To date, China still has a high mortality rate of GC, which is mainly attributable to delayed diagnosis. In this regard, it is crucial to improve the early detection of the GC. Currently, the most widely accepted risk predictive model for GC in the Chinese population is the Lee's Scale, which is mainly used to predict the risk of GC based on serological indicators in asymptomatic individuals. However, there is no risk predictive model for the endoscopic screening population.
Atrophy, an important stage in the development of the GC, is mainly assessed according to the KTC under the endoscopy. It has been shown that the risk of GC increases with a higher grade of KTC, which can be used to stratify the risk of GC under the endoscopy . Even after H. pylori eradication, the KTC is still an independent risk factor for the development of GC. It has also been documented that the KTC can be used to discriminate the gastric adenoma and early GC. Therefore, the present study explored the relationship between KTC and the risk of GC.
In this work, the results showed that except for the C1 type, all other types increased the risk of GC. Then, we further modified the KTC from a clinical perspective. The boundary between C3 and O1 types is the lesser curvature of the gastric body near the cardia, which is difficult to be recognized in clinical practice, so endoscopists can easily misjudge O1 as C3. Besides, the boundary of the O1 and O2 types is the middle of the gastric fundus. During the endoscopic procedure, the thin mucosa of the gastric fundus is susceptible to hyperinflation, leading to the misjudgments of O1 and O2 types. Therefore, we modified the KTC by combining the C3, O1, and O2 types, which could simplify the clinical practice and increase the accuracy and reliability of the classification. Finally, our results indicated that the modified KTC was associated with the risk of GC, and the risk increased with the higher grade of the modified KTC.
Next, we screened other potential risk factors for GC. Previous studies found that the incidence of GC increased with age progressively and was higher in males. Those with a family history of GC in first-degree relatives had a significantly higher risk of GC. In addition, a cohort study showed that smoking increased the incidence of GC, especially in H. pylori-positive patients.
In this research, the univariate analysis showed that age, sex, smoking, alcohol, and family history of GC were statistically significant, which is consistent with the results of the previous studies above. However, in multivariate analysis, we found that smoking and alcohol were not statistically significant when the variable of sex was included in the regression analysis. The subgroup analysis of sex also showed that there was no statistically significant difference of smoking and alcohol for GC, which might because the proportion of smoking and alcohol was higher in males. In addition, a cohort study of Chinese ethnicity in Singapore showed that only smoking more than 20 packs per year was associated with an increased risk of GC. So, the possible explanation for this discrepancy might lie in the differences in consumption of smoking and alcohol. A further stratified investigation is necessary for understanding the impacts of tobacco and alcohol on GC risk.
A retrospective study showed that bile reflux was associated with GC and the level of bile reflux is positively correlated with the severity of the gastric mucosal lesion. Another study showed that xanthoma was an independent risk factor for GC. But the results of our study indicated that neither bile reflux nor xanthomas were related to GC. Thus, the association of bile reflux and xanthomas with GC maybe controversial. But it has to be mentioned that the bile reflux was not graded in our study and the mutual influence between Hp and bile reflux still lacks co-analysis, which might lead to the discrepancy with the previous study. For gastric xanthomas, it is a relatively rare gastric lesion, some endoscopists may miss the diagnosis because of insufficient understanding of this lesion. Therefore, there was a small number of positive cases in this study which may cause the irrelevance of xanthomas and GC.
Lastly, according to the results of univariate and multivariate analysis, we developed an endoscopic real-time GC risk predictive model based on the KTC, with good discrimination (AUC = 0.781), calibration, and clinical utility. And the nomogram was constructed to present the model. The scores calculated according to the nomogram for all patients further stratified the population into low risk (score 0–69), medium risk (score 70–99), and high risk (score ≥ 100). Referring to the AGA Clinical Practice Update on the Diagnosis and Management of Atrophic Gastritis, and combined with the risk stratification obtained from our study, we established the following clinical management strategies. Firstly, we recommend the biopsy from five points for the high-risk population, and three points for the medium-risk population to further assess the OLGA and operative link for gastric intestinal metaplasia assessment (OLGIM), even if no mucosal lesions are found under the endoscopy. Secondly, the follow-up time can be reduced to 6 months for the high-risk population and 12 months for the medium-risk population. For those in low risk, it can be appropriately extended to 2–3 years. However, reassessment of the risk of GC and adjustment of the strategies after every endoscopy is needed. Moreover, many studies have found that atrophic gastritis can be reversed. For example, a 10-year follow-up in Korea found that H. pylori eradication treatment could reverse atrophic gastritis. A multi-center cohort study in China showed that the lamb's tripe extract and vitamin B12 capsule could reverse both atrophy and intestinal metaplasia. And several studies have shown that Weifuchun (WFC) alone, WFC combined with Rebamipide and WFC combined with Tepronone could improve the pathological grading or clinical outcomes in patients with chronic atrophic gastritis. Therefore, for the medium and high-risk populations, the eradication of H. pylori is strongly recommended. After H. pylori eradication, the drugs mentioned above can be appropriately used to decrease the extent and degree of atrophy and further reduce the risk of GC as much as possible.
Compared with existing models, our model has unique advantages. Firstly, the model can predict GC risk only based on the KTC and patients’ basic characteristics, which is applicable for real-time guidance of biopsy and clinical management under the endoscopy with less burden for clinicians, lower suffering and cost for patients. Secondly, neither serological testing nor pathological examination is needed in the model, which can reduce the influence of other factors and improve the accuracy and reliability of the model. Thirdly, the KTC is widely used in clinical practice and there is an international uniform standard for it, which will make the model widely used. Nonetheless, there are still some deficiencies in this model. Firstly, the data of our study were collected from a single center, and further validation is needed to confirm its generalization. Secondly, only inpatients were selected and patients for physical examinations were not included, so there might be selection bias in our study. Thirdly, this study retrospectively collected the information of the patients, so the variables that could be collected were limited. In the future, other endoscopic findings such as diffuse redness, regular arrangement of collecting venules (RAC) and endoscopic grading of the gastric intestinal metaplasia (EGGIM) can be combined to improve the efficacy of the model.