This Research Topic aims to collect all the Case Reports submitted to the Gastrointestinal Cancers sections. All the Case Reports submitted to this collection will be personally assessed by a senior Associate Editor before the beginning of the peer-review process. Please make sure your article adheres to the following guidelines before submitting it.

This Research Topic aims to collect all the Case Reports submitted to the Surgical Oncology section. All the Case Reports submitted to this collection will be personally assessed by a senior Associate Editor before the beginning of the peer-review process. Please make sure your article adheres to the following guidelines before submitting it.

Gastrointestinal (GI) cancers, including gastric cancer, colon cancer, liver cancer, esophageal cancer, and pancreatic cancer, seriously threaten the health of human beings worldwide with a high rate of morbidity and mortality. The clinical successes achieved with immune checkpoint inhibitors (ICIs) targeting PD-1/PD-L1 and CTLA-4 have opened a new cancer therapy era and brought new hope to cancer patients. However, the overall response rate (ORR) of ICI monotherapy in the non-selective population is only about 20%, in which some patients subsequently develop immunotherapy resistance. Moreover, the remaining 70-80% of patients displayed primary resistance to ICIs, and a few patients even experienced hyper progression disease (HPD). Although PD-L1 expression, mismatch repair deficient (MMRd), high tumor mutational burden (TMB-H) , high homologous recombination deficiency (HRD), and tumor infiltrated immune cells (TILs) are known as effective biomarkers for immunotherapy, growing studies have reported that ICIs could not improve the OS of all patients with PD-L1 expression higher than 50%, and the ORR of MSI-H patients was only about 60%, whereas some patients with low PD-L1 expression or MSS could still benefit from immunotherapy, indicating the complexity of ICI resistance. Therefore, it is of great importance and significance to explore the prediction biomarkers for primary or acquired immunotherapy resistance and elucidate their underlying molecular mechanisms and develop reversal strategies. Due to the multiple steps of the cancer immune cycle and complex immune microenvironment, any disorders of immune cell infiltration or T cell activation, such as lack of antigens and/or their presentation, lack of response to antigen presentation, and T cell priming, could contribute to ICI resistance. The combination with anti-angiogenesis therapy, radiotherapy, chemotherapy, and other ICIs has improved the efficacy of ICI therapy to some extent in the clinic. Although numerous studies related to ICI resistance were reported in GI cancers, due to the strong spatial/temporal heterogeneity and the complex immune microenvironment in different kinds of GI cancers and different individuals, many questions about ICI resistance and reversal strategies remain unsolved. The aim of this Research Topic is to provide a forum to exhibit the latest research achievement related to the exploration of biomarkers for immunotherapy resistance including HPD and the underlying molecular mechanisms, as well as the development of reversal strategies in GI cancers. We hope this Research Topic will lead to a better understanding of precision cancer immunotherapy and provide useful clues for clinical application to benefit more GI cancer patients with immunotherapy.

Precision medicine is the main emphasis in healthcare after recognizing the importance to integrate the clinical data with the molecular data of a specific disease. The term was first introduced in 2015 in which the Precision Medicine Initiative was initiated with the final aim to provide targeted therapy with high efficacy and less toxicity. Precision medicine plays an increasingly important in gastrointestinal cancers. Gastrointestinal cancers are divided into the upper (esophagus, stomach) and lower part (hepatobiliary and colon) of the gastrointestinal system. We would like to explore the latest era of integrative therapeutic target in gastrointestinal cancers taking into consideration of various aetiologies including genetic and exposome (dietary factors, microbial, hormonal, environmental insults) and their interactions with the host microenvironment.