Chronological Changes in the Gastric Cancer Subsite in Akita, Japan: The Trends from the Data of a Hospital-Based Registration System.

With the decreasing global trend in the Helicobacter pylori infection rate, compositional changes in the gastric cancer subsites have occurred worldwide. However, the compositional changes in Asian countries, including Japan, remain to be clarified. The aim of this study is to investigate the latest chronological changes in the gastric cancer subsite using a hospital-based registration system in Akita prefecture in Japan. From 2007-2015, subsites of gastric cancers were coded according to the International Classification of Diseases for Oncology (ICD-03). The nine-year registration period was divided into the three 3-year periods: 2007-2009, 2010-2012, and 2013-2015. A total of 10,804 cases of gastric cancer were registered. The proportion of cardiac cancer among total gastric cancer slightly but significantly declined from 12.1% in 2007-2009 to 9.2% in 2013-2015 (P < 0.01). Among non-cardia cancer, the proportion of corpus cancer significantly increased from 41.3% to 50.2% during the study period (P < 0.01), while that of antropylorus cancer significantly decreased from 37.6% to 34.3% (P < 0.05). Such compositional changes in the gastric cancer subsite were observed largely in men, regardless of the histologic subtype of cancer. With the decreasing H. pylori infection rate, compositional changes in the gastric cancer subsite are occurring in Japan. While the proportion of cardia and antropylorus cancer is declining, that of corpus cancer is increasing, indicating diverse etiology of gastric carcinogenesis depending on the subsites. Identifying the most common sites of occurrence, may help to improve the efficiency of screening for gastric cancer.