Incompletely treated malignancies of the major salivary gland: Toward evidence-based care.

BACKGROUND: Unexpected malignancy is common in major salivary gland tumors due to variability of workup, creating challenging treatment decisions. The purpose of this study was to define treatment-related outcomes for patients with incompletely treated major salivary gland tumors. METHODS: A retrospective cohort study was completed of patients with incompletely treated major salivary gland tumors. Tumor burden at presentation was established and treatment categorized. The Cox Proportional Hazards model was used to determine predictors of survival and failure. RESULTS: Of the 440 included patients, patients with gross residual or metastatic disease had a worse overall survival (OS; P < .001). Presentation status was an independent predictor of OS on multivariate analysis (gross residual disease adjusted hazard ratio [HRadjusted ] 2.55; 95% confidence interval [CI] 1.20-5.30; metastatic disease HRadjusted 9.53; 95% CI 3.04-27.06). CONCLUSION: Failure to achieve gross total resection during initial surgery resulted in worse OS. Adequate preoperative planning is required for initial surgical management to optimize tumor control and survival.

Intercellular Genetic Interaction Between Irf6 and Twist1 during Craniofacial Development.

Interferon Regulatory Factor 6 (IRF6) and TWIST1 are transcription factors necessary for craniofacial development. Human genetic studies showed that mutations in IRF6 lead to cleft lip and palate and mandibular abnormalities. In the mouse, we found that loss of Irf6 causes craniosynostosis and mandibular hypoplasia. Similarly, mutations in TWIST1 cause craniosynostosis, mandibular hypoplasia and cleft palate. Based on this phenotypic overlap, we asked if Irf6 and Twist1 interact genetically during craniofacial formation. While single heterozygous mice are normal, double heterozygous embryos (Irf6 +/- ; Twist1 +/- ) can have severe mandibular hypoplasia that leads to agnathia and cleft palate at birth. Analysis of spatiotemporal expression showed that Irf6 and Twist1 are found in different cell types. Consistent with the intercellular interaction, we found reduced expression of Endothelin1 (EDN1) in mandible and transcription factors that are critical for mandibular patterning including DLX5, DLX6 and HAND2, were also reduced in mesenchymal cells. Treatment of mandibular explants with exogenous EDN1 peptides partially rescued abnormalities in Meckel's cartilage. In addition, partial rescue was observed when double heterozygous embryos also carried a null allele of p53. Considering that variants in IRF6 and TWIST1 contribute to human craniofacial defects, this gene-gene interaction may have implications on craniofacial disorders.