Treatment Modality

Lymphatic basins at risk of metastasis can be managed effectively with either surgery or radiation therapy.3'6'10'15-18'20,22,46-58 The selection of the appropriate modality should follow other tumor parameters. In patients with locally advanced lesions requiring adjunctive treatment, the neck can be effectively managed with radiation therapy alone. Studies have shown a > 90% control rate of micrometastasis with the use of elective irradia-tion.18,22'47-49'52-54'56,57 However, several questions remain regarding the use of radiation in this setting. Critics of the use of radiation therapy note that, in addition to the lack of valuable prognostic pathologic information, the reported failure rate of 10% in the setting of elective treatment for occult metastasis indicates a 33% failure rate, as only about 30% of cases treated in this manner actually have micrometastasis. Proponents of elec tive radiation therapy counter with the finding that the control rate with radiation in patients without recurrence at the primary site is 96 to 99%, extrapolating that radiation is highly effective in the setting of N0 necks.22,53,54,56

Surgical management of the neck should be considered in patients treated surgically for primary lesions that do not require adjunctive radiation. The extent of neck surgery should be guided by the location of the primary lesion. Given the significant functional and aesthetic morbidity after classic radical neck dissection, modifying the operation to reduce morbidity without compromising regional control rates or survival is indicated.23 In the setting of elective treatment of the neck, it is seldom necessary to perform a comprehensive neck dissection to excise all five levels of lymph nodes.1-5,23,24,52,59 Because cervical lymph node metastasis to the first echelon lymph nodes occurs in a predictable and sequential fashion, elective neck dissection can be limited to addressing only the lymph node groups at highest risk in a given primary site (Fig. 3-2). The use of selective neck dissections, instead of radical neck procedures, in the management of patients at risk of occult nodal metastasis achieves similar control rates, as confirmed in a prospective analysis. A prospective randomized study in Brazil, looking at 148 patients with oral cancers, found no differences in regional control (19 vs 16 neck failures) or survival (63% vs 67%) in patients treated with selective neck dissections as compared with those undergoing modified radical neck dissection.46 In order to achieve comparable regional control rates, however, postoperative radiation therapy should be employed for the appropriate indications, including metastasis to multiple nodes and the presence of extracapsular spread. The dissection of lymph node levels in selective neck dissections is con

Figure 3-2 First echelon lymph nodes at risk for micrometastasis in head and neck squamous cell carcinomas. (A) Removed as part of a lateral neck dissection for laryngopharyngeal primaries. (B) Removed as part of a supraomohyoid neck dissection for oral cavity primaries.

sidered a staging procedure by most investigators, although some argue that selective neck dissections may be therapeutic in certain settings.1-5'10,24'52,60 Nonetheless, the histologic information derived from the study of the excised lymph nodes facilitates selection of adjuvant therapy in patients at increased risk of neck failure, sparing the need for a morbid operation or adjuvant radiotherapy in others who are at reduced risk.

For primary tumors in the oral cavity, the regional lymph nodes at highest risk of early dissemination by metastatic cancer are limited to levels I, II, and iii.1,2,5,21,24,52,58,61 Anatomically, this translates into regional lymph node groups contained within the supraomohyoid triangle of the neck, including the submental, submandibular, prevascular facial, jugulodigastric, upper deep jugular, superior spinal accessory chain of lymph nodes, and mid-jugular lymph nodes. Skip metastasis to levels IV and V in the absence of metastatic disease at levels I, II, or III occurs in fewer than 5% of cases at the time of the initial procedure.1,2,21,58 Therefore, if the neck is clinically negative, level IV and V lymph nodes are generally not at risk of harboring micrometastasis from primary squamous cells carcinomas of the oral cavity. The distribution of metastasis can be evaluated effectively by means of a supraomohyoid neck dissection.

Several investigators have questioned the true extent of nodal excision in a supraomohyoid neck dissection. One study questioned the benefit of dissection of the supraspinal accessory lymph nodes as part of the procedure, reporting only a single case in which metastasis was identified in this region, which also contained coexistent metastasis at level II of the neck.62 Dissection and retraction along the accessory nerve can be minimized if the supraspinal accessory nodes do not require excision, but this limitation in dissection requires further corroboration. A study conducted by Byers et al.63 reported a failure rate of 15% outside the traditional confines of a supraomohyoid neck dissection. These workers advocated the extension of the neck dissection to include level IV of the neck. The efficacy of this extension in limiting neck nodal recurrence needs to be confirmed.

For tumors on the lateral aspect of the oropharynx, hypopharynx, and larynx, the first echelon lymph nodes at highest risk of harboring micrometastasis in the clinically negative neck are the deep jugular lymph nodes at levels II, III, and IV on the ipsilateral side.1,3,21 The lymph node groups in the deep jugular chain are jugulodigastric, highest spinal accessory chain of lymph nodes, mid-jugular lymph nodes, juguloomohyoid lymph nodes, and supraclavicular lymph nodes deep to the ster-

nocleidomastoid muscle. Contiguous lymph nodes lateral to the internal jugular vein overlying the cutaneous roots of the cervical plexus are usually considered a component of levels II, III, and IV. In patients with primary carcinoma of the oropharynx with a clinically negative neck the risk of micrometastasis to levels I and V is exceedingly low. Skip metastasis to levels I and V in the absence of disease at levels II, III, or IV is usually not seen. Primary tumors that involve both sides of the midline have a potential of microscopic dissemination of metastatic disease to jugular lymph nodes on both sides of the neck. A jugular or lateral neck dissection, which encompasses the removal of all lymph nodes in levels II, III, and IV in the neck, is ideally suited for tumors in these anatomic locations.

Overall, selective neck dissections in patients with NO neck provide accurate pathologic staging of the regional lymph nodes at risk of having micrometastasis and offer regional control rates comparable to those obtained with more radical operative procedures.

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