Table 2.
Epidemiological studies of chewing tobacco and oral cancer.
| Authors | OR (95% CI) |
Men OR (95% CI) |
Women OR (95% CI) |
Frequency/day∗∗ | Duration of use in years∗∗∗ | ||||
|---|---|---|---|---|---|---|---|---|---|
| Tobacco ≤ 5 OR (95% CI) | Tobacco 6–10 OR (95% CI) | Tobacco > 10/OR (95% CI) |
Tobacco ≤ 10 yrs/OR (95% CI) | Tobacco 11–20 yrs/OR (95% CI) | Tobacco > 20 yrs/OR (95% CI) | ||||
| Goud et al. [32] | 8.5 (4.3–16.5) | n/a | n/a | 8.2 (3.0–22.3) | 4.7 (2.0–10.7) | 18.4∗ | n/a | 4.2∗ | 10.2∗ |
| Nandakumar et al. [33] | 12.9 (7.5–22.3) | 3.6 (1.7–7.9) | 25.3 (11.2–57.3) | 9.3 (4.9–17.5) | 12.8 (6.6–25.0) | 16.6 (6.3–44.3) | n/a | n/a | n/a |
| Rao et al. [34] | 3.6 (2.5–5.6) | 3.6 (2.5–5.6) | n/a | n/a | 2.8 (2.2–3.5)+ | 3.8∗ | 1.2 (0.9–1.8) | 3.9 (2.7–5.7) | 4.1∗ |
| Khan et al. [35] | 2.3 (0.7–7.4) | n/a | n/a | n/a | n/a | n/a | n/a | n/a | n/a |
| Wasnik et al. [36] | 7.9 (4.1–13.5) | n/a | n/a | 2.1∗ | 8.1 (3.7–17.9) | 20.0 (8.1–48.9) | n/a | n/a | 10.9 (5.9–20.0) |
| Dikshit and kanhere [37] | 5.8 (3.6–9.5) | 5.8 (3.6–9.5) | n/a | 2.0 (1.0–3.8) | 6.7 (3.7–12.1) | 13.9 (7.1–27.2) | n/a | n/a | n/a |
| Znaor et al. [40] | 5.0 (4.2–5.9) | 5.0 (4.2–5.9) | n/a | 5.0∗ | 11.9 (8.9–15.9)++ | n/a | n/a | 3.1 (2.5–3.8)+++ | 9.5∗ |
| Gangane et al. [42] | 10.0 (6.7–14.8) | n/a | n/a | n/a | n/a | n/a | n/a | n/a | n/a |
| Subapriya et al. [41] | 2.9∗ | n/a | n/a | n/a | n/a | n/a | 2.9∗ | 2.5∗ | 2.7∗ |
| Basu et al. [43] | 2.0 (0.9–4.4) | n/a | n/a | n/a | n/a | n/a | n/a | n/a | n/a |
| Jayalekshmi et al. [45] | 5.5 (3.3–9.0) | n/a | 5.5 (3.3–9.0) | 3.3 (1.7–6.4) | 7.8 (4.4–13.9) | 9.2 (4.5–18.7) | n/a | n/a | n/a |
| Jayalekshmi et al. [46] | 5.4 (3.0–9.0) | 5.4 (3.0–9.0) | n/a | 1.9 (1.2–2.8) | n/a | n/a | n/a | n/a | n/a |
| Pednekar et al. [47] | 1.4 (1.0–2.1)∗∗∗∗ | 1.4 (1.0–2.1) | n/a | 1.1 (0.9–1.4) | 1.1 (0.9–1.4) | n/a | 0.8 (0.4–1.7) | 1.0 (0.7–1.4) | 1.1 (1–1.4) |
| Madani et al. [48] | 8.3 (5.4–13.0) | n/a | n/a | n/a | n/a | n/a | n/a | n/a | n/a |
| Ray et al. [49] | 3.9 (2.4–6.1) | 2.8 (1.5–5.1) | 6.4 (3.2–12.7) | n/a | n/a | n/a | n/a | n/a | n/a |
OR: odds ratio, CI: confidence interval, ∗95% CI not reported and/or could not be calculated, ∗∗daily frequency in number of times tobacco is chewed in a day, ∗∗∗total duration of habit in “years,” ∗∗∗∗for cancer of lip, oral cavity, and pharynx only, n/a: not available, +1–10/day, ++>5/day, +++0–19 years, and nonchewers taken as reference category. Frequency/intensity OR are for both genders.