Table 2.
Multivariable relative risk* of colorectal cancer according to frequency of bowel movement in the Nurses’ Health Study (1982-2010) and in the Health Professionals Follow-up Study (2000-2010)
| The Nurses’ Health Study | Frequency of bowel movement
|
P for trend | |||
|---|---|---|---|---|---|
| >1/day | daily | every 2 days | every 3 days or less | ||
| Colorectal cancer (n=1737) | 169 | 1155 | 294 | 119 | |
| 0.86 (0.73,1.01) | 1.0 (Reference) | 0.99 (0.87,1.13) | 0.86 (0.71,1.04) | 0.43 | |
| Colon cancer (n=1374) | 140 | 892 | 251 | 91 | |
| 0.92 (0.77,1.11) | 1.0 (Reference) | 1.11 (0.96,1.27) | 0.86 (0.69,1.07) | 0.43 | |
| Proximal colon cancer (n=822) | 86 | 536 | 142 | 58 | |
| 0.96 (0.76,1.21) | 1.0 (Reference) | 1.05 (0.87,1.26) | 0.92 (0.70,1.21) | 0.80 | |
| Distal colon cancer (n=513) | 48 | 333 | 102 | 30 | |
| 0.82 (0.61,1.12) | 1.0 (Reference) | 1.20 (0.96,1.50) | 0.74 (0.51,1.08) | 0.25 | |
| Rectal cancer (n=363) | 29 | 263 | 43 | 28 | |
| 0.63 (0.43,0.93) | 1.0 (Reference) | 0.62 (0.45,0.85) | 0.86 (0.58,1.27) | 0.83 | |
|
| |||||
| The Health Professionals Follow-up Study | >1/day | daily | every 2 days or less | P for trend | |
|
| |||||
| Colorectal cancer (n=275) | 67 | 192 | 16 | 0.91 | |
| 0.97 (0.73,1.29) | 1.0 (Reference) | 0.81 (0.48,1.37) | |||
| Colon cancer (n=205) | 43 | 149 | 13 | 0.28 | |
| 0.79 (0.55,1.11) | 1.0 (Reference) | 0.84 (0.47,1.51) | |||
| Proximal colon cancer (n=91) | 16 | 69 | 6 | 0.32 | |
| 0.70 (0.40,1.21) | 1.0 (Reference) | 0.77 (0.32,1.85) | |||
| Distal colon cancer (n=72) | 19 | 48 | 5 | 0.73 | |
| 1.10 (0.63,1.92) | 1.0 (Reference) | 0.98 (0.38,2.58) | |||
| Rectal cancer (n=70) | 24 | 43 | 3 | 0.06 | |
| 1.58 (0.92,2.70) | 1.0 (Reference) | 0.70 (0.21,2.35) | |||
Adjusted for age (in months), smoking before age 30 (0, 1-4, 5-10, or >10 pack-years), history of colorectal cancer in a parent or sibling (yes, no), history of endoscopy (yes, no), regular aspirin use (yes, no), body mass index (<25, 25–<30, ≥30 kg/m2), physical activity (< 3, 3–<27, ≥ 27 MET-hrs/wk), postmenopausal hormone use (premenopausal, never, past, or current user, women only), consumption of processed meat (quintiles), alcohol consumption (0–<5, 5–<10, 10–<15, or ≥15 g/d), energy-adjusted total calcium intake (quintiles), total folate (quintiles), total fiber (quintiles), total vitamin D intake (quintiles), and total energy intake (quintiles).