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Background: The mechanism underlying the malignant transformation of inverted papilloma (IP) has not yet been elucidated.Methods: To clarify the genes responsible for the malignant transformation, we analyzed 10 cases of IP, 8 of IP with dysplasia, and 11 of squamous cell carcinoma (SCC) by targeted amplicon sequencing.Results: The number of mutant genes increased in the order of IP < dysplasia < SCC. Significant differences were observed in the mutation rates of three genes (KRAS, APC and STK11) in particular. TP53 was altered frequently in each group and might be involved in malignant transformation based on to the site of the mutation. A comparison of the genetic variants by region of IP tissue among patients with IP alone, and those with dysplasia or SCC revealed significant differences in the mutation rate of the KRAS gene.Conclusion: Identification of genetic mutations in KRAS is effective for predicting the malignant transformation of IP. [ABSTRACT FROM AUTHOR]

Background: The revised 8th edition of the AJCC/UICC staging system was released in January 2017, and depth of invasion (DOI) was added to the new criteria for T classification in oral cavity cancer. In this study, we evaluated whether the 8th edition presents the prognosis and risk of nodal metastasis in patients with squamous cell carcinoma of tongue more accurately than did the 7th edition.Methods: The data for 112 patients were obtained and reclassified based on the criteria presented in the 8th edition.Results: Seven patients previously staged as T1 based on the criteria in the 7th edition were reclassified as T2 based on the 8th edition, while 19 T2 patients were reclassified as T3, and 9 T4a patients were reclassified as T3. T3 in the 8th edition represents a homogenous population showing the same prognosis, while T2 in the 8th edition represents a heterogenous population. Nodal metastasis was significantly correlated with T classification in both editions and DOI. However, neither the T classification in the 7th or 8th edition, nor DOI could predict the probability of potential nodal metastasis in patients with cN0 disease.Conclusions: The classification on T3 in the 8th edition can be seen as reasonable with regard to prognosis. Nodal metastasis was significantly correlated with T classification and DOI; however, the probability of subsequent nodal metastasis in patients with T2N0 was almost same for the criteria in the 7th and 8th editions, therefore, the same careful management as before is required for patients with N0 disease. [ABSTRACT FROM AUTHOR]