Table 3.

IRs, HRs, and 95% CI values for testicular cancer (n = 119 cases) by exposure to lifetime level of cannabis use in 45,250 conscripts with data available on all study covariates

Cases/noncasesCrude incidence rate per 10,000 PYCrude modelModel 1aModel 2bModel 3c
Study covariatesNIR (95% CI)HR (95% CI)HR (95% CI)HR (95% CI)HR (95% CI)
Lifetime level of cannabis used
 Never use of any drugs102/39,9750.64 (0.53–0.77)1.001.001.001.00
 1–4 times6/2,7040.57 (0.25–1.26)0.88 (0.39–2.01)0.90 (0.40–2.05)0.94 (0.41–2.17)0.95 (0.41–2.19)
 5–10 times4/8611.20 (0.45–3.19)1.86 (0.68–5.05)1.90 (0.70–5.15)2.13 (0.77–5.90)2.15 (0.77–5.95)
 11–50 times2/7280.70 (0.18–2.81)1.09 (0.27–4.43)1.04 (0.26–4.25)1.25 (0.30–5.15)1.17 (0.28–4.85)
 More than 50 times5/8631.56 (0.65–3.74)2.40 (0.98–5.88)2.32 (0.94–5.70)2.68 (1.06–6.77)2.57 (1.02–6.50)
Birth year
 194910/2,4271.06 (0.57–1.97)1.001.001.001.00
 195016/7,8360.52 (0.32–0.85)0.49 (0.22–1.08)0.50 (0.23–1.10)0.49 (0.22–1.09)0.50 (0.23–1.10)
 195193/34,8680.67 (0.54–0.82)0.63 (0.33–1.22)0.65 (0.34–1.25)0.64 (0.33–1.24)0.65 (0.34–1.25)
Cryptorchidism
 No115/44,8970.64 (0.54–0.77)1.001.001.00
 Yes4/2344.23 (1.59–11.27)6.59 (2.43–17.86)6.37 (2.35–17.28)6.24 (2.30–16.97)
Parental testicular cancer
 No118/45,0630.66 (0.55–0.79)1.001.001.00
 Yes1/683.58 (0.50–25.40)5.46 (0.76–39.05)4.84 (0.67–34.91)4.62 (0.64–33.60)
Tobacco smoking
 Never46/18,7760.61 (0.46–0.82)1.001.001.00
 1–5 cigarettes/day16/5,0040.80 (0.49–1.30)1.31 (0.74–2.31)1.37 (0.77–2.44)1.38 (0.77–2.46)
 6–10 cigarettes/day18/9,3490.48 (0.30–0.77)0.79 (0.46–1.36)0.82 (0.47–1.44)0.82 (0.47–1.44)
 11–20 cigarettes/day33/10,4200.80 (0.57–1.13)1.30 (0.83–2.04)1.40 (0.87–2.26)1.40 (0.87–2.26)
 More than 20 cigarettes/day6/1,5820.98 (0.44–2.18)1.58 (0.68–3.71)1.87 (0.77–4.54)1.84 (0.76–4.46)
Alcohol consumption (g of 100% alcohol/week)
 Abstainers (0 g)10/2,7700.90 (0.48–1.67)1.001.001.00
 Light (1–100 g)91/33,7310.67 (0.55–0.83)0.75 (0.39–1.44)0.68 (0.35–1.34)0.68 (0.35–1.34)
 Moderate (101–250 g)17/7,3110.59 (0.37–0.95)0.65 (0.30–1.42)0.50 (0.22–1.14)0.50 (0.22–1.15)
 Heavy (more than 250 g)1/1,3190.20 (0.03–1.41)0.22 (0.03–1.70)0.12 (0.01–1.01)0.13 (0.02–1.04)
  • aModel 1 adjusted for conscript's birth year, conscript's cryptorchidism, and paternal history of testicular cancer.

  • bModel 2 adjusted for conscript's birth year, conscript's frequency of tobacco smoking, and conscript's alcohol consumption.

  • cModel 3 adjusted for all covariates in the table.

  • dExposure to ever use of cannabis before conscription (with or without use of any other illicit drugs).