Neck lymph node metastases to the posterior triangle APEX: Evaluation of clinical and histopathological risk factors

Background. Dissection of posterior triangle apex (APEX) is a surgical step in supraomohyoid and lateral neck dissections. The prevalence of lymphatic metastases at this site and the clinicohistopathologic conditions that inf luence their occurrence have not been established. We have evaluated the pr evalence and the risk factors for cervical metastases in lymph nodes of the APEX. Methods. Sixty-two neck dissections were performed in 51 patients with squa mous cell carcinoma of the oropharynx, hypopharynx, oral cavity, glottic la rynx, and supraglottic larynx or with primary occult tumor. We correlated t he presence of positive metastases in the APEX with the neck level involved either clinically (CLIN) or histopathologically (H/P) and with the number of CLIN- or H/P-positive neck levels with metastases. The prevalence of met astases in the APEX in elective (NO) and therapeutic (N+) neck dissections was also compared. This prevalence was also compared with that for each nec k level. The histopathologic comparisons between the APEX and the neck leve ls were calculated for NO, N+, and all neck dissections. The primary site o f tumor was correlated with the presence of H/P-positive nodes in the APEX. Results. The overall prevalence of lymphatic metastases in the APEX was 6.5 %. The prevalence in NO neck dissections was 2.3% and in N+ neck dissection s it was 16.7%. The prevalence of lymphatic metastases in the APEX for prim ary tumors of pharynx was 23.1%, for the oral cavity it was 3.6%, and it wa s 0% for other sites. Metastases in the APEX were not influenced by the nec k level with CLIN or H/P metastases in N+ necks. The number of CLIN- or H/P -positive neck levels had no influence on histopathologic metastases in the APEX. Factors that influenced metastases in the APEX were positive histopa thologic metastases at level II for NO neck dissections and positive histop athologic metastases at level II or III for all neck dissections. All the c omparisons were analyzed using Fisher's or Poisson's test. Conclusions. The prevalence of histopathologic metastases in the APEX in N necks is 7.3 times greater than that of NO necks and for primary tumors of pharynx it was 6.4 times greater than for the oral cavity and significantl y greater than for the larynx. Histopathologic metastases at level II for c linically NO necks and histopathologic metastases to level II or III for al l neck dissections are risk factors for metastases in the APEX. The number of positive levels did not influence the prevalence of metastases in the AP EX. There are no isolated metastases in the APEX of the posterior triangle. (C) 2000 John Wiley & Sons, Inc.