Diagnostic and prognostic values of anti‐helicobacter pylori antibody combined with serum CA724, CA19‐9, and CEA for young patients with early gastric cancer

Abstract Background To investigate the value of anti‐helicobacter pylori (Hp) antibody, serum carbohydrate antigen (CA)‐724, CA19‐9, and carcinoembryonic antigen (CEA) in the diagnosis and prognosis evaluation of young patients with early gastric cancer. Methods A total of 200 young patients with gastric cancer from April 2014 to December 2015 were enrolled. A total of 206 patients with gastritis and 204 healthy subjects were also selected. Gastric cancer patients were followed up for 3 years, and the number of recurrences, metastasis, and death was recorded. Results The positive rate of anti‐Hp antibody, CA724, CA19‐9, and CEA in young patients with early gastric cancer were significantly higher than those in gastritis and healthy subjects (P < .05), and was positively correlated with tumor stage, tumor size, and lymph node metastasis (P < .05). The predicting model was as follows: Logit (P) = 26.433‐3.014(CA724)‐3.908(CA19‐9)‐0.303(CEA)‐2.208(anti‐Hp antibody, Positive = 1; Negative = 0). This model had a high value in identifying young patients with early gastric cancer with AUC of 0.918, and the estimated probability was .806. Compared to patients with negative anti‐Hp antibody and low serum levels of CA724, CA19‐9, and CEA, the recurrence rate, metastasis rate, and mortality of patients with positive anti‐Hp antibody, high serum levels of CA724, CA19‐9, and CEA increased significantly (P < .05). Conclusion This study indicated that anti‐Hp antibody combined with CA724, CA19‐9, and CEA had important value in the identification of young patients with early gastric cancer and were of great value in evaluating the risk of postoperative recurrence, metastasis, and death.

rate for men and women is about 2:1, and the mortality rate is the third-highest of all malignant tumors. 3 Although the incidence and mortality have been declining worldwide in recent years, the incidence in young population has not decreased yet. A recent study pointed out that the incidence of gastric cancer in young white people aged 25-39 increased from 0.27/100 000 people in 2002 to 0.45/100 000 people in 2006, and the incidence increased by nearly 100%. 4 The diagnosis of gastric cancer is not difficult, but the onset of gastric cancer is insidious. Most patients with early gastric cancer have no obvious symptom. Some patients have symptoms of nausea, vomiting, or similar upper gastrointestinal tract, which cannot be paid attention to. Therefore, the diagnosis rate of early gastric cancer is relatively low. With disease development, patient has obvious symptoms of upper gastrointestinal discomfort, such as abdominal pain, loss of appetite, weight loss, fatigue, nausea, vomiting, and suffocation. However, most patients had been in advanced stage when the above symptoms occurred. At this stage, the prognosis is poor because of the difficulty of treatment.
Patient's age of gastric cancer onset in China is mainly concentrated in middle-aged and older people (ages older than 40 years). 5 Although the incidence of gastric cancer is low in young people (age is equal to or less than 40 years old), it is gradually increasing in recent years because of the effects of industrialization, environmental pollution, and bad living habits (smoking, drinking, grilling or pickled foods, and irregular schedules, etc). 6 A large number of clinical data and references showed that young gastric cancer had more specific clinical manifestations than middle-aged gastric cancer, with a higher degree of malignancy, earlier metastasis, and poorer prognosis. 7,8 Studies had shown that the 5-year survival rate of early gastric cancer surgery could reach more than 90%, while the 5-year survival rate of postoperative gastric cancer is only 5%-15%. 9 In this case, it is worthwhile to improve the early diagnostic methods for young patients with early gastric cancer.
Anti-helicobacter pylori (Hp) antibody, carbohydrate antigen (CA)-724, CA19-9, and carcinoembryonic antigen (CEA) are all markers for early gastric cancer screening. 8,10-13 However, the relationship between their levels and the clinicopathological features of young patients with early gastric cancer, and the evaluation of postoperative recurrence, metastasis, and death have not been reported. This article selected healthy controls, patients with gastritis, and young patients with early gastric cancer, to explore the diagnostic and prognostic values of anti-Hp antibody, CA724, CA19-9, and CEA in young patients with early gastric cancer. The patients were 23-40 years old, and the average age was 32.17 ± 3.84 years. There were 122 males and 78 females. All patients were stage I-II and were initially diagnosed. All patients were treated with chemoradiotherapy and excluded from other malignancies. Among them, there were 86 cases with tumor diameter ≥3 cm and 114 cases with <3 cm. The staging of all patients was based on a system developed by the American Cancer Association. A total of 206 patients with gastritis were also enrolled. The patients were 21-39 years old, and the average age was 31.87 ± 4.02 years. There were 124 males and 82 females. There was no significant difference in age and gender among the three groups (P > .05), indicating they were comparable.

| Follow-up of young patients with early gastric cancer
According to the time of patients included in the study, they were followed up for 36 months. The number of death and the corresponding death time during the follow-up period were recorded.
The follow-up endpoint was defined as (a) death within 36 months; (b) withdrawal of the study within 36 months; and (c) follow-up up to 36 months.

| Observation and comparison indicators
The subjects fasted for more than 10 hours, and then, 10 mL of venous blood was taken by a professional medical staff using a blood vessel containing a coagulant. In addition, the patient's postoperative peripheral blood was also collected to assess the prognosis.
Blood samples were centrifuged at 3600 g for 15 minutes at 4°C for 1 hour, and the upper serum was collected. CA724, CA19-9, and CEA were detected by chemiluminescence immunoassay. The test instrument is the ARCHITECT i2000sr automatic immunoassay analyzer (Abbott Company), and the kit is the original imported test for it. The carbon-13 ( 13 C) urea breath test qualitatively determined the anti-Hp antibody level. The subjects fasted for 12 hours. First, inject the first balloon and then take the 13 C urea 1 capsule. After 30 minutes, the second balloon was blown out and tested. Experimental standard: super standard ≤4 is negative and >4 is positive.

| Establishment of the logistic regression model
A logistic regression model for young patients with early gastric cancer was established. The formula is Logit (P) = β 0 + β 1 X 1 +β 2 X 2 +… +β n X n = ln[P/(1-P)], "P" means the probability of young patients with early gastric cancer, "β" means the coefficient of each parameter, and "X" means the value of each parameter.

| Statistical analysis
All analyses were performed using SPSS 21.0 software. The measurement data were expressed as mean ± standard deviation (SD). Variance analysis and t test were used for comparison between multiple groups and two groups. The rate was compared using a chi-square test. The Spearman method was used to analyze the correlation between each indicator and clinical features. The receiver operating characteristic curve (ROC) was used to analyze the diagnostic value of anti-Hp antibody, CA724, CA19-9, and CEA for young patients with gastric cancer.
Survival curve analysis was performed using the Kaplan-Meier method, and statistical difference between survival curves was calculated by log-rank test. Logistic regression was used to calculate the odds ratio (OR) and 95% confidence interval (CI) for anti-Hp antibody, CA724, CA19-9, and CEA in predicting young patients with gastric cancer. The test level is α = .05.

| Comparison of anti-Hp antibody positive rate, CA724, CA19-9, and CEA levels among three groups
The differences in anti-Hp antibody positive rate and CA724, CA19-9, and CEA levels among young patients with early gastric cancer and gastritis and healthy subjects were statistically significant (P < .05). The positive rate of anti-Hp antibody and the serum levels of CA724, CA19-9, and CEA in young patients with early gastric cancer were significantly higher than those in gastritis patients and healthy subjects (P < .05). Besides, the positive rate of anti-Hp antibody in patients with gastritis was significantly higher than that in healthy subjects (P < .05), as shown in Table 1.  Tables 2 and 3, and Table S1).

| Correlation between anti-
However, they did have significant positive correlations with tumor stage, tumor size, and lymph node metastasis (P < .05, Tables 2 and   3, and Table S1). Anti-Hp antibody positive rate and serum CA724, CA19-9, and CEA levels were all significantly increased in patients with tumors in stage II or tumor diameter ≥3 cm, and also patients with lymph node metastasis.

| Prognostic value of anti-Hp antibody, CA724, CA19-9, and CEA
Anti-Hp antibody, serum CA724, CA19-9, and CEA levels were detected in postoperative patients. According to the median serum levels of CA724, CA19-9, and CEA (CA724: 1.36 U/mL; CA19-9:24.19 U/mL; CEA: 1.38 ng/mL), patients were divided into the high-and the low-level groups. Compared to patients with negative anti-Hp antibody and low levels of CA724, CA19-9, and CEA, the recurrence rate, metastasis rate, and mortality of patients with positive anti-Hp antibody and high levels of CA724, CA19-9, and CEA increased significantly (P < .05, Table 4 and Figure 2). Cox analysis showed that the positive anti-Hp antibody and high serum levels of CA724, CA19-9, and CEA were all risk factors for postoperative death in young gastric cancer patients (P < .05, Table 5).

| D ISCUSS I ON
In recent years, with the emphasis on gastric cancer and the adjustment of dietary structure, the incidence of this disease has decreased slightly overall, but the new cases have gradually shown a trend of youthfulness, which is a huge threat to human health.
Since gastric cancer in young people has the characteristics of "fast TA B L E 1 Comparison of anti-Hp antibody positive rate, CA724, CA19-9, and CEA levels among three groups    However, this study has the following shortcomings: (a) This study is a retrospective study, the gastric cancer was confirmed before the study conducted, and some patients had already progressed to stage II as we all know that the different stage of the disease re- were from only one hospital, which caused case selection bias and affected the results. That means, our results are still waiting to be confirmed by multicenter cohort study.
In summary, we found that combining the anti-Hp antibody with the serum CA724, CA19-9, and CEA had important values in the identification of young patients with early gastric cancer and was of great value in evaluating the risk of postoperative recurrence, metastasis, and death.

ACK N OWLED G M ENTS
None.

AUTH O R CO NTR I B UTI O N S
HZ researched literature and conceived the study. XG and HZ involved in protocol development, gaining ethical approval, patient recruitment, and data analysis. XG wrote the first draft of the study.
All authors reviewed and edited the study and approved the final version of the study. Abbreviations: CA724, carbohydrate antigen-724; CEA; carcinoembryonic antigen; CA19-9, carbohydrate antigen 19-9.