Background: Salivary duct carcinoma (SDC) is associated with aggressive clinical behavior.
Methods: We examined the prognostic values of clinicopathologic variables and hypoxia biomarker expression in 21 patients with SDC treated by resection with/without neck dissection and radiotherapy. Tissue microarrays constructed from tumor blocks were stained with monoclonal antibodies to hypoxia-inducible factor (HIF)-1alpha, HIF-2alpha, carbonic anhydrase-9, glucose transporter-1, and erythropoietin receptor. Locoregional control and survival rates were calculated by the Kaplan-Meier method and prognostic factors were calculated from uni- and multivariate analyses.
Results: The cervical nodal metastasis rate was 67% at initial diagnosis and the distant metastasis rate was 71% during follow-up. The only significant predictor of distant metastasis was nodal metastasis (P = 0.006). Actuarial 5-year locoregional control, distant metastasis-free survival, and overall survival rates were 57%, 40%, and 44%. Multivariate analysis showed that lymphovascular and perineural invasion and radiotherapy were independent predictors of overall survival (P < 0.025). None of the hypoxia biomarkers, however, was a significant predictor of locoregional control, distant metastasis, or survival.
Conclusions: Lymphovascular and perineural invasion, but not hypoxia biomarkers, were significant prognostic factors for patients with SDC.