2.1 protocol
The systematic review was conducted following the Cochrane Handbook, the drafting of the manuscript following the indications of the PRISMA (23). the review protocol was previously registered on INPLASY (International Platform of Registered Systematic Review and Meta-analysis Protocols), with registration number: INPLASY202240150 and number DOI is 10.37766/inplasy2022.4.0150.
2.2. Eligibility criteria
The search for sources was directed towards all randomized control trials, prospective non-randomized studies and retrospective studies that investigated the role of miR-195 in HNSCC, with a clear reference to prognostic survival indices in correlation with expression. of miR-195, in particular the HR and RR values between high and low miR-195 expression had to be indicated.
The PICO question formulated was the following: What is the RR and HR in the prognostic indices of survival among HNSCC patients with high tissue miR-195 expression compared to those with low expression? The different points studied were: (P) participants (patients with HNSCC), (I) intervention (impaired expression of miR-195in HNSCC), (C) control (patients with HNSCC who have low expression of miR-195), (O) outcome (difference in death risk of survival prognosis between patients with low and high miR-195 expression in HNSCC).
The exclusion criteria provide for the exclusion of all studies: not written in English; who did not report the HR or the RR or which alternatively did not clearly report the number of HNSCC with high and low expression with the number of deaths at the end of the follow-up period (for the calculation of the RR); High risk or bias; Literature reviews (considered only as sources of information and bibliographic references); case series and case reports.
Therefore, it was decided to include those studies, which having investigated miR-195 in relation to HNSCC, which have the value of RR or HR or which can be calculated with statistical methods, in relation to HR, prognostic survival indices were taken into consideration such as overall survival (OS), diseases free survival (DFS), recurrence free survival (RFS), progression free survival (PFS) and cancer specific survival (CSS), which reported the numerical value (HR), or the Cox regression, or the Kaplan Meier survival curves.
2.3. Sources of information, research and selection.
The research of the studies involved 2 independent reviewers (M.D. and D.S.). The research and selection phase of the articles was carried out in 3 phases, in the first phase the inclusion and exclusion criteria, the databases, the keywords to be used and the period of time in which to conduct the search were jointly decided. second phase we proceeded separately to the research and selection of the studies with the removal of the overlaps using reference management software such as EndNote 8.0 with the inclusion of the studies, in the third phase we proceeded to compare the included studies and to resolve any conflicts between the 2 reviewers with the help, if necessary, of a 3 reviewer (G.T) to decide on doubtful situations.
The keywords used were miR-195 AND HNSCC, Microrna AND HNSCC, LSCC AND miR-195, OSCC AND miR-195, OPSCC AND miR-195, HSCC AND miR-195.
The research was conducted on 2 databases: SCOPUS and PuBMed, and a registry: Cochrane central Trial; In addition, Google scolar (keywords miR-195), gray literature sources such as Open Gray (keywords miR) and the bibbliographic references of previous systematic reviews on miR and HNSCC were consulted,
Specifically below are all the keywords used on pub med: ((((((((((("opscc"[All Fields] OR "opsccs"[All Fields]) AND "miR-195"[All Fields]) OR "HSCC"[All Fields]) AND "miR-195"[All Fields]) OR "LSCC"[All Fields]) AND "miR-195"[All Fields]) OR "OSCC"[All Fields]) AND "miR-195"[All Fields]) OR "miR-195"[All Fields]) AND ("hnsccs"[All Fields] OR "squamous cell carcinoma of head and neck"[MeSH Terms] OR ("squamous"[All Fields] AND "cell"[All Fields] AND "carcinoma"[All Fields] AND "head"[All Fields] AND "neck"[All Fields]) OR "squamous cell carcinoma of head and neck"[All Fields] OR "hnscc"[All Fields])) OR ("microrna s"[All Fields] OR "micrornas"[MeSH Terms] OR "micrornas"[All Fields] OR "microrna"[All Fields])) AND ("hnsccs"[All Fields] OR "squamous cell carcinoma of head and neck"[MeSH Terms] OR ("squamous"[All Fields] AND "cell"[All Fields] AND "carcinoma"[All Fields] AND "head"[All Fields] AND "neck"[All Fields]) OR "squamous cell carcinoma of head and neck"[All Fields] OR "hnscc"[All Fields]); Translations OPSCC: "opscc"[All Fields] OR "opsccs"[All Fields];HNSCC: "hnsccs"[All Fields] OR "squamous cell carcinoma of head and neck"[MeSH Terms] OR ("squamous"[All Fields] AND "cell"[All Fields] AND "carcinoma"[All Fields] AND "head"[All Fields] AND "neck"[All Fields]) OR "squamous cell carcinoma of head and neck"[All Fields] OR "hnscc"[All Fields]; Microrna: "microrna's"[All Fields] OR "micrornas"[MeSH Terms] OR "micrornas"[All Fields] OR "microrna"[All Fields]; HNSCC: "hnsccs"[All Fields] OR "squamous cell carcinoma of head and neck"[MeSH Terms] OR ("squamous"[All Fields] AND "cell"[All Fields] AND "carcinoma"[All Fields] AND "head"[All Fields] AND "neck"[All Fields]) OR "squamous cell carcinoma of head and neck"[All Fields] OR "hnscc"[All Fields].
The record search was completed on March 31, 2022, and a final update on the search was done on April 5, 2022.
2.4. Data collection process, Data characteristics.
The data extraction process was performed by the 2 reviewers after the article inclusion phase and reported on 2 tables to be compared, the type of data to be extracted was agreed in advance before the article selection phase and relate to the first. author the date of publication, the country where the study was conducted, the type of study, the follow-up period, the type of HNSCC, any other targets investigated the cutt-off value between low and high miR-195 expression on number of deaths had for the 2 groups, the number of patients, the RR value, the HR value between high and low expression if present for the various prognostic survival indices.
The possibility of extracting the HR values between high and low expression if the Kaplan Meier survival curves were present was also evaluated, following the method of Tierney et al. (24).
2.5. Risk of bias in individual studies, summary measures, summary of results, risk of bias between studies, additional measures.
The risk of bias in the individual studies was assessed by an Author (MD), as a tool for the evaluation parameters derived from the Reporting Recommendations for prognostic studies of markers (REMARK)(25). Studies with a high risk of bias were excluded from the meta-analysis. The risk of bias between the studies, on the other hand, was assessed through the heterogeneity indices (Higgins index I2) and graphically through the visual analysis of the overlapping of the confidence intervals in the various forest plots and through the funnel Plot, the asymmetry of the funnel plot will be used for a publication bias assessment. The possibility of carrying out a sensitivity analysis was also evaluated in order to identify and exclude the source of heterogeneity; Furthermore, the TSA was performed for the evaluation of the statistical power of the meta-analysis and the GRADE for the quality of the evidence.
For the meta-analysis, Reviewer Manager 5.4 software (Copenhagen Trial Unit, Center for Clinical Intervention Research, Copenhagen, Denmark) was used. the online software GRADE pro-Guideline Development Tool (GRADEpro GDT, Evidence Prime, Hamilton, ON) was used to evaluate the quality of the evidence. the TSA was performed using a Java-based software, the TSA software (Copenhagen Trial Unit, Center for Clinical Intervention Research, Copenhagen, Denmark)(26).