Is Selective Neck Dissection Adequate Treatment for Node-Positive Disease?

Abstract

Selective neck dissection, or the selective removal of nodal groups at risk for harboring cervical metastases, is an extension of the concept of the functional neck dissection first introduced in the 1960s. Until 1963, radical neck dissection (RND) was the standard surgical treatment of the cervical lymphatic nodes. In 1963 Suarez proposed a conservative, functional approach to neck dissection that was popularized by Bocca et al. These authors described the removal of cervical lymph nodes from levels I through V with their enveloping fascial sheath while sparing nonlymphatic anatomic structures adjacent to, but not containing, lymph nodes, such as the accessory nerve, internal jugular vein, and sternocleidomastoid muscle. The resulting modified RND (MRND) has been shown to avoid the cosmetic and functional morbidity associated with the classic RND without compromising oncologic safety or efficacy as a staging and therapeutic procedure. Various modifications of the functional or MRND have been proposed for the elective treatment of the clinically negative neck (cN0) when surgical treatment of the primary tumor is planned and the risk of occult metastases is greater than 20%. Selective neck dissections are based on the observation that tumors of the upper aerodigestive tract drain to predictable nodal levels according to the site of the primary tumor, and that a comprehensive neck dissection encompassing all 5 nodal levels may therefore be unwarranted. The incidence of occult metastases in the cN0 neck exceeds 20% for tumors arising from the oral cavity, oropharynx, hypopharynx, and supraglottic larynx. The presence of cervical metastases is associated with a poorer prognosis. Accurate detection of occult metastases is difficult, as approximatively 50% of occult metastases are less than 5 mm and missed on physical and radiologic examination. Extracapsular spread may be present in as many as 50% of patients with occult metastases. If neck dissection is performed therapeutically when neck disease becomes clinically apparent, survival and surgical salvage rates are significantly decreased. An appropriately selected SND, which removes lymph nodes only at the levels likely to harbor metastatic disease, provides important prognostic information and, in some circumstances, may be therapeutic. In a review of 1119 RNDs performed electively for cN0 neck disease and therapeutically for clinically node-positive neck disease, Shah found that occult metastases were present in 33% of elective neck dissections and that level V was never involved in the absence of involvement of other nodal levels. Levels I, II, and III were at greatest risk for nodal metastases from squamous cell carcinoma of the oral cavity, and levels II, III, and IV were at greatest risk for metastases from carcinomas of the oropharynx, hypopharynx, and larynx. These findings support the use of supraomohyoid neck dissection (removing lymph nodes from levels I through III) for patients with cN0 oral cavity tumors in cN0 patients and anterolateral neck dissection (removing lymph nodes from levels II through IV) in patients with cN0 tumors of the oropharynx, hypopharynx, and larynx. Byers et al have shown that “skip metastases” to level IV occur in 16% of patients with squamous cell carcinoma of the oral tongue and advocate removal of level IV nodes as part of SND for oral tongue cancer. The regional recurrence rate following SND alone in patients with histologically negative nodes (pN0) is approximately 5%, which compares favorably with the rate in patients undergoing MRND for clinically and histologically negative nodal disease. It is generally accepted that SND is as effective as comprehensive neck dissection in staging the cN0 neck and is adequate treatment for the pN0 neck. The therapeutic efficacy of SND in patients with pathologic node-positive neck disease, however, is more controversial. Data Christine G. Gourin, MD