Clinicopathologic Implication of New AJCC 8(th) Staging Classification in the Stomach Cancer

Kim, Sung Eun

Abstract

Stomach cancer is the fifth most common malignancy in the world. The incidence of stomach cancer is declining worldwide, however, gastric cancer still remains the third most common cause of cancer death. The tumor, node, and metastasis (TNM) staging system has been frequently used as a method for cancer staging system and the most important reference in cancer treatment. In 2016, the classification of gastric cancer TNM staging was revised in the 8(th) American Joint Committee on Cancer (AJCC) edition. There are several modifications in stomach cancer staging in this edition compared to the 7(th) edition. First, the anatomical boundary between esophagus and stomach has been revised, therefore the definition of stomach cancer and esophageal cancer has refined. Second, N3 is separated into N3a and N3b in pathological classification. Patients with N3a and N3b revealed distinct prognosis in stomach cancer, and these results brought changes in pathological staging. Several large retrospective studies were conducted to compare staging between the 7(th) and 8(th) AJCC editions including prognostic value, stage grouping homogeneity, discriminatory ability, and monotonicity of gradients globally. The main objective of this review is to evaluate the clinical and pathological implications of AJCC 8(th) staging classification in the stomach cancer.