| Study | Selection | Comparability | Outcome | TOTAL | Quality |
|---|
| REC | SNEC | AE | DO | SC | AF | AO | FU | AFU |
|---|
| Ichihara 2020 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 1 | 6 | Moderate |
| Wang 2019 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 1 | 6 | Moderate |
| Popinat 2019 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 | High |
| Naik 2019 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 | High |
| Magri 2019 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 | High |
| Labadie 2019 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 | High |
| Kulkarni 2019 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 6 | Moderate |
| Kichenadasse 2019 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 | High |
| De Giorgi 2019 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 | High |
| Cortellini 2019 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 1 | 6 | Moderate |
| Richtig 2018 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 1 | 6 | Moderate |
| Zhi 2018 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 5 | Moderate |
| McQuade 2018 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 | High |
- REC, representativeness of the exposed cohort; SNEC, selection of the non-exposed cohort; AE, ascertainment of exposure; DO, demonstration that outcome of interest was not present at start of study; SC, study controls for age, sex; AF, study controls for any additional factors (chemoradiotherapy, curative resection); AO, assessment of outcome; FU, follow-up long enough (36 M) for outcomes to occur; AFU, adequacy of follow-up of cohorts. “1” means that the study is satisfied the item and “0” means the opposite situation
