Abstract: The cure rate of gastric cancer, a highly aggressive digestive tract malignancy, can reach more than 90%, if it can be treated by surgery at the early stage. However, due to the lack of obvious symptoms and sensitive tumor markers in the early stage of gastric cancer, nearly 80% of gastric cancer patients in China are in advanced stage when first diagnosed. As an emerging molecular detection technology, liquid biopsy is noninvasive, quick, economic and reproducible, and has better sensitivity and specificity than serological tumor markers. It can also detect tumor in advance of pathological biopsy, which brings a bright light for early detection and risk assessment of gastric cancer. Yet, liquid biopsy has not been widely used in clinic due to many factors. One of the main reasons is that most samples of traditional liquid biopsies are from patient’s blood (including plasma and serum), and the low concentration of cancer-derived components in the blood samples limits the ability of liquid biopsy to detect and warn occurrence or recurrence of early cancer. Recent research has further expanded the concept of liquid biopsies, finding that biopsies derived from fluids other than blood, called non-blood derived liquid biopsy, can better screen, diagnose and monitor tumors, promising to advance the use of liquid biopsies for the early diagnosis of gastric cancer. Therefore, by searching the relevant literature in recent years, we analyzed the advantages and challenges of non-blood derived liquid biopsy compared with traditional liquid biopsy, and reviewed the research advances of liquid biopsy derived from saliva, gastric juice, gastric wash and urine in gastric cancer.

Key words: Liquid biopsy, Gastric cancer, Early diagnosis, Body fluids