Table 2.
Hazard Ratios for Incident Colon Cancer and Rectal Cancer (Competing-Risks Model) in the Nurses’ Health Study, 1980–2010
| Risk Factor | Colorectal Cancer (n = 1,759a) | Colon Cancer (n = 1,342) | Rectal Cancer (n = 376) | P Value | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| HRb | 95% CI | P Value | HRb | 95% CI | P Value | HRb | 95% CI | P Value | Colon vs. Rectal | |
| Age (years; 60 vs. 50) | 1.81 | 1.70, 1.92 | <0.0001 | 1.85 | 1.72, 1.98 | <0.0001 | 1.71 | 1.50, 1.96 | <0.0001 | 0.33 |
| Family history of colon or rectal cancer (yes vs. no)c | 1.45 | 1.29, 1.63 | <0.0001 | 1.50 | 1.31, 1.71 | <0.0001 | 1.26 | 0.96, 1.66 | 0.095 | 0.27 |
| Red meat intake (servings/day per year; 1 vs. 0) | 1.01 | 0.87, 1.18 | 0.87 | 1.02 | 0.86, 1.21 | 0.81 | 0.99 | 0.70, 1.40 | 0.96 | 0.88 |
| Processed meat intake (servings/day per year; 1 vs. 0) | 1.11 | 0.92, 1.33 | 0.29 | 1.12 | 0.91, 1.39 | 0.28 | 1.13 | 0.75, 1.71 | 0.57 | 0.98 |
| Folate intake (µg/day per year; 600 vs. 200) | 0.83 | 0.74, 0.95 | 0.004 | 0.85 | 0.74, 0.97 | 0.021 | 0.77 | 0.58, 1.02 | 0.071 | 0.55 |
| Smoking history (total pack-years; 40 vs. 0) | 1.20 | 1.10, 1.31 | <0.0001 | 1.21 | 1.09, 1.33 | 0.0002 | 1.27 | 1.05, 1.53 | 0.013 | 0.64 |
| BMI (units per year; 30 vs. 20)d | 1.37 | 1.19, 1.57 | <0.0001 | 1.32 | 1.13, 1.56 | 0.0006 | 1.50 | 1.10, 2.04 | 0.011 | 0.49 |
| Physical activity level (MET-hours/week per year; 21 vs. 2) | 0.61 | 0.48, 0.76 | <0.0001 | 0.55 | 0.42, 0.71 | <0.0001 | 0.89 | 0.56, 1.41 | 0.63 | 0.067 |
| Height (inches per year; 67 vs. 61) | 1.24 | 1.09, 1.41 | 0.001 | 1.24 | 1.07, 1.44 | 0.003 | 1.24 | 0.93, 1.65 | 0.15 | 0.97 |
| Alcohol (g/day per year; 30 vs. 0) | 1.15 | 0.98, 1.34 | 0.082 | 1.08 | 0.90, 1.29 | 0.39 | 1.33 | 0.96, 1.85 | 0.088 | 0.28 |
| Aspirin use (tablets per week per year; 7 vs. 0) | 0.78 | 0.70, 0.86 | <0.0001 | 0.76 | 0.67, 0.86 | <0.0001 | 0.80 | 0.63, 1.01 | 0.060 | 0.76 |
| Endoscopic screening (yes vs. no; 20 years vs. 0)e | 0.74 | 0.67, 0.83 | <0.0001 | 0.82 | 0.73, 0.92 | 0.0005 | 0.48 | 0.36, 0.64 | <0.0001 | 0.0008 |
| PMH use (vs. never users) | ||||||||||
| Current use | 0.87 | 0.76, 0.98 | 0.026 | 0.88 | 0.76, 1.01 | 0.075 | 0.88 | 0.68, 1.15 | 0.35 | 0.97 |
| Past use | 0.93 | 0.83, 1.05 | 0.24 | 0.99 | 0.87, 1.13 | 0.89 | 0.79 | 0.61, 1.02 | 0.074 | 0.12 |
| Calcium intake (mg/day per year; 1,000 vs. 500) | 0.82 | 0.73, 0.91 | 0.0002 | 0.80 | 0.71, 0.91 | 0.0004 | 0.89 | 0.71, 1.13 | 0.36 | 0.43 |
Abbreviations: BMI, body mass index; CI, confidence interval; HR, hazard ratio; MET, metabolic equivalent; PMH, postmenopausal hormone.
a The total of colon cancers and rectal cancers does not equal the total of colorectal cancers due to some cases lacking a verified location.
b For variables whose β coefficients were calculated per year, the relative risk accounts for 40 years (e.g., ages 30–70 years) and for the specified contrast. Relative risk = exp[β (40 years) (contrast)]. For dichotomous variables, the relative risk was calculated as exp(β).
c Family history of colon or rectal cancer in a first-degree relative.
d BMI was calculated as weight (kg)/height (m)2.
e Sigmoidoscopy or colonoscopy.