Stomach cancer usually begins in the mucus-producing cells that line the stomach. This type of cancer is called adenocarcinoma.
For the past several decades, rates of cancer in the main part of the stomach (stomach body) have been falling worldwide. During the same period, cancer in the area where the top part of the stomach (cardia) meets the lower end of the swallowing tube (esophagus) has become much more common. This area of the stomach is called the gastroesophageal junction.
Stomach cancer care at Mayo Clinic