Numerous studies have found that, usually, gastric cancer does not develop directly from the normal gastric mucosal epithelium, but evolves gradually over a considerable period of time. The period before the development of significant clinical symptoms is called precancerous changes. According to the clinical situation and pathological histological changes, precancerous changes of gastric cancer are divided into two types: gastric precancerous state and gastric precancerous lesions.
Precancerous state of the stomach
Precancerous state of the stomach refers to a number of clinical conditions or diseases that lead to a significantly increased risk of gastric cancer, mainly including the following.
Chronic atrophic gastritis
Chronic atrophic gastritis is the most common of the precancerous states of the stomach, accounting for more than 2/3 of precancerous states of the stomach. Because the incidence increases with age, it is mainly seen in the middle-aged and elderly population. It is believed that the natural course of gastric cancer development is normal gastric mucosa → chronic superficial gastritis → chronic atrophic gastritis → intestinal epithelial hyperplasia → heterotypic hyperplasia → intestinal gastric cancer. The cancer rate of chronic atrophic gastritis is 8.6% to 13.8% in foreign countries and 1.2% to 7.1% in China.
Gastric polyps
Gastric polyps are more common and can be solitary or multiple. The histologic types are divided into proliferative polyps (also called non-neoplastic polyps) and adenomatous polyps.
Proliferative polyps are more common, mostly less than 1.5 cm in diameter, and are rarely malignant, with a reported malignancy rate of only 1%. The rate of malignant transformation can be as high as 60% when the diameter is not less than 2 cm, especially in the case of choroidal adenoma. Adenomatous polyps are more likely to be intestinal type gastric cancer after malignant transformation.
Clinically, polyps no smaller than 2 cm in diameter, multiple polyps, and broad-based polyps with large bases are considered to have a high rate of malignancy and should be given adequate attention.
Gastric ulcers
Gastric ulcers have much in common with gastric cancer, yet the relationship between the two has been controversial. A national study based on 10,044 patients with gastric ulcers showed that the chance of pathologically determined cancer in ulcers was only 2.1%, and that the cancer occurred more often in the mucosa surrounding the ulcer than from the ulcer itself.
As of today, clinicians and pathologists have not found definitive evidence of ulcers turning into gastric cancer.
Gastric mucosal dysplasia
Gastric mucosa with congenital dysplasia is characterized by atypical and abnormally differentiated cells, poor mucosal architecture, and potential for malignancy. Gastric mucosal dysplasia can be classified as low-grade dysplasia or high-grade dysplasia based on the presence or absence of a history of ulceration. Low-grade dysplasia is stable in nature and has less impact on the body; high-grade dysplasia is more likely to be malignant.
When gastroscopy reveals moderate-to-severe dysplasia, histology should be performed and followed up regularly.
Gastric mucosal giant crepitus
A rare disease in which serum protein is lost through giant gastric mucosal folds, with clinical manifestations of hypoproteinemia and swelling. The cancer rate for this disease is 10% to 13%.
Warty gastritis
The cause of this disease is unknown and is currently thought to be related to H. pylori infection, a metabolic immune response, and high gastric acid secretion. Some studies have shown that warty gastritis is strongly associated with gastric carcinogenesis and should be considered a high-risk precancerous state.
Post-gastrectomy
There is a possibility of residual gastric cancer after surgical resection of benign gastric disease. Foreign studies have found that the rate of postoperative gastric stump carcinoma can be as high as 5% to 16%; the incidence of residual gastric cancer reported in China is 2.16% to 2.5%. The incidence of residual gastric cancer appears to be directly related to the postoperative interval, with a few cases occurring within 10 years after surgery and most occurring within 10 to 20 years after surgery, and with a predominantly male population, with some reporting a male to female ratio of up to 36:1. Most studies suggest that postoperative residual gastric cancer has a poor outcome and a low 5-year survival rate.
Gastric precancerous lesions
Gastric precancerous lesions are a pathologic histologic concept, and such changes are more likely to be cancerous than normal tissue or other pathologic changes in the gastric mucosa, including primarily intestinal epithelial metaplasia and atypical hyperplasia.
Intestinal epithelial metaplasia of the gastric mucosa
Refers to the replacement of intrinsic glands of the gastric mucosa by intestinal adenoid glands in pathological situations (i.e., replacement of gastric mucosal epithelial cells by intestinal-type epithelial cells), and the appearance of cupular and absorptive cells that should be present in the intestinal epithelium when stimulated.
Based on the histological changes, intestinal epithelial metaplasia can be divided into 3 subtypes: complete small bowel type (type I), incomplete small bowel type (type II), and incomplete large bowel type. Studies have confirmed that the risk of gastric cancer in incomplete intestinal epithelial hyperplasia is much greater than that in complete intestinal epithelial hyperplasia. The probability that a patient with intestinal epithelial metaplasia will eventually develop gastric cancer is approximately 0.25%.
Atypical hyperplasia
Also known as heterogeneous hyperplasia, it is a type of lesion in which the tissue and cells proliferate abnormally and poorly differentiated, resulting in morphologic and structural changes that are histologically intermediate between benign and malignant. Atypical hyperplasia of the gastric mucosa has a tendency to become malignant.
The timely detection of precancerous states and precancerous lesions in the stomach, enhanced regular review and preventive measures can prevent or detect gastric cancer at an early stage, which is why doctors often ask patients to undergo further investigation or regular review.