Acetylated tubulin and risk of nodal metastases in squamous cell carcinoma of the head and neck (SCCHN)

5560 Background: We previously established that AT expression predicts for response to chemotherapy in SCCHN (Saba et al, AACR 2010 meeting abstr 3744). We wanted to further examine the relation of AT expression and nodal metastases in SCCHN. Methods: We assessed AT expression in archival tissue specimens from primary SCCHN cases with (50 cases) and without (53 cases) lymph node metastases (NM) using standard immunohistochemistry (IHC). Clinical characteristics of patients were retrieved from the department of pathology under the guidelines of the institutional review board (IRB). IHC staining for AT was scored based on intensity and percentage of tumor cells stained: 0 = no staining, 1+ = weak, 2+ = moderate, 3+ = moderate to high, 4+ = high and a weighted index (WI) was calculated as percent stain x stain intensity. Wilcoxon two-sample test and Kruskal-Wallis test were used to estimate the relationships of the WI with nodal metastasis, node status, primary tumor location, grade, and stage. Log-rank test was used to examine the difference in OS and DFS among four groups based on quartiles of the WI. A Cox proportional hazard model was employed to estimate the adjusted effect of WI on OS and DFS. Results: A higher AT expression was associated with nodal metastasis (p=0.0155) and higher stage (p=0.0311). A lower AT expression was associated with oral cavity primary (p=0.0107). After adjusting for age, gender, race, and smoking status, a lower AT expression was significantly associated with better DFS in the subset of patients with NM by multivariate analysis (HR=1.008; 95% CI=1.002- 1.014; p=0.0123). Among patients with no NM there was a marginally significant difference in OS among four different groups based on quartiles of AT expression (p=0.0765). Conclusions: High AT expression is associated with nodal metastases in SCCHN and may be a marker of poor prognosis in patients with node positive disease. The value of AT as a prognostic marker in SCCHN needs to be better defined. This work is supported by a SPORE CDP Grant P50 CA128613-03 to NFS.