymph node status in neck dissections for clinically N0 oral SCC

Prospective multi-institutional pathologic and molecular studies of neck dissection specimens have attempted to specifically investigate the incidence of lymph node metastasis to sublevel IIB. Although some prospective studies18, 22, 23 are very informative, they have been excluded because none of them presented a homogeneous study group (N0 and N+ necks were considered without distinction) or the data were incomplete. Taking this into consideration, only the following two studies can be

Discussion

Accurate staging of cervical lymph node status is important in terms of treatment and prognosis.25 The identification of (N+) patients at high risk of recurrence will spare those at lower risk of recurrence (N−) from the morbidity of unnecessary treatment while also appropriately identifying aggressive tumors that warrant adjuvant therapy despite their early clinical stage. It is generally accepted that elective treatment of the neck is required when the risk of occult cervical lymph node

Conclusion

Data from two prospective pathologic and molecular analyses of neck dissection specimens of 122 patients with N0 oral cancer revealed 7.3% with positive neck nodes at sublevel IIB for oral cancer in general, and 12% for tongue cancer in particular.21, 24 When considering the merits of preservation of sublevel IIB, the benefit of preservation of SAN function has to be weighed against potentially reduced oncologic control. Until such time as more studies have been done to clarify the incidence of

Conflict of Interest Statement

None declared.

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  • Cited by (21)

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