Introduction
Gastric cancer, which has a gradually decreasing incidence in many industrialized countries, still remains the second leading cause of cancer related deaths around the world. (1). Gastric cancer is classified into two main types: intestinal and diffuse. Intestinal type gastric cancer is related to premalignant lesions such as chronic atrophic gastritis (AG) and intestinal metaplasia (IM) (2,3). IM, defined as gastric mucosa changing into epithelium with intestinal morphology, is associated with Helicobacter pylori (H. pylori) infection, and during this infection, gastric mucosa progresses into many stages of chronic gastritis, AG and IM (4,5).
Colorectal cancers (CRC) are one of the most common cancers worldwide. Colorectal carcinogenesis usually originates from colorectal adenomas that develop from normal mucosa and the adenoma – carcinoma sequence (6,7). This process gives us a chance to early diagnose and intervene before the development of cancer. Colorectal adenomas are considered the most important precancerous lesions for CRC. These two diseases, colorectal adenomas and CRC, are collectively referred to as colorectal neoplasia.
Clarifying the pathogenesis and the risk factors of colorectal cancers is of great importance in the early diagnosis and treatment of this cancer (7). Various previous studies were conducted on this matter after H. pylori infection was accepted as a risk factor for colorectal cancer in the 1990s (9). While some studies determined a positive association between H. pylori infection and colorectal cancers (10-15), there were studies stating that this was controversial as well (16-18). In addition, studies investigating the association between gastric IM and colorectal adenomas were also conducted (7,13,19). In a recent study, a significant association between gastric IM and colorectal adenoma prevalence was reported (13). The aim of this study was to evaluate the relationship between H. pylori infection and IM, which is considered a premalignant lesion for gastric cancer, with colon neoplasia.