Table 3.

Marijuana smoking and the risk of HNC

CaseControlsOR* (95% CI)
Total4,0295,015
Marijuana smoking
    Never3,5384,1991.00 (reference)
    Ever4027360.88 (0.67-1.16)
    Missing8980
    P for heterogeneity0.07
Frequency of marijuana smoking (times per day)
    Never3,3393,3191.00
    0-12986300.87 (0.61-1.25)
    >1-349610.71 (0.35-1.47)
    >342420.87 (0.40-1.89)
    Missing9466
    P for trend0.26
    P for heterogeneity0.03
Duration of marijuana smoking (in years)
    Never3,3393,3191.00 reference
    >0-51503190.81 (0.53-1.23)
    >5-10651290.87 (0.48-1.57)
    >10-20741450.82 (0.46-1.44)
    >201001400.94 (0.53-1.66)
    Missing9466
    P for trend0.77
    P for heterogeneity0.36
Cumulative exposure (joint-year),
    Never3,3393,3191.00 (reference)
    >0-22084760.89 (0.60-1.31)
    >2-536770.70 (0.31-1.56)
    >51451800.86 (0.54-1.37)
    Missing9466
    P for trend0.22
    P for heterogeneity0.04
  • * Random-effects estimates. Adjusted for age (categorical), sex, race, education level, study, pack-year (continuous), alcohol duration (continuous), duration of smoking pipe (continuous), and duration of smoking cigar (continuous). Likelihood heterogeneity test by study.

  • Tampa study excluded.

  • A joint-year is the number of joints per day multiplied by the duration of marijuana smoking in years (1 joint-year being equivalent to 1 joint per day for 1 y or 365 joints lifetime).