Overall, there was little change in biliary system tumors of the 5th edition of WHO classification of digestive system tumors after update. The three-tiered classification of biliary intraepithelial neoplasia changed to two-tiered system: high-grade and low-grade, in the section of benign tumors and precancerous lesions. And both intracholecystic and intraductal papillary tumors associated with invasive carcinoma were added. The classification of intrahepatic bile duct tumors introduced parts of bile duct adenoma and bile duct adenofibroma, which were mentioned previously in the differential diagnosis with bile duct carcinoma. Intrahepatic cholangiocarcinoma was divided into small bile duct subtype and large bile duct subtype in the 5th edition of WHO classification, and the names of cholangiocellular carcinoma and cholangiole cell carcinoma were no longer recommended to use. Extrahepatic cholangiocarcinoma was listed as a separate part for the first time, including squamous cell carcinoma, adenosquamous carcinoma and undifferentiated carcinoma in addition to common histological types. Some new contents of molecular pathology in the 5th edition of WHO classification were added, which provided the basis for precise classification and diagnosis of tumors in biliary system.

As the perioperative chemotherapy and conversion therapy has been widely implemented on the standard treatment of gastric cancer patients, it is of great importance to evaluate the efficacy of these patients accurately by effective methods. Being an important grading standard for histomorphological evaluation of excision specimens after neoadjuvant chemotherapy, pathological tumor regression grade (TRG) system is mainly used to assess the degree of fibrosis of tumor tissue and the proportion of residual tumor cells. TRG evaluation may provide important information referring to clinical decision making and prognostic judgment, and may imply on different efficacy and survival rates. Currently, four TRG standards can be used to evaluate the efficacy of neoadjuvant chemotherapy or translational therapy for primary gastric cancer, including Becker, Mandard, Ninomiya and Ryan, among which Ryan's 0-3 classification system is the most widely used. The main factors influencing the outcome of postoperative pathological TRG evaluation of gastric cancer include tumor localization, macroscopic observation and dissection of specimens, microscopic evaluation, as well as TRG evaluation criteria that are too complicated and difficult to operate. Although some studies have found that tumor regression of gastric cancer may be associated with some molecular markers, it may bring greater benefits to the choice of treatment decisions and prognosis judgment if further studies can confirm that specific biomarkers can help estimate the efficacy of neoadjuvant chemotherapy and translational therapy for gastric cancer after endoscopic biopsy.