Extent of lymphadenectomy achieved by various modifications of neck dissection: A pathologic analysis

Objectives: Quantify the extent of lymphadenectomy achieved by the various modifications of neck dissection based on microscopic pathologic analysis, Study Design: Retrospective review of neck specimens of patients who underw ent neck dissection for head and neck malignancies at our institution over a 5-year period. Methods: Charts and pathology report findings on patients who underwent neck dissection were reviewed. Patients who received preopera tive chemotherapy or radiation therapy to the neck were excluded. The numbe r of lymph nodes documented by pathologic microscopic examination for each specimen was recorded. Results: There were 164 neck specimens on 135 patien ts (29 patient had simultaneous bilateral neck dissection). Those were divi ded into four groups based on the nonlymphatic structures preserved. There were 58 radical neck dissections (radical neck dissections) (group 1), 50 m odified radical neck dissections sparing the eleventh cranial nerve (group 2), 15 modified radical neck dissections sparing the eleventh cranial nerve and internal jugular vein (group 3), and 33 modified radical neck dissecti ons sparing the eleventh cranial nerve, internal jugular vein, and sternocl eidomastoid muscle (group 4), The remaining 8 had other modifications of ra dical neck dissection, The mean number of lymph nodes found per specimen wa s 34 in group 1, 27 in group 2, 31 in group 3, and 22 in group 4, We perfor med one-way between-group analysis of variance (ANOVA), Pair-wise compariso ns of means were carried out subsequent to ANOVA utilizing the Fisher Exact Test. Group 4 was significantly different from all other groups. Additiona lly, group 2 significantly differed from group 1. Conclusions: The extent o f lymphadenectomy achieved by neck dissection decreases as the number of no nlymphatic structures preserved in the neck increases. The impact of this f inding on the pathologic staging or prognosis needs further analysis.