The Diagnostic and Prognostic Value of MiR-92a in Gastric Cancer

Background: miR-92a been proposed to have a signicant role in the diagnosis andprognosis of different types of tumors, but the potential impact of its expression is still controversial due to the sample size. We conducted the meta-analysis to gure out whether miR-92a could be used as a detecting tool and prognosis of gastric cancer. Method: A literature search was performedby retrieving Web ofScience, PubMed, EMBASE, ChineseNational Knowledge Infrastructure (CNKI), VIP(Technology of Chongqing databases) and Wanfang databases (last update by February2020). The sensitivity (SEN), specicity (SPE), positive and negative likelihood ratios (PLR and NLR), diagnostic odds ratio (DOR), and area under the ROC curve (AUC) were pooled to explore the diagnostic performance of miR-92a.The pooled HRs and 95%CIs of miR-92a for overall survival (OS) were calculated to explore the prognostic performance of miR-92a. Subgroup and meta-analysis were further carried out to explore the heterogeneity. Results: 10 articles with12 studies were included. The pooled SEN and SPE were 0.76 (95% CI 0.64–0.85) and 0.79 (95% CI 0.63–0.90).Besides, the pooled PLR and NLR were3.7(95% CI 1.8–7.5)and 0.30 (95% CI 0.18–0.50), and the pooled DOR was 12(95% CI4–38). AUC was 0.84 (95% CI: 0.81–0.87), indicating asignicant value of miR-92a in the gastric cancer detection. For the prognostic analysis of miR-92a in gastric cancer, the univariate and multivariate data’s poor OS were 1.46(95% CI0.87-2.45) and 1.46(95% CI0.90-2.39). Conclusions: The present meta-analysis demonstrated that miR-92a could be a potential biomarker for thedetection of gastric cancer.Furthermore,high expression of studied; (2)number of patients and controls;(3)assay type for evaluating miR-92a; (4)stage of gastric cancer; (5)diagnostic results of SEN, SPE, TP, FP, FN, and TN. For the prognostic value of miR-92a, the following data were extracted: (1)rst author’s name, country, year of publication, ethnicity of the population studied; (2)number of patients and controls;(3)assay type for evaluating miR-92a; (4)stage of gastric cancer; (5) prognostic outcomes including HRs of elevated miR-92a expression for OS/DFS.

cancers, including gastric cancer. Besides, miR-92a has been reported to be an important diagnostic and prognostic tool of other cancers, such as colorectal cancer [6], non-small cell lung cancer [7], breast cancer [8]etc. However, the particular clinical and prognostic roles of miR-92a in tumors still need to be identi ed more precisely.

Search strategy
To identify the relevant studies, we searched databases PubMed, Web of Science, Embase, Chinese National Knowledge Infrastructure (CNKI), Technology of Chongqing(VIP) and Wan Fang databases (up to 10 Feb 2020).In each database, the keywords 'miRNA-92'or 'MicroRNA-92' or ' miR-92' or ' hsa-mir-92' or 'microRNA-92' were used as search terms together 'gastric cancer' or 'stomach neoplasm' or 'stomach cancer' or 'stomach carcinoma' or 'Stomach Neoplasms (Mesh)'. In addition, we also sifted through the reference lists of original articles and manually searched from relevant reviews for additional literatures.

Inclusion and exclusion criteria
In order to screen out eligible studies, speci c criteria were used: (1) gastric cancer was diagnosed via histopathology; (2) the study evaluated the diagnostic or prognostic value of miR-92a in gastric cancer; (3) su cient data were provided to calculate the sensitivity and speci city(for diagnostic value)su cient data were provided to calculate the HR and corresponding 95% CI(for prognostic value).
Exclusion criteria were as follows: laboratory studies, review articles, case reports, animal studies, or studies that did not provide su cient data to calculate the diagnostic or prognostic value of miR-92a. If the same patient population was reported in several publications, the most recent study was selected for analysis.

Data Extraction
Two independent researchers extracted data from all the included studies (GHX and LYT), the uncertain results were assessed by another investigator (WYH). For the diagnostic value of miR-92a, the following data were extracted: (1) rst author's name, country, year of publication, ethnicity of the population studied; (2)number of patients and controls;(3)assay type for evaluating miR-92a; (4)stage of gastric cancer; (5)diagnostic results of SEN, SPE, TP, FP, FN, and TN. For the prognostic value of miR-92a, the following data were extracted: (1) rst author's name, country, year of publication, ethnicity of the population studied; (2)number of patients and controls;(3)assay type for evaluating miR-92a; (4)stage of gastric cancer; (5) prognostic outcomes including HRs of elevated miR-92a expression for OS/DFS.

Quality assessment
For diagnostic meta-analysis, we use QUADAS-2 as a tool to assess the quality of diagnostic value [9]. This tool includes four domains to evaluate: patient selection, index test, reference standard, and ow and timing through the study and timing of the index test and reference standard. The methodological quality graph and methodological quality summary were conducted by Review Manager (version 5.2. Copenhagen: The Nordic Cochrane Centre, the Cochrane Collaboration, 2012). (Fig. 2) For prognostic meta-analysis, the quality of involved studies were evaluated with the Newcastle-Ottawa Scale (NOS) [10,11].In addition, it can evaluate the quality of experiment by answering 8 questions. Each answer ranged score from 0 to 9. Two independent researcher extracted the data and assessed whether each included literature met the quality standards separately (GHX and LYT).

Statistical analysis
For diagnostic accuracy studies, the summary diagnostic index, including SEN and SPE, PLR, NLR, DOR with the corresponding 95% CIs, were calculated. Heterogeneity between studies was determined using Cochran's Q value and I 2 statistics. I 2 values < 25%, 25%-50%, and > 50% were set to indicate mild, moderate, and signi cant heterogeneity. If I 2 > 50%, the random-effects model would be adopted.
Otherwise, a xed-effect model would be utilized for further analysis [12]. The summary receiver operating characteristic (SROC) curve was applied to assess the overall diagnostic accuracy, and the area under the SROC curve (AUC) were constructed for the diagnostic usefulness. Subgroup analysis was carried out by dividing the studies according to different by sample size, assay type and sample type.
For the prognostic meta-analyses, the pooled hazard ratio (HR) and its 95% CI were calculated to elucidate the link between high expression of miR-92a and corresponding OS of gastric cancer patients.
Similarly, Cochran's Q test and I 2 statistics were applied to evaluate the heterogeneity of the pooled results [13]. All statistical analysis was performed by using Stata SE12.0 (StataCorp, College Station, TX) and RevMan5.3 software.
Characteristics and Quality assessment. For the diagnostic analysis, we included 8 studies of 498 cases and 819 controls (Table 1). Besides, the studies are divided by the amount of sample size. Gastric cancer was diagnosed using serum and plasma samples. In addition, all included studies detected miR-92a expression through qRT-PCR using different assay type (Taqman or SYBR). The quality of the included studies, evaluated by the QUADAS-2 assessment tool, is shown in Fig. 2a and 2b, which are suitable for quantitative synthesis. In 4 eligible studies for prognostic studies, 688 participants were included in the univariate analysis and 608 were included in the multivarite( Table 2).All studies were identi ed for assessing for OS.NOS are used for evaluating the detailed quality of these studies( Table 3).The NOS score range from 0 to 8.  1.Representativeness of the exposed cohort; 2. Selection of the non exposed cohort; 3. Ascertainment of exposure;4.Demonstration that outcome of interest was not present at start of study; 5. Comparability of cohorts on the basis of the design or analysis; 6. Assessment of outcome; 7. Was follow-up long enough for outcomes to occur; 8. Adequacy of follow up of cohorts.

Diagnosis meta-analysis
Diagnostic Value of miR-92a in Gastric cancer The summary results of the diagnostic indexes for miR-92a in gastric cancer are presented in Fig. 3 (Fig. 4). The results had signi cant heterogeneity (P < 0 01).
Gastric Cancer In order to annalyze the heterogeneity between studies, a subgroup was performed according to assay type, type of the sample and sample size. As the results shown in Table 4, there aren't any signi cantly differences in the the summary of sensitivity and speci city according to assay type, type of the sample and sample size. Prognosis meta-analysis Prognostic Value of miR-92a in Gastric cancer The univariate (I 2 = 91.6%) and multivariate data (I 2 = 86.4%) were analyzed separately using the Random effect model due to high heterogeneity in the data.
The 4 studies included for univariate analysis showed that there was not signi cant correction between over-expression of miRNA-92a and poor OS (HR 1.46 95% CI 0.87-2.45) (Fig. 5). The 3 studies included for multivariate analysis showed there is not signi cant association between high expression of miR-92a and OS (HR 1.46 95% CI 0.90-2.39) (Fig. 6).
Sensitivity Analysis of the Prognostic Value of miR-92a Expression in Gastric Cancer In univariate analysis, Only one study [21] used the blood sample to investigate the association of miR-92a with OS. This study was omitted, and we found that the result remained similar to the overall results (HR 1.456 95%CI 0.620-3.416). In multivariate analysis, the study [21] that is still only one used palsma was excluded found that sensitivity result was in line with the overall results(HR 1.735 95% 0.54-5.63).

Discussion
Currently, qualifying the up and down-regulated of miRNAs for the assessment of gastric precancerous lesions, have also been proposed but not implemented routinely. Studies have evaluated the diagnostic and prognostic value of miRNAs in human gastric cancer with the method of meta-analysis or in systematic reviews [24].Several miRNAs, such as miR-21, miR-17-5p, etc, which have been proved to be potential biomarks for gastric cancers.With the method of meta-analysis, we evaluate the diagnostic and prognostic value of miR-92a in gastric cancer at present study.The results of the study showed that different assay type, type of the sample and sample size did not have a signi cant effect on the overall diaganostic accuracy. Besides, more moderate speci city and sensitivity in the diagnosis of gastic cancer have been found.And we expand the number of articles for diagnostic value compared with Wei H et al and Liu H et al's studies [24,25]. In the pronostic value, patiens who are with high expression of miR-92a have more longer OS compared with low expression.On a par with Ren C et al's study [26], which only included two studies that investigated the prognostic value of miR-92a in gastric cancer, the present study included more articles, thus could greatly enhance the reliability of the results.
The signi cant role of miR-92a has been found in several cancers, one study indicated that overexpression of miR-92a is associated with osteosarcoma, colorectal cancer, non-small cell lung cancer or hepatocellular carcinoma [27].However, in gastric cancer, few schloars still have de nite statements on the speci c role of miR-92a desperately. Liu H [24]et al's study combined multi-miRNAs showed that the expression of miR-92a was increased inthe serum sample of gastric cancer. Patients with high miR-92a expression have a short survival time [27].But in opposite, one study [28] indicated that levels of miR-92a may be not related to gastric cancer, which found that contrasting results.Recently, Hideyuki Ohzawa et al [29] and Soeda N [30] et al's studies provide a new method for the prediction of gastric cancer, which regard the exosome miR-92a as a biomraker for the diagnosis tool of gastric cancer.And they revealed the same results that gastric cancer patients with high expression of miR-92a and shorter overall survival time. Collectively, these con icting results indicate the need for further studies on the role of miR-92a.
The diagmostic value of miR-92a has been demenstrated in several studies. With a sensitivity and speci city of 76% and 75%, Peng Q et al [31]found that vary expression between the patients with colorectal cancer and healthy controls.Moreover, their experiment indicated that the miR-92a-related combination markers achieved a higher level of diagnostic power.miR-92a also presented high accuracy of diagnosis for cervical cancer, with the sensitivity and speci city were 70% and 80%, respectively [32].For gastric cancer, the diagnostic accuracy of miR-92a varied signi cantly,with a sensitivity ranging from 39.3-97.5% and a speci city ranging from 70.8-97.8%.In addition, there are differences among these studies, such as assay type for qT-PCR, type of the sample and sample size.We found that miR-92a's high accuray of diganosis regardless of these differences.The results indicates that miR-92a can be used as a diagnostic indicator for gastric cancer.
For prognostic value of miR-92a, we founded that high expression of miR-92a may not be associated with poor clinical outcomes of gastric cancer patients, which was 1.46-fold higher risk for poor OS in both univariate and multivariate studies.However, untill we have nished extracting the articles, we have not found any the data of DFS(Disease free survival) and PFS(Progression-free survival) for miR-92a in gastric cancer. Currently, non-invasive biomarkers are more and more popular for assessing survival prognosis at any time before or after treatment.In our study, we have not obvious prognostic effect on gastric cancer, which is inconsistent with previous results of some previous prognostic studies, while our study may is the rst one to report there is a negative association between high expression of miR-92a and patient survival.However, our sample size are larger than previous meta-analysis.In order to clarify the reults, more researches with su cient data need to be done in the future.

Limitations
This study also has several limitations.(1) The sample size was still relatively small, in-cluding only 12 studies.Therefore, more well-designed studies for diagnostic and prognostic value of miR-92a are needed to obtain more reliable results. (2) The different ethnicities varied in the patients with gastric cancer. For example, the diagnostic meta-analysis and the prognostic meta-analysis only focused on Asians. Therefore, more researchers should pay attention to the impact of racial factors in the subsequent studies. (3) We only included articles published in English and Chinese, but did not cover articles in other languages.(4) some risk factors for the development and progression of gastric cancer need to be considered,such as Helicobacter pylori infection, unhealthy diet and etc, which will in uence the reliablity of the study. (5) We only included articles published in English and Chinese, but did not cover articles in other languages. (6) The detection of miR-92a is based on qT-PCR, which having used the different type of assays that will affect the results of the study. Future studies should address these limitations to accurately validate the diagnostic and prognostic value of miR-92a in gastric cancer.

Conclusion
To sum up, we demenstrated for the rst time that miR-92a is promising to be a novel indicator for diagnosis of gastric cancer.But for the prognostic value of miR-92a, it may be not a signi cant biomarker for gastric cancer. Together, these ndings pro-vide important evidence for further development of future non-invasive methods for diagnosing gastric cancer.      SROC curve plotted graph for the diagnostic value of miR-92a in gastric cancer.

Figure 5
Forest plots of the studies that evaluated the hazard ratios of high miR-92a expression on univariate study Figure 6 Forest plots of the studies that evaluated the hazard ratios of high miR-155 expression on multivariate study