NCIt related terms : Stage I Esophageal Squamous Cell Cancer;
NCIt definition : Stage I includes: T1, N0-1, M0. T1: Tumor invades the lamina propria, muscularis mucosae,
or submucosa. N0: No regional lymph node metastasis. N1: Tumor with metastasis in
one or two regional lymph nodes. M0: No distant metastasis. (AJCC 8th ed.);