TABLE 1.
Characteristics of the eligible meta-analyses of multiple risk factors for cervical cancer (Liaoning, China. 2021).
| Risk factor | Individual study | No. of studies | Effect metric | Outcome | Level of comparison | Study design |
|---|---|---|---|---|---|---|
| Life style | ||||||
| Past smokers | (33) | 3 | OR | Adenocarcinoma | Past vs. never smokers | Case control |
| Current smokers | 3 | OR | Current vs. never smokers | |||
| Past smokers | 3 | OR | Squamous cell carcinoma | Past vs. never smokers | ||
| Current smokers | 3 | OR | Current vs. never smokers | |||
| Past smokers | (34) | 10 | RR | Adenocarcinoma | Past vs. never smokers | Case control |
| Current smokers | 10 | RR | Current vs. never smokers | |||
| Overweight | (35) | 9 | OR | Cervical cancer | Overweight vs. reference | Case control, cross sectional, and cohort |
| Obesity | 9 | OR | Obesity vs. reference | |||
| Smoking | (36) | 5 | RR | Cervical cancer | Smokers vs. never smokers | Case control and cohort |
| Virus, microorganism, and parasite | ||||||
| HPV and HPV16 | (37) | 3 | RR | Invasive cervical cancer/Cervical carcinoma in situ | Exposed vs. unexposed | Case control |
| 4 | RR | |||||
| Herpes simplex type 2 | (38) | 16 | OR | Cervical cancer | Exposed vs. unexposed | Nested case control and case control |
| HPV16 A4/Asian variants | (39) | 7 | OR | Invasive cervical cancer | A4 vs. A1-3 variants | Case control |
| Chlamydia trachomatis infection | (40) | 3 | OR | Cervical cancer | Exposed vs. unexposed | Case control, nested case control, cross sectional, and cohort |
| 16 | OR | |||||
| Coinfection of HPV and Chlamydia trachomatis | 6 | OR | ||||
| Chlamydia trachomatis infection | 10 | OR | Squamous carcinoma | |||
| 4 | OR | Adenocarcinoma | ||||
| Chlamydia trachomatis infection (serum) | 15 | OR | Cervical cancer | |||
| Epstein-Barr virus | (41) | 9 | OR | Cervical cancer | Exposed vs. unexposed | Case control |
| Cervicovaginal lactobacilli | (42) | 3 | OR | Cervical cancer | Cervicovaginal lactobacilli vs. non-lactobacilli-predominant CST IV | Cross sectional |
| Reproductive factors | ||||||
| In vitro fertilization | (43) | 4 | RR | Cervical cancer | Exposed vs. unexposed | Cohort |
| Intrauterine device use | (44) | 10 | OR | Cervical cancer | Intrauterine Device Use vs. no use | Friend/Family and cohort |
| Oral contraceptives use | (10) | 4 | OR | Cervical carcinoma in situ | Exposed vs. unexposed | Case control and cohort |
| 4 | OR | Cervical adenocarcinoma | ||||
| 5 | OR | Squamous cell carcinoma | ||||
| Oral contraceptives >10 years | 3 | OR | Cervical cancer | |||
| Diseases | ||||||
| Endometriosis | (45) | 3 | RR | Cervical cancer | Exposed vs. unexposed | Cohort |
| Gestational diabetes mellitus | (46) | 3 | RR | Cervical cancer | Exposed vs. unexposed | Cohort |
| Nutrients and their levels | ||||||
| Total vitamin A intake | (47) | 11 | OR | Cervical cancer | Highest vs. lowest | Case control |
| Blood vitamin A levels (retinol) | 3 | OR | ||||
| Blood vitamin A levels (carotene) | 4 | OR | ||||
| Retinol intake | 8 | OR | ||||
| Carotene intake | 7 | OR | ||||
| Carotenoid intake | 3 | OR | ||||
| Retinol intake | 3 | OR | Early stage cervical cancer | |||
| Carotene intake | 3 | OR | ||||
| Serum selenium levels | (48) | 5 | OR | Cervical cancer | Highest vs. lowest | Case control |
| Vitamin E | (49) | 8 | OR | Cervical cancer | Highest vs. lowest | Case control |
Abbreviation: CI, confidence interval; CST, community state types; HPV, human papillomavirus; HR, Hazard ratio; OR, Odds ratio; RR, Relative risk.
All statistical tests were two-sided.