Digestive system tumors, including esophageal cancer, gastric cancer, and colorectal cancer, are among the most common cancer types in the world and are the cause of much cancer-related mortality in the world. They are a major threat to human health and are usually diagnosed at an advanced stage. A large number of studies have investigated the use of traditional Chinese medicine (TCM) as an adjuvant therapy in the treatment of digestive system tumors. This TCM has been suggested to possess great advantages in terms of suppressing tumor progression, increasing the sensitivity of chemo-, radio-, or targeted therapeutics, improving an organism's immune system function, and lessening the damage caused by these therapeutics.

In recent years, anti-tumor preparation of TCM has become a hot spot in the research and development of new drugs. Before components and compounds derived from TCM can enter clinical trials of new drugs, there must be research into their pharmacodynamics and safety and evidence to support their preclinical effectiveness. In order to improve the medicinal properties of these TCM drugs, it is urgent to strengthen research on the correlation between their antitumor activity and cytotoxic effect in the digestive system. There also needs to be research directed towards new drug delivery technologies, methods, and advantages of improving oral absorption, changing distribution in vivo, and increasing targeting and improving percutaneous and mucosal absorption of TCM active ingredients. Intestinal flora is a complex microecosystem in the human body, known as the second genome of the human body. TCM can play an anti-tumor role by regulating intestinal flora in coordination with anti-cancer drugs, increasing body immunity, inhibiting the expression of inflammatory factors, and promoting the activity of probiotics.

The aim of this Special Issue is to collect original and review articles on basic and clinical research discussing TCM and natural products for gastrointestinal tract cancer prevention and therapy. We especially welcome applications of TCM and natural products in enhancing chemotherapy and immunotherapy.

Potential topics include but are not limited to the following:

• Isolation and characterization of natural products with anti-digestive system tumor activity
• Chemical properties, structure identification, and synthetic routes of natural and herbal extracts
• Toxicological effects of natural and herbal extracts with anti-digestive system tumor activity
• Biological and pharmacological activities of natural and herbal extracts in the prevention and treatment of digestive system tumors.
• Research on the medicinal properties of natural and herbal extracts, including efficacy, safety, pharmacokinetics, absorption, distribution, and excretion pathways in vivo
• Synergistic effect of drugs and natural products on digestive system tumors
• Preclinical and clinical trials of natural and herbal extracts for the treatment of digestive system tumors
• Bioinformatics analysis of natural and herbal extracts for the treatment of digestive system tumors
• The effect of intestinal flora on tumors and the regulating effect of Chinese medicine on intestinal flora
• Effects of intestinal flora on tumor immunity and the effects of the intervention of TCM