Multinomial-sampling models for random genetic drift

OBJECTIVE: The aim of this study was to determine the usefulness of endosonography for evaluating the effect of neoadjuvant therapy for advanced esophageal carcinoma. MATERIALS AND METHODS: Thirty-four patients with esophageal carcinoma (stage II, 16 patients; stage III, 18 patients) underwent various preoperative treatment. In all patients, endosonography was performed before and after treatment, and the percentage reduction in tumor size was calculated from the maximum area of the tumor. In the 27 patients who underwent surgery, the percentage reduction was compared with the pathologic response. Also, the overall survival rates were compared with the percentage reduction in tumor area. RESULTS: Reduction in tumor area ranged from 0% to 47%. The patients were divided into three groups according to the percentage reduction in tumor area. Pathologic response was graded according to the number of viable cells in the entire lesion. Correlation between pathologic response and percentage reduction in tumor area was strong. We found a significant difference in survival rates among the three groups. CONCLUSION: The percentage reduction in tumor area estimated by means of endosonography reflects the histologic effectiveness of neoadjuvant therapy in patients with advanced esophageal carcinoma and may enable clinicians to predict the prognosis of the disease.