Table 3.

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
nOR (95% CI)nOR (95% CI)nOR (95% CI)nOR (95% CI)
Males (1,109 case-control pairs)
    All tobacco185/1441.02 (0.76-1.36)186/1871.14 (0.86-1.51)186/2241.33 (1.00-1.76)189/2721.48 (1.12-1.96)0.002
    Filtered cigarettes132/1160.95 (0.68-1.32)139/1320.91 (0.67-1.26)134/1621.11 (0.81-1.51)138/1731.06 (0.79-1.42)0.63
    Non-filtered cigarettes135/1151.03 (0.75-1.42)135/1160.91 (0.65-1.28)136/1681.30 (0.96-1.78)125/2071.73 (1.27-2.34)0.0002
    Cigars38/461.30 (0.96-1.78)39/621.60 (1.00-2.58)0.04
    Pipes46/440.89 (0.55-1.44)34/500.99 (0.61-1.60)0.98
Females (814 case-control pairs)
    All tobacco72/741.33 (0.91-1.95)73/570.81 (0.54-1.22)68/951.48 (1.03-2.13)73/991.38 (0.91-1.95)0.04
    Filtered cigarettes62/701.42 (0.95-2.12)61/450.69 (0.45-1.07)62/811.32 (0.88-1.97)61/851.17 (0.78-1.76)0.35
    Non-filtered cigarettes27/210.79 (0.43-1.49)26/321.06 (0.58-1.92)27/371.33 (0.74-2.42)25/552.23 (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).