Table 2.
Associationsa) between active and passive smoking and the risk of papillary thyroid cancer assessed using casecontrol study design
| Men |
Women |
|||
|---|---|---|---|---|
| Cases/Controls | OR (95% CI) | Cases/Controls | OR (95% CI) | |
| Active smoking (total) | 417/4,170 | 1,725/17,250 | ||
| Active smoking status | ||||
| Never | 122/1,115 | 1.00 | 1,664/16,515 | 1.00 |
| Past | 202/1,598 | 1.15 (0.91-1.47) | 36/250 | 1.27 (0.88-1.82) |
| Current | 93/1,457 | 0.57 (0.43-0.76) | 25/475 | 0.52 (0.35-0.78) |
| Cumulative smoking dose (pack-year) | ||||
| Never | 122/1,115 | 1.00 | 1,664/16,515 | 1.00 |
| < 20 | 150/1,720 | 0.80 (0.61-1.02) | 43/662 | 0.64 (0.47-0.88) |
| ≥ 20 | 125/1,307 | 0.87 (0.66-1.14) | 11/63 | 1.73 (0.91-3.29) |
| Age at active smoking initiation (yr) | ||||
| Never | 122/1,115 | 1.00 | 1,664/16,515 | 1.00 |
| ≥ 25 | 32/440 | 0.64 (0.44-0.97) | 25/468 | 0.53 (0.35-0.80) |
| < 25 | 259/2,611 | 0.91 (0.71-1.17) | 32/265 | 1.17 (0.72-1.90) |
| Passive smoking (total)b) | 122/1,115 | 1,664/16,515 | ||
| Current exposure to passive smoking | ||||
| No | 99/915 | 1.00 | 1,343/13,536 | 1.00 |
| Yes | 23/200 | 1.06 (0.64-1.75) | 321/2,979 | 1.09 (0.95-1.24) |
| Exposure time to passive smoking (min/day) | ||||
| No | 99/915 | 1.00 | 1,343/13,536 | 1.00 |
| < 20 | 16/130 | 1.15 (0.65-2.01) | 220/1,938 | 1.15 (0.97-1.35) |
| ≥ 20 | 7/70 | 0.93 (0.38-2.09) | 101/1,041 | 0.98 (0.79-1.21) |
| Exposure duration of passive smoking (yr) | ||||
| No | 99/915 | 1.00 | 1,343/13,536 | 1.00 |
| 1-9 | 5/53 | 0.88 (0.34-2.24) | 70/710 | 0.99 (0.76-1.31) |
| ≥ 10 | 9/108 | 0.78 (0.38-1.58) | 168/1,868 | 0.91 (0.77-1.08) |
| Age at passive smoking exposure initiation (yr) | ||||
| No | 99/915 | 1.00 | 1,343/13,536 | 1.00 |
| ≥ 31 | 10/104 | 0.90 (0.45-1.77) | 117/1,135 | 1.05 (0.88-1.32) |
| < 31 | 4/57 | 0.67 (0.19-2.40) | 121/1,443 | 0.85 (0.68-1.05) |
OR, odds ratio; CI, confidence interval.
a)
Conditional logistic regression models (matching variables: age and sex) adjusted for body mass index, education, marital status, and history of chronic diseases were used to estimate the association between active and passive smoking and papillary thyroid cancer risk,
b)
The analyses for the associations between passive smoking and papillary thyroid cancer were conducted among never-smokers.