Molecular and clinicopathological analyses of esophageal carcinosarcoma with special reference to morphological change.

The molecular pathogenesis of esophageal carcinosarcoma (ECS) has not been fully investigated. This study includes 16 consequent cases of surgically resected ECS. Genetic alterations were independently examined for carcinoma in situ, carcinomatous, and sarcomatous areas. Six cases were analyzed by next-generation sequencing, and the remaining cases were analyzed by Sanger sequencing for TP53, PTEN, and INI1. Sarcomatous components in 3 cases showed histologically heterogenous feature of osteosarcoma. Lymph node metastasis was found in 12 out of 16 cases. Survival analysis revealed 5-year overall survival rate of 59.9%, and the median survival time was 5.37 years. TP53 was the most frequently mutated gene, being identified in 11 of 16 patients (68.8%), 7 of whom (63.6%) had the same mutations in both carcinomatous and sarcomatous areas. Almost complete concordance was found between p53 immunohistochemistry and TP53 missense mutations. Five-year overall survival tended to be worse for patients with p53 overexpression, although the data was not significant (p = 0.186). Nine of 16 patients (56.3%) showed loss of heterozygosity (LOH) at the INI1 locus, and this LOH status was consistent with both components. However, interestingly, INI1 expression was preserved in all cases. In addition, copy number variation analysis revealed gene amplification in several tyrosine kinase receptors. Accumulation of mutations in tumor suppressor genes such as TP53 and INI1 seemed to occur during ECS development.