Stage I Ampulla of Vater Neuroendocrine Tumor AJCC v9

**Semantic type:** Neoplastic Process

**Definition:** Stage I includes: T1, NX, N0, M0. T1: Tumor equal to or less than 1 cm in greatest dimension and is confined within the sphincter of Oddi. NX: Regional lymph nodes cannot be assessed. N0: No tumor involvement of regional lymph node(s). M0: No distant metastasis. (AJCC 9th ed.)