Colorectal cancer risk by sex and quartiles of pack-years of all tobacco products and of filtered and non-filtered cigarettes
| Q1* | Q2 | Q3 | Q4 | Ptrend† | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n‡ | OR (95% CI) | n | OR (95% CI) | n | OR (95% CI) | n | OR (95% CI) | |||||||||||
| Males (1,109 case-control pairs) | ||||||||||||||||||
| All tobacco | 185/144 | 1.02 (0.76-1.36) | 186/187 | 1.14 (0.86-1.51) | 186/224 | 1.33 (1.00-1.76) | 189/272 | 1.48 (1.12-1.96) | 0.002 | |||||||||
| Filtered cigarettes | 132/116 | 0.95 (0.68-1.32) | 139/132 | 0.91 (0.67-1.26) | 134/162 | 1.11 (0.81-1.51) | 138/173 | 1.06 (0.79-1.42) | 0.63 | |||||||||
| Non-filtered cigarettes | 135/115 | 1.03 (0.75-1.42) | 135/116 | 0.91 (0.65-1.28) | 136/168 | 1.30 (0.96-1.78) | 125/207 | 1.73 (1.27-2.34) | 0.0002 | |||||||||
| Cigars | 38/46 | 1.30 (0.96-1.78) | 39/62 | 1.60 (1.00-2.58) | 0.04 | |||||||||||||
| Pipes | 46/44 | 0.89 (0.55-1.44) | 34/50 | 0.99 (0.61-1.60) | 0.98 | |||||||||||||
| Females (814 case-control pairs) | ||||||||||||||||||
| All tobacco | 72/74 | 1.33 (0.91-1.95) | 73/57 | 0.81 (0.54-1.22) | 68/95 | 1.48 (1.03-2.13) | 73/99 | 1.38 (0.91-1.95) | 0.04 | |||||||||
| Filtered cigarettes | 62/70 | 1.42 (0.95-2.12) | 61/45 | 0.69 (0.45-1.07) | 62/81 | 1.32 (0.88-1.97) | 61/85 | 1.17 (0.78-1.76) | 0.35 | |||||||||
| Non-filtered cigarettes | 27/21 | 0.79 (0.43-1.49) | 26/32 | 1.06 (0.58-1.92) | 27/37 | 1.33 (0.74-2.42) | 25/55 | 2.23 (1.25-3.98) | 0.004 | |||||||||
NOTE: OR and 95% CI are estimated by conditional logistic regression, matched on age and ethnicity, and adjusted for family history of colorectal cancer, body mass index 5 y ago (males only), lifetime hours in recreational activities (males only) and egg, total calcium, non-starch polysaccharides from vegetables, methionine (females only), and alcohol (males only) intake. Two separate models were run in each sex, both with never smokers as the reference category: one model included indicator variables for each quartile of pack-years of all tobacco products, and the other model included indicator variables for each quartile of pack-years for each type of cigarettes (filtered and non-filtered cigarettes), and in men, levels (<median; >median) of pack-years of cigars and pipes. In women, the latter model was further adjusted for pack-years of cigars and pipes (continuous).
↵* Q1, 1st quartile; Q2, 2nd quartile; Q3, 3rd quartile; Q4, 4th quartile. Based on male controls who smoked, the quartile cut points (25th-75th percentile) for total pack-years and pack-years of filtered and non-filtered cigarettes are as follows: >0-12, >12-28.3, >28.3-48, and >48 for all tobacco; >0-10.4, >10.4-23, >23-40, and >40 for filtered cigarettes; and >0-4.8, >4.8-11, >11-24 and >24 for non-filtered cigarettes. Median cut points for pipes and cigars are 1.8 pack-years of cigars and 1.0 pack-years of pipes. Based on female controls who smoked, the quartile cut points (25th-75th percentile) for total pack-years and pack-years of filtered and non-filtered cigarettes are as follows: >0-5.3, >5.3-15, >15-34.7, and >34.7 for all tobacco; >0-7, >7-15.6, >15.6-30, and >30 for filtered cigarettes; and >0-1.4, >1.4-5, >5-11, and >11 for non-filtered cigarettes.
↵† Ptrend is estimated by fitting the medians of each quartile as a continuous variable in the multivariate model.
↵‡ Number of controls/number of cases (never smokers: 363/282 and 528/489 for men and women, respectively).