Table 1.
Modifiable risk factors with statistically significant association with bladder cancer
| Risk factor | Total MAs | Total primary studies | Total BC cases in specific MA | Outcome type | Comparison | Relative risk (95 % CI) | Confidence interval | POC (%) | Combined POC (%) |
|---|---|---|---|---|---|---|---|---|---|
| Lifestyle factors | |||||||||
| Fruit and vegetable consumption [19] | 1 | 10 | NS | High versus low intake | 0.81 | 0.67–0.99 | 19 | $ | |
| Fruit consumption [19] | 1 | 21 | 9867 | NS | High versus low intake | 0.77 | 0.69–0.87 | 23 | |
| Citrus fruit [20] | 1 | 14 | 7372 | Incidence | High versus low intake | 0.85 | 0.76–0.94 | 15 | |
| Vegetable consumption [19, 21] | 2 (MMA) | 31 unique; 3 duplicate | 8808 unique; 765 duplicate | NS | High versus low intake | 0.83 | 0.75–0.92 | 17 | |
| Cruciferous vegetable [19] | 1 | 11 | 6496 | NS | High versus low intake | 0.84 | 0.77–0.91 | 16 | |
| Processed meat [33] | 1 | 11 | 7562 | NS | High versus low intake | 1.22 | 1.04–1.43 | 18 | $ |
| Vitamin A [36] | 1 | 11 | 4990 | NS | High versus low intake (dietary and supplements) and blood levels | 0.82 | 0.65–0.95 | 18 | |
| Vitamin A supplement [36] | 1 | 5 | 1403 | Incidence | Supplementation versus placebo or no supplementation | 0.64 | 0.47–0.82 | 36 | |
| Vitamin D [39] | 1 | 5 | 2238 | Incidence/mortality | High versus low serum level | 0.75 | 0.65–0.87 | 25 | |
| Vitamin E [38] | 1 | 15 | 5224 | Incidence | High versus low intake | 0.82 | 0.74–0.90 | 18 | |
| Folate [41] | 1 | 13 | 6280 | Incidence | High versus low intake | 0.84 | 0.72–0.96 | 16 | |
| Selenium [42] | 1 | 7 | 1014 | Incidence | High versus low serum or toenail level | 0.61 | 0.42–0.87 | 39 | |
| Antioxidant supplement [44] | 1 | 4 | NR | Incidence | Supplementation versus placebo or no supplementation | 1.52 | 1.06–2.17 | 34 | |
| Obesity [46] | 1 | 12 | NS | Obese versus normal body weight | 1.10 | 1.03–1.18 | 9 | ||
| Cigarette smoking [10] | 1 | 13 | 9129 | Incidence | Current cigarette smokers versus never smokers | 3.14 | 2.53–3.75 | 68 | $ |
| 1 | 12 | 8659 | Incidence | Former cigarette smokers versus never smokers | 1.83 | 1.52–2.14 | 45 | ||
| Pipe smoking [52] | 1 | 6 | 34 | Incidence | Pipe only smokers versus never smokers | 1.90 | 1.2–3.1 | 47 | |
| Cigar smoking [52] | 1 | 6 | 52 | Incidence | Cigar only smokers versus never smokers | 2.30 | 1.6–3.5 | 57 | |
| Physical activity [56] | 1 | 7 | NR | Incidence | High versus low | 0.86 | 0.77–0.95 | 14 | $ |
| Combined POC | 81.8 | ||||||||
| Occupational factors [61] | |||||||||
| Tobacco workers | 1 | 3 | 87 | Incidence | Versus any other occupation | 1.72 | 1.37–2.15 | 42 | |
| Dye workers | 1 | 21 | 344 | Incidence | Versus any other occupation | 1.58 | 1.32–1.90 | 37 | |
| Chimney sweeps | 1 | 4 | 146 | Incidence | Versus any other occupation | 1.53 | 1.30–1.81 | 35 | |
| Nurses | 1 | 13 | 1195 | Incidence | Versus any other occupation | 1.49 | 1.06–2.08 | 33 | |
| Rubber workers | 1 | 45 | 1263 | Incidence | Versus any other occupation | 1.49 | 1.37–1.61 | 33 | |
| Waiters | 1 | 9 | 1146 | Incidence | Versus any other occupation | 1.43 | 1.34–1.52 | 30 | |
| Aluminium workers | 1 | 21 | 977 | Incidence | Versus any other occupation | 1.41 | 1.29–1.55 | 29 | |
| Hairdressers | 1 | 47 | 1445 | Incidence | Versus any other occupation | 1.32 | 1.24–1.40 | 24 | |
| Printers | 1 | 42 | 1724 | Incidence | Versus any other occupation | 1.23 | 1.17–1.30 | 19 | |
| Seamen | 1 | 10 | 1791 | Incidence | Versus any other occupation | 1.23 | 1.17–1.29 | 19 | |
| Oil and petroleum workers | 1 | 17 | 637 | Incidence | Versus any other occupation | 1.20 | 1.06–1.37 | 17 | |
| Shoe and leather workers | 1 | 39 | 1091 | Incidence | Versus any other occupation | 1.20 | 1.12–1.29 | 17 | |
| Plumbers | 1 | 8 | 1418 | Incidence | Versus any other occupation | 1.20 | 1.14–1.27 | 17 | |
| Sales agents | 1 | 91 | 11923 | Incidence | Versus any other occupation | 1.17 | 1.15–1.20 | 15 | |
| Artistic workers | 1 | 34 | 1678 | Incidence | Versus any other occupation | 1.16 | 1.10–1.22 | 14 | |
| Cooks and stewards | 1 | 15 | 1117 | Incidence | Versus any other occupation | 1.15 | 1.08–1.22 | 13 | |
| Chemical process workers | 1 | 79 | 3712 | Incidence | Versus any other occupation | 1.14 | 1.10–1.19 | 12 | |
| Metal workers | 1 | 62 | 5461 | Incidence | Versus any other occupation | 1.14 | 1.11–1.18 | 12 | |
| Drivers | 1 | 57 | 10396 | Incidence | Versus any other occupation | 1.14 | 1.11–1.16 | 12 | |
| Fishermen | 1 | 7 | 1525 | Incidence | Versus any other occupation | 1.13 | 1.08–1.19 | 12 | |
| Painters | 1 | 43 | 3472 | Incidence | Versus any other occupation | 1.13 | 1.09–1.17 | 12 | |
| Assistant nurses | 1 | 2 | 812 | Incidence | Versus any other occupation | 1.12 | 1.04–1.20 | 11 | |
| Domestic assistants | 1 | 35 | 1776 | Incidence | Versus any other occupation | 1.12 | 1.07–1.18 | 11 | |
| Launderers and dry cleaners | 1 | 19 | 767 | Incidence | Versus any other occupation | 1.12 | 1.04–1.21 | 11 | |
| Public safety workers–police | 1 | 30 | 2382 | Incidence | Versus any other occupation | 1.11 | 1.07–1.16 | 10 | |
| Physicians | 1 | 10 | 858 | Incidence | Versus any other occupation | 1.11 | 1.03–1.19 | 10 | |
| Clerical workers | 1 | 148 | 21109 | Incidence | Versus any other occupation | 1.11 | 1.10–1.13 | 10 | |
| Electrical workers | 1 | 45 | 5314 | Incidence | Versus any other occupation | 1.11 | 1.07–1.14 | 10 | |
| Military personnel | 1 | 14 | 2091 | Incidence | Versus any other occupation | 1.11 | 1.05–1.18 | 10 | |
| Mechanics | 1 | 127 | 67195 | Incidence | Versus any other occupation | 1.11 | 1.09–1.13 | 10 | |
| Smelting workers | 1 | 24 | 2319 | Incidence | Versus any other occupation | 1.11 | 1.06–1.16 | 10 | |
| Transport workers | 1 | 35 | 5243 | Incidence | Versus any other occupation | 1.10 | 1.06–1.13 | 9 | |
| Glass makers, etc. | 1 | 29 | 2219 | Incidence | Versus any other occupation | 1.10 | 1.05–1.15 | 9 | |
| Textile workers | 1 | 79 | 3822 | Incidence | Versus any other occupation | 1.10 | 1.06–1.14 | 9 | |
| Waiters and bartenders | 1 | 34 | 1179 | Incidence | Versus any other occupation | 1.10 | 1.01–1.19 | 9 | |
| Building caretakers | 1 | 4 | 3246 | Incidence | Versus any other occupation | 1.09 | 1.06–1.13 | 8 | |
| Health care workers | 1 | 20 | 1072 | Incidence | Versus any other occupation | 1.09 | 1.06–1.12 | 8 | |
| Food manufacturing workers | 1 | 33 | 3559 | Incidence | Versus any other occupation | 1.08 | 1.04–1.12 | 7 | |
| Postal workers | 1 | 4 | 1791 | Incidence | Versus any other occupation | 1.08 | 1.03–1.13 | 7 | |
| Packers, loaders, and warehouse workers | 1 | 25 | 3586 | Incidence | Versus any other occupation | 1.08 | 1.04–1.13 | 7 | |
| Shop workers | 1 | 4 | 6068 | Incidence | Versus any other occupation | 1.07 | 1.05–1.10 | 7 | |
| Technical workers, etc. | 1 | 37 | 11579 | Incidence | Versus any other occupation | 1.04 | 1.02–1.06 | 4 | |
| Economically inactive | 1 | 2 | 23436 | Incidence | Versus any other occupation | 0.96 | 0.95–0.97 | 4 | |
| Religious and legal workers, etc. | 1 | 6 | 1754 | Incidence | Versus any other occupation | 0.93 | 0.88–0.97 | 7 | |
| Forestry workers | 1 | 53 | 10865 | Incidence | Versus any other occupation | 0.88 | 0.86–0.90 | 12 | |
| Teachers | 1 | 30 | 3884 | Incidence | Versus any other occupation | 0.85 | 0.82–0.87 | 15 | |
| Gardeners | 1 | 10 | 3308 | Incidence | Versus any other occupation | 0.78 | 0.75–0.81 | 22 | |
| Farmers | 1 | 73 | 16607 | Incidence | Versus any other occupation | 0.69 | 0.68–0.71 | 31 | |
BC bladder cancer, MA meta-analysis, MMA meta-meta-analysis, NS not specified, POC probability of causation
$Risk factors and protective factors that have been included in the combined POC. The POC can be interpreted as the proportion of exposed cases that are attributable to the exposure