Summary of 14 case-control studies included in the systematic review; Lissowska et al5 was included in the pooled analysis by Hosgood et al14
| Author and study location | Study design (all case-control); numbers of cases and controls; outcome assessment | Cooking fuel type(s); assessment of duration of use | Reference category clearly using clean fuel(s) | Adequacy of adjustment | Non-smoker analysis* | Results: adjusted OR (95% CI) |
|---|---|---|---|---|---|---|
| Behera, India17 | Hospital-based cases: 67 (F); pathologically confirmed controls: 46 (F) | Biomass for cooking; duration: current fuel use | YEs: use of LPG | Moderate | Not reported | Women: use of biomass for cooking: OR=3.59 (1.07 to 11.97) |
| Gupta, India15 | Hospital-based cases: 235 (M), 30 (F); pathologically confirmed controls: 525 (2 per case) | Wood for cooking and for heating; duration: <45 and >45 years of use | No: never used wood | Moderate | Not reported | Use of wood for cooking: Men: 1–45 years: OR=0.94 (0.58 to 1.54) >45 years: OR=0.87 (0.58 to 1.30) Women: 1–45 years: OR=0.74 (0.20 to 2.65) >45 years: OR=1.11 (0.34 to 3.60) Use of wood for heating: Men: 1–45 years: OR=2.62 (0.47 to 14.5) Women: 1–45 years: OR= 2.78 (0.97 to 7.98) |
| Sapkota, India11 | Hospital-based cases: 793 (88% M); 80% cases pathologically confirmed controls: 718 | Wood for cooking; duration: always used wood | Yes: always used modern cooking fuel† | Moderate | Only for all solid fuels (biomass and other solid fuels) | Use of wood for cooking: Men: OR=1.30 (0.90 to 1.87) Women: OR=1.01 (0.42 to 2.41) Men and women non-smokers: OR=0.75 (0.45 to 1.24) |
| Gao, China18 | Population-based cases: 672 (F) 80%; pathologically confirmed controls: 735 | Wood for cooking; duration: current wood use | No: not currently using wood | Moderate | Not reported | Women: Use of wood for cooking: OR=1.0 (0.6 to 1.8) |
| Liu China16 | Hospital-based cases: 224 (M) and 92 (F); 32% pathologically confirmed controls: 224 (M) and 92 (F) | Wood for cooking; duration: current wood use | No: not currently using wood | Weak | Not reported | Use of wood for cooking: Men: estimated (unadjusted) OR=1.39 (0.44 to 4.42) Women: estimated (unadjusted) OR=0.84 (0.14 to 5.0) |
| Ko, Taiwan19 | Hospital-based cases: 105 (F); pathologically confirmed controls: 105 (F) | Wood or charcoal for cooking; duration: cooking before 20 years of age, 20–40 and after 40 | Yes: no cooking/gas | Moderate | Cases are non-smoking women | Women: use of wood/charcoal for cooking: OR=2.7 (0.9 to 8.9) |
| Koo, Hong Kong20 | Population-based (poorly described) cases: 200 (F); no information on histology controls: 200 (F) | Wood or grass for cooking; duration: ever used wood/grass | No: never used wood/grass | Weak | Not reported | Women: use of biomass for cooking: OR=0.74 (95% CI not reported), p=0.50 |
| Lee, Taiwan4 | Hospital-based cases: 236 (M) and 291 (F); pathologically confirmed controls: 805 (M and F) | Wood or charcoal for cooking; duration: asked about habitual cooking practice age 20–40 years | YEs: no cooking or gas | Strong | Not reported | Women: use of wood/charcoal for small-cell carcinoma: OR=3.5 (0.9 to12.9); use of wood/charcoal for adeno-carcinoma: OR=3.3 (1.4 to 8.0) |
| Sobue, Japan6 | Hospital-based cases: 144 (F); pathologically confirmed controls: 731 (F) | Wood or grass for cooking; duration: asked about fuel use at both 15 and 30 years of age | No: not wood or grass | Moderate | Cases are non-smoking women | Women: use of biomass for cooking: OR=1.77 (1.08 to 2.91) |
| Malats, 6 European; Brazil22 | Hospital-based cases: 17 (M) and 105 (F); pathologically confirmed controls: 34 (M) and 87 (F) | Wood for cooking or heating; duration: more than 20 years use | No: not stated | Strong | Cases are non-smoking (M/F combined) | Men and women: use of wood for heating or cooking: OR=2.50 (1.00 to 6.25) |
| Hernandez-Garduno, Mexico7 | Hospital-based cases: 113 (F) pathologically confirmed controls‡: 273 (F) | Wood for cooking; duration: 1–20, 21–50 and >50 years of use | No: never used wood | Strong | Cases are non-smoking women | Women: use of wood for cooking: 1–20 years: OR=0.6 (0.3 to 1.2); 21–50 years: OR=0.6 (0.3 to 1.3); >50 years: OR=1.9 (1.1 to 3.5) |
| Lissowska, 7 European countries5 | Hospital and population cases: 1378 (M) and 323 (F); pathologically confirmed controls: 1422 (M) and 429 (F) | Wood for cooking and heating; duration: exclusive use of wood for cooking | Yes: never used solid fuel | Moderate | Not reported | Use of wood for cooking: Men: OR=1.24 (1.00 to 1.54) Women: OR=1.07 (0.67 to 1.71) |
| Tang, Chinese in Singapore21 | Hospital-based cases: 703 (all F); 674 (96%) pathologically confirmed, remainder radiologically, controls: 1578 (all F) | Wood for cooking; duration: frequency of use | No: less than daily use of wood | Strong | Yes (all women) | Women: use of wood for cooking: current/ex-smokers: OR=1.25 (0.74 to 2.11); never-smokers: OR=0.81 (0.56 to 1.17) |
| Hosgood, pooled studies from Europe, USA, Canada, Asia14 | Hospital and population cases: 4194 (M and F); pathologically confirmed for 3749 (89%) cases, not reported for any of the 445 cases in one study; controls: 5189 (M and F). Incorporates Lissowska5 | Wood for cooking or heating (only from European and North American centres); duration: lifetime predominant wood use | Yes: clean fuels including electricity, oil and gas | Strong | Yes, for M and F combined | Use of wood for cooking and/or heating All subjects: men: OR=1.19 (1.02 to 1.39) women: OR=1.19 (0.94 to 1.51) By smoking status (M and F): ever smoke: OR=1.22 (1.05 to 1.42) never smoke: OR=1.01 (0.74 to 1.37) |
*When not stratified for smoking, all studies with moderate or strong adjustment controlled for smoking.
†Clean fuel reference group includes kerosene.
‡Control group included subjects with TB, interstitial lung disease, COPD, asthma, miscellaneous pulmonary conditions.
§Reanalysis by International Agency for Research on Cancer (IARC) for the current review to provide separate estimates for men and women, and for cooking and heating; also exposure–response analysis based on years of wood use (see text).