Methods in molecular biology
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Histological assessment of esophageal squamous malignancies is crucial for management of patients with the cancer as well as working in research on the cancer. The squamous malignancies in the esophagus comprise squamous dysplasia and squamous cell carcinoma. Current classification of squamous dysplasia in the esophagus is to divide it into low grade and high grade. ⋯ Preoperative chemoradiation is used commonly in the treatment of esophageal squamous cell carcinoma and induces changes in morphology. Tumor regression grading systems based on the percentage of the remaining carcinoma cells are used to assess the response to the neoadjuvant therapy in the cancer. Additional histological parameters including lymphovascular invasion, perineural invasion, clearance of resection margins, and carcinoma in the nodal and distant metastatic sites provide essential information for the management of the patient with the cancer.
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Cervical esophageal carcinoma (CEC) is rare, accounting for 2-10% of esophageal cancers and is mostly squamous cell carcinoma. Because of the anatomical proximity of CEC to larynx, surgical treatment would involve pharyngo-laryngo-esophagectomy (PLE) with inherent high mortality and morbidity. Laryngeal preservation is an important consideration, and definitive chemoradiotherapy is the recommended treatment. ⋯ Since the exact location, extent of primary and nodal metastasis varies between patients, radiotherapy treatment needs to be individualized. The optimal radiation dose for CEC is uncertain, but retrospective data suggests that higher radiation dose of at least 60 Gy is associated with better local control and survival. Advanced radiotherapy technique, like intensity modulated radiotherapy, is usually required to achieve high dose to tumor while protecting normal tissues from excessive radiation.
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Technological advances in the form of next-generation sequencing allow sequencing of large numbers of different DNA sequences in a single/parallel reaction compared to conventional sequencing. It is a powerful tool which has enabled comprehensive characterization of esophageal squamous cell carcinoma. Whole-genome sequencing is the most comprehensive but expensive, whereas whole-exome sequencing is cost-effective, but it only works for the known genes. Thus, second-generation sequencing methods can provide a complete picture of the esophageal squamous cell carcinoma genome by detecting and discovering different type of alterations in the cancer which may lead to the development of effective diagnostic and therapeutic approaches for esophageal squamous cell carcinoma.
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Pathological assessment of frozen sections of tissues is important in the clinical management (intraoperative consultation) and research in patients with esophageal squamous cell carcinoma. Frozen sections may be used in the assessment of status of resection margins, extent of cancer metastasis (pathological staging), confirmation of the pathology, and increased volume of cancer cells for tissue banking. However, the applications of frozen sections have many technical limitations. Thus, interpretation of frozen sections needs expertise, collaborations, and attention to proper technical skills in the sectioning.
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Circulating tumor cells (CTC) harvested in the blood of patients with esophageal squamous cell carcinoma (ESCC) are associated with certain clinical pathological parameters as well as patients' prognosis and response to chemoradiation. They are the source of distant metastases and their mechanisms of pathogenesis is complex. ⋯ The most commonly used is detection by immunomagnetic method. Although all these methods have limitations, they are helpful for understanding the pathogenesis of CTCs with potential applications in clinical managements in patients with ESCC.