| [ Summary ] |
To ascertain the natural course of tumor growth, evaluations were performed prospectively or retrospectively in patients who had not undergone active treatment. Based on many reports on superficial tumors, the initial shape of the common esophageal squamous cancer is thought to be type 0-IIb, a completely flat lesion, the intraepithelial state of which should continue for a relatively long period. After tumor invasion to the lamina propria mucosae, the configuration and growth rate of the tumor may be regulated by the malignant character per se and defense mechanism of each individual, and sometimes by physical and chemical irritating factors. However, many questions, eg. sequence from dysplasia to cancer, in situ to invasive cancer and so on, are still unresolved from the aspect of morphological studies alone. Advances in gene analysis research are anticipated. |