Extent of Surgery

In order for END to provide the most accurate staging information possible, the procedure must thoroughly remove the cervical lymphatics, which potentially harbor metastatic disease. Radical neck dissection (RND) was the procedure that was routinely employed for elective lymphadectomy when surgeons first began performing END. Careful examination of RND specimens according to the zone in the neck demonstrated that regional metastatic patterns could be predicted on the basis of the site and stage of the primary tumor.23'29 Selective neck dissection (SND), which removes only the lymphatic zones at risk of the primary lesion and preserves major structures, has evolved as a result of these studies. By limiting the extent of surgery, selective procedures significantly decrease the morbidity and mortality, as compared with radical neck dissection.

Head and neck surgeons have examined regional recurrence rates and the location of regional recurrences in an effort to determine whether selective neck dissections constitute adequate procedures for staging the NO neck.

Retrospective studies reporting the regional recurrence rate after selective and comprehensive procedures for END have shown that regional recurrences average approximately 5% for either procedure.21,22,31,32 Comparisons between studies are difficult because of the time span over which they were performed. For instance, postoperative radiation therapy for the pN+ neck was not uniformly used in many of the early studies. Institutional differences in treatment philosophies also make comparisons between studies difficult. Studies that have directly compared comprehensive with selective procedures within the same institution confirm a similar regional recurrence rate between the two procedures.24

For selective procedures to achieve adequate nodal sampling and regional control, the zones at risk of occult metastases must be totally dissected. Critical assessment of the location of regional recurrences after SND has contributed to our understanding of the lymphatics considered to be at risk. Early experience with selective procedures led to understanding that the area posterior to the jugular vein and anterior to the cervical rootlets (level III to IVb) must be thoroughly dissected.33,34 Other areas that merit consideration depending on the location of the primary tumor are the area surrounding the spinal accessory nerve at level II, level IV for oral cavity lesions,35 and the subsites of the submandibular zone.11 The retropharyngeal nodes may be at risk of some primary sites but are not routinely addressed by any standard procedure. The risk of metastases outside the zones at risk is probably extremely small. Therefore, selective procedures, if carefully performed, constitute adequate nodal sampling.

0 0

Post a comment