Table 1. Main characteristics of the included studies involving toothbrushing and the risk of esophageal carcinoma.
| First author [publication year], region | Study design | Sex, age | Participants | Cases | Definition and grouping of exposure | Definition of outcome | Adjustment factors | Lowest vs. highest, OR [95% CI] | Study quality |
|---|---|---|---|---|---|---|---|---|---|
| Wang Y I (11) [1992], Asia | Case-control | M&F, ≥30 | 413 | 210 | Self-reported brushing frequency: 0; ≥1/day | Ascertained from hospital registries (X-ray) | Age, sex and occupation | 0 vs. ≥1, 0.91 [0.56, 1.43] | 6 |
| Wang Y II (11) [1992], Asia | Case-control | M&F, >30 | 305 | 116 | Self-reported brushing frequency: 0; ≥1/day | Ascertained from hospital registries (pathologic examination) | Age, sex and occupation | 0 vs. ≥1, 5 [2, 10] | 6 |
| Guha N (12) [2007], South America | Case-control | M&F, >0 | 454 | 95 | Self-reported brushing frequency: 0; <1; 1; ≥2/day | Ascertained from hospital registries (histologically or cytologically confirmed diagnosis of squamous cell carcinoma) | Age, sex, country/center, education, tobacco pack-years, cumulative alcohol consumption | <1 vs. ≥2, 0.39 [0.11, 1.31] | 8 |
| Sato F (23) [2011], Asia | Case-control | M&F, ≥20 | 1,617 | 387 | Self-reported brushing frequency: 1; ≥2/day | Ascertained from study visits and review of hospital discharge lists and medical charts | Age, sex, amount of smoking and alcohol consumption, intake of vegetables, fruits, BMI, occupation, and number of remaining teeth | 1 vs. 2, 0.67 [0.12, 3.88] |
7 |
| Dar N (24) [2013], Asia | Case-control | M&F, >18 | 2,338 | 702 | Self-reported brushing frequency: 0; <1; ≥1/day | Ascertained from hospital registries and completed questionnaires | Age, ethnicity, residence, education, wealth score, fruit and vegetable intake, smoking, gutka chewing, alcohol consumption and cumulative use of hookah, cigarette | 0 vs. ≥1, 2.27 [1.29, 4] | 7 |
| Menya D (25) [2019], Africa | Case-control | M&F, ≥18 | 870 | 430 | Self-reported brushing frequency: 0; ≥1/day | Ascertained from hospital registries morphological examination and pathologic examination | Age, sex, ethnicity, alcohol+tobacco, alcohol intensity, very hot/hot/warm beverage drinking, family history of esophageal cancer, education, brushing frequency, brush type, Sum of number of Decayed, Missing, Filled Teeth, dental fluorosis | 0 vs. ≥1, 2.5 [1, 6] | 8 |
| Chen X (26) [2017], Asia | Case-control | M&F, ≥40 | 1,377 | 613 | Self-reported brushing frequency: ≤1; ≥2 /day | Ascertained from study visits, the local Cancer Registry and review of hospital discharge lists and medical charts | Age, sex, education, marital status, tobacco smoking, alcohol drinking, tea drinking, family history of esophageal cancer, daily consumption of pickled vegetables, daily consumption of fresh fruits, and wealth score. | ≤1 vs. ≥2, 1.81 [1.37, 2.38] | 8 |
| Mmbaga B (10) [2020], Africa | Case-control | M&F, ≥18 | 623 | 310 | Self-reported brushing frequency: 0; ≥1 /day | Ascertained from hospital registries | Age, sex, education, region/district and ethnicity, alcohol, tobacco | 0 vs. ≥1, 2.77 [1.20, 6.43] | 8 |
| Chen T (27) [2015], Asia | Case-control | M&F, ≥45 | 1,391 | 619 | Self-reported brushing frequency: <2; ≥2/day | Ascertained from hospital registries | Age, sex, family size | <2 vs. ≥2, 1.91 [1.49, 2.44] | 7 |
| Chen X (28) [2015], Asia | Case-control | M&F | 571 | 171 | Self-reported brushing frequency: <2; ≥2/day | Ascertained from study visits and hospital registries | Age, sex, education, smoking, alcohol drinking, family history of esophageal cancer | <2 vs. ≥2, 3.18 [1.52, 6.67] | 7 |
| Abnet C (29) [2008], Asia | Case-control | M&F, ≥18 | 843 | 283 | Self-reported brushing frequency:0; <1; ≥1 /day | Ascertained from hospital registries and Primary Health Care System | Age, sex, place of residence, ethnicity, alcohol drinking, use of tobacco, opium, or both, education in three categories, number of appliances, and fruit and vegetable intake | 0 vs. ≥1, 2.37 [1.42, 3.97] | 8 |
| Ahrens W (30) [2014], Europe | Case-control | M&F | 1,966 | 234 | Self-reported brushing frequency:0; ≥1/day | Ascertained from study visits and hospital registries | Age, sex, study center; smoking status, cumulative tobacco consumption, alcohol drinking duration, education, consumption of fruits and vegetables | 0 vs. ≥1, 1.56 [1.08, 2.25] | 7 |
| Ekheden I (9) [2020], Asia | Case-control | M&F, ≥40 | 3,188 | 1,210 | Self-reported brushing frequency: ≤1; ≥2/day | Ascertained from local hospitals and the local cancer registry | Age, sex, duration, marital status, occupation, family wealth score, body mass index 10 years before, tea drinking, history of esophageal cancer among first-degree relatives, smoking, alcohol consumption | ≤1 vs. ≥2, 2.14 [1.72, 2.65] | 7 |
| Nasrollahzadeh D (31) [2012], Asia | Case-control | M&F | 817 | 293 | Self-reported brushing frequency:0; ≥1 /day | Ascertained from study visits, family health census and hospital registries | Age, sex, residence area, ethnicity, alcohol consumption, tobacco or opium use, education and vegetable/fruit consumption | 0 vs. ≥1, 4.12 [2.05, 8.28] | 8 |