PG I and PG II are two important biomarkers that are widely used in clinical settings to diagnose and monitor various gastrointestinal diseases. PG I, also known as pepsinogen I, is mainly secreted by the gastric chief cells and is an indicator of the overall gastric secretory function. On the other hand, PG II, or pepsinogen II, is secreted by both the chief and pyloric cells and is primarily used to assess the risk of gastric cancer.

In 2020, there were about 1.1 million new cases of gastric cancer worldwide, ranking at fourth among the causes of deaths of malignant tumors, and about 800,000 deaths because of the gastric cancer yearly. Asia (mainly China) has the highest number of registered gastric cancer cases (approximately 820,000 new cases and 580,00 deaths), with less than 20% survival rate in 5-yearan as estimated.

Tumor markers are specific substances that can reflect the occurrence and development of tumors and tumor marker level helps to monitor patient’s response to treatment.Tumor markers are present in the tissues, body fluids and excreta of tumor patients, and can be detected by immunological, biological and chemical methods.