Cytokeratin immunohistochemically detected nodal micrometastases in N0 laryngeal cancer: impact on the overall occult metastases

The objective of this study is to evaluate the incidence of occult nodal micrometastases in N0 laryngeal squamous cell carcinoma using cytokeratin immunohistochemical analysis (CKIHA) and its influence on the overall occult metastatic rate. This is a prospective cohort study. A total number of 30 patients with N0 stage laryngeal cancer underwent 46 selective neck dissections for elective treatment of the neck. Nodes found to be negative using routine histopathological examination were evaluated for the presence of micrometastasis using CKIHA. The occult micrometastasis rate for all cases was 26.7 % which significantly increased the overall occult metastasis rate to 50 % (P = 0.014). The micrometastasis rate was 30.8, 25 and 20 % for glottic, supraglottic and transglottic tumors, respectively, which increased the overall occult metastasis rate to 53.8, 50 and 40 % but without statistical impact. The micrometastasis rate was 35.7 and 23.1 % in T3 and T4 tumors, respectively, and this increased the overall occult metastasis rate to 50 and 61.5 % with statistical influence in T3 tumors (P = 0.046). Micrometastasis upstaged the neck in 7 (23.3 %) patients with statistical impact on the PN stage (P = 0.007). The overall occult nodal metastasis rate in N0 laryngeal cancer is underestimated. Nodal micrometastasis may be missed during routine histopathological examination and can be detected using CKIHA.