Table 5.

Colorectal cancer risk by anatomical subsite and quartiles of pack-years of all tobacco products and of filtered and non-filtered cigarettes

nOR (95% CI)nOR (95% CI)nOR (95% CI)nOR (95% CI)
Colon (1,349 case-control pairs)
    All tobacco175/1541.14 (0.87-1.50)197/1710.92 (0.70-1.20)179/1991.18 (0.90-1.54)191/2781.39 (1.07-1.81)0.01
    Filtered cigarettes134/1391.20 (0.89-1.62)154/1370.87 (0.65-1.16)134/1571.08 (0.79-1.46)145/1721.05 (0.79-1.39)0.98
    Non-filtered cigarettes129/1080.90 (0.66-1.23)115/990.92 (0.65-1.31)109/1481.38 (1.00-1.92)111/1761.59 (1.15-2.21)0.001
Rectum (573 case-control pairs)
    All tobacco76/641.13 (0.75-1.69)63/851.78 (1.18-2.70)86/921.41 (0.97-2.07)72/1212.12 (1.43-3.14)0.0003
    Filtered cigarettes62/470.71 (0.44-1.13)49/661.25 (0.80-1.96)66/781.14 (0.74-1.75)51/761.37 (0.88-2.13)0.06
    Non-filtered cigarettes42/501.55 (0.93-2.56)42/511.57 (0.93-2.65)42/461.37 (0.80-2.34)54/891.84 (1.18-2.86)0.02
  • NOTE: OR and 95% CI are estimated by conditional logistic regression, matched on age, sex and ethnicity, and adjusted for family history of colorectal cancer, body mass index 5 y ago, lifetime hours in recreational activities as well as egg, total calcium, non-starch polysaccharides from vegetables, methionine, and alcohol intake. Two separate models were run for each subsite, both with never smokers as the reference category: one model included indicator variables for each quartile of for 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) and 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 controls who smoked, the quartile cut points (25th-75th percentile) for total pack-years are as follows: >0-9.8, >9.8-24.6, >24.6-44, and >44; for pack-years of filtered cigarettes: >0-9.5, >9.5-21, >21-38, and >38; for pack-years of non-filtered cigarettes: >0-4, >4-10, >10-22, and >22.

  • 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: 607/547 and 276/211 for males and females, respectively).