Table 3.
Relative risk of cancer by smoking according to trajectories of body shape in women (Nurses’ Health Study) and men (Health Professionals Follow-up Study)a
| Lean-stable | Lean-moderate increase | Lean-marked increase | Medium-stable | Heavy-stable/increase | P for interactionb | |
|---|---|---|---|---|---|---|
| Women | ||||||
| Total cancer | ||||||
| Ever smokers (N=7,082) | 1 (reference) | 0.99 (0.92–1.07) | 1.07 (0.99–1.16) | 1.00 (0.93–1.07) | 1.00 (0.92–1.10) | 0.005 |
| Never smokers (N=4,380) | 1 (reference) | 1.22 (1.10–1.34)c | 1.35 (1.22–1.50) | 1.14 (1.03–1.26) | 1.46 (1.30–1.64)e | |
| Obesity-related cancerf | ||||||
| Ever smokers (N=3,591) | 1 (reference) | 1.14 (1.03–1.27) | 1.33 (1.19–1.48) | 0.97 (0.88–1.08) | 1.15 (1.02–1.31) | 0.08 |
| Never smokers (N=2,809) | 1 (reference) | 1.23 (1.08–1.39) | 1.48 (1.30–1.68) | 1.12 (0.99–1.27) | 1.50 (1.30–1.74)d | |
| Colorectal cancer | ||||||
| Ever smokers (N=675) | 1 (reference) | 0.97 (0.76–1.23) | 1.25 (0.97–1.61) | 0.97 (0.77–1.22) | 1.26 (0.95–1.67) | 0.54 |
| Never smokers (N=456) | 1 (reference) | 0.98 (0.72–1.33) | 1.20 (0.87–1.65) | 1.11 (0.82–1.51) | 1.68 (1.19–2.37) | |
| Pancreatic cancer | ||||||
| Ever smokers (N=179) | 1 (reference) | 1.09 (0.67–1.78) | 1.60 (0.98–2.61) | 1.09 (0.69–1.73) | 1.11 (0.61–2.00) | 0.25 |
| Never smokers (N=145) | 1 (reference) | 1.31 (0.76–2.26) | 1.13 (0.63–2.05) | 1.25 (0.72–2.15) | 1.84 (1.00–3.40) | |
| Kidney cancer | ||||||
| Ever smokers (N=120) | 1 (reference) | 1.20 (0.65–2.22) | 1.78 (0.97–3.27) | 1.03 (0.57–1.88) | 1.59 (0.81–3.14) | 0.85 |
| Never smokers (N=92) | 1 (reference) | 1.41 (0.66–3.03) | 2.17 (1.03–4.56) | 1.10 (0.50–2.41) | 2.57 (1.16–5.66) | |
| Postmenopausal breast cancer | ||||||
| Ever smokers (N=1,951) | 1 (reference) | 1.21 (1.05–1.39) | 1.30 (1.12–1.51) | 0.94 (0.81–1.07) | 0.99 (0.83–1.18) | 0.10 |
| Never smokers (N=1,503) | 1 (reference) | 1.47 (1.24–1.75) | 1.60 (1.34–1.92)c | 1.25 (1.05–1.49)d | 1.33 (1.08–1.65)c | |
| Endometrial cancer | ||||||
| Ever smokers (N=324) | 1 (reference) | 1.17 (0.79–1.72) | 1.62 (1.10–2.39) | 1.15 (0.79–1.66) | 2.25 (1.51–3.34) | 0.48 |
| Never smokers (N=340) | 1 (reference) | 0.84 (0.58–1.22) | 1.50 (1.06–2.13) | 0.77 (0.53–1.11) | 1.97 (1.36–2.86) | |
| Ovarian cancer | ||||||
| Ever smoking (N=271) | 1 (reference) | 0.86 (0.59–1.25) | 0.81 (0.54–1.22) | 0.95 (0.68–1.34) | 0.83 (0.52–1.31) | 0.50 |
| Never smoking (N=205) | 1 (reference) | 0.91 (0.59–1.39) | 1.06 (0.69–1.63) | 0.76 (0.49–1.18) | 0.86 (0.50–1.47) | |
|
| ||||||
| Men | ||||||
| Total cancerg | ||||||
| Ever smokers (N=3,235) | 1 (reference) | 0.96 (0.85–1.08) | 1.03 (0.93–1.15) | 0.98 (0.86–1.11) | 1.17 (1.02–1.34) | 0.11 |
| Never smokers (N=1,741) | 1 (reference) | 1.20 (1.03–1.40)c | 1.09 (0.94–1.25) | 1.13 (0.95–1.34) | 1.16 (0.96–1.41) | |
| Obesity-related cancerh | ||||||
| Ever smokers (N=1,125) | 1 (reference) | 1.04 (0.86–1.27) | 1.07 (0.89–1.28) | 0.99 (0.79–1.23) | 1.05 (0.82–1.34) | 0.09 |
| Never smokers (N=707) | 1 (reference) | 1.40 (1.10–1.79)c | 1.12 (0.88–1.41) | 1.38 (1.05–1.82)c | 1.38 (1.01–1.88) | |
| Colorectal cancer | ||||||
| Ever smokers (N=359) | 1 (reference) | 1.25 (0.87–1.79) | 1.21 (0.86–1.69) | 1.08 (0.72–1.64) | 1.55 (1.02–2.35) | 0.55 |
| Never smokers (N=233) | 1 (reference) | 1.51 (0.98–2.35) | 1.26 (0.83–1.91) | 1.57 (0.97–2.53) | 1.33 (0.76–2.34) | |
| Pancreatic cancer | ||||||
| Ever smokers (N=148) | 1 (reference) | 0.62 (0.34–1.12) | 1.18 (0.73–1.89) | 0.97 (0.54–1.74) | 0.90 (0.46–1.75) | 0.03 |
| Never smokers (N=83) | 1 (reference) | 1.27 (0.60–2.70) | 1.04 (0.51–2.10) | 1.34 (0.59–3.05) | 2.68 (1.24–5.80)c | |
| Kidney cancer | ||||||
| Ever smokers (N=130) | 1 (reference) | 1.04 (0.60–1.80) | 0.83 (0.49–1.40) | 0.81 (0.43–1.55) | 1.01 (0.52–1.95) | 0.26 |
| Never smokers (N=72) | 1 (reference) | 0.93 (0.43–2.03) | 1.08 (0.54–2.13) | 1.53 (0.71–3.26) | 0.46 (0.13–1.64) | |
| Advanced prostate canceri | ||||||
| Ever smokers (N=398) | 1 (reference) | 1.00 (0.73–1.37) | 0.93 (0.69–1.24) | 0.93 (0.65–1.32) | 0.49 (0.30–0.81) | 0.18 |
| Never smokers (N=296) | 1 (reference) | 1.40 (0.97–2.03) | 1.03 (0.72–1.47) | 1.13 (0.73–1.74) | 1.04 (0.63–1.73)c | |
Abbreviations: CI, confidence interval; RR, relative risk.
Follow-up started at age 62. RRs were estimated from multivariable Cox proportional hazards model with adjustment for the same set of covariates as in Table 1.
Global likelihood ratio test with 4 degrees of freedom was used to compare the model with the product terms between smoking (binary: ever vs. never smoking) and the trajectory groups (indicator variables for the 4 non-reference groups) to the model without these terms.
P for interaction≤0.05, >0.01 by individual Wald test for each of the non-reference trajectory groups. A product term was created by multiplying the binary variable for each of the trajectory groups (1, non-reference group under test, 0, reference group) and the binary smoking variable (ever vs. never).
P for interaction≤0.01, >0.001 by individual Wald test.
P for interaction≤0.001, >0.0001 by individual Wald test.
Including cancers of the colorectum, esophagus (adenocarcinoma only), pancreas, kidney, breast (postmenopause), endometrium, ovaries, liver, and gallbladder.
Excluding non-advanced prostate cancer.
Including cancers of the colorectum, esophagus (adenocarcinoma only), pancreas, kidney, prostate (advanced cancer only), liver, and gallbladder.
Advanced prostate cancer defined as cases that had spread outside the prostate (stage T3b/T4, N1, or M1) or lethal tumors.