TABLE 3.
HRs for colorectal cancer by tea intake in the NIH-AARP Diet and Health Study1
| All tea | Caffeinated tea | Decaffeinated tea | ||||
| Outcome | No. of cases | HR (95% CI) | No. of cases | HR (95% CI) | No. of cases | HR (95% CI) |
| Colorectal | 6905 | — | 6905 | — | 6905 | — |
| None | 2322 | 1.00 | 3853 | 1.00 | 5762 | 1.00 |
| <1 cup/mo | 1236 | 0.90 (0.84, 0.97) | 794 | 0.91 (0.84, 0.99) | 209 | 0.92 (0.80, 1.06) |
| 1–3 cups/mo | 1143 | 0.95 (0.88, 1.02) | 799 | 0.96 (0.89, 1.04) | 279 | 0.95 (0.84, 1.07) |
| 1–6 cups/wk | 1144 | 0.93 (0.86, 1.00) | 767 | 0.99 (0.91, 1.08) | 332 | 0.82 (0.73, 0.92) |
| ≥1 cup/d | 1060 | 0.97 (0.90, 1.05) | 692 | 1.00 (0.91, 1.09) | 323 | 0.93 (0.83, 1.05) |
| P-trend | — | 0.700 | — | 0.300 | — | 0.300 |
| Colon | 5044 | — | 5044 | — | 5044 | — |
| None | 1666 | 1.00 | 2829 | 1.00 | 4164 | 1.00 |
| <1 cup/mo | 906 | 0.91 (0.84, 0.99) | 578 | 0.92 (0.84, 1.01) | 162 | 0.98 (0.83, 1.15) |
| 1–3 cups/mo | 843 | 0.96 (0.89, 1.05) | 578 | 0.96 (0.87, 1.06) | 216 | 1.00 (0.87, 1.16) |
| 1–6 cups/wk | 841 | 0.94 (0.86, 1.02) | 551 | 0.98 (0.89, 1.08) | 257 | 0.86 (0.76, 0.99) |
| ≥1 cup/d | 788 | 0.99 (0.91, 1.08) | 508 | 1.01 (0.91, 1.11) | 245 | 0.96 (0.84, 1.11) |
| P-trend | — | 0.500 | — | 0.400 | — | 0.700 |
| Proximal colon | 2846 | — | 2846 | — | 2846 | — |
| None | 931 | 1.00 | 1579 | 1.00 | 2347 | 1.00 |
| <1 cup/mo | 512 | 0.90 (0.81, 1.01) | 330 | 0.93 (0.82, 1.05) | 94 | 0.96 (0.77, 1.19) |
| 1–3 cups/mo | 473 | 0.94 (0.84, 1.05) | 317 | 0.92 (0.81, 1.05) | 125 | 0.98 (0.81, 1.19) |
| 1–6 cups/wk | 473 | 0.90 (0.80, 1.01) | 304 | 0.94 (0.82, 1.07) | 156 | 0.88 (0.74, 1.04) |
| ≥1 cup/d | 457 | 0.98 (0.88, 1.10) | 316 | 1.08 (0.95, 1.23) | 124 | 0.81 (0.67, 0.98) |
| P-trend | — | 0.600 | — | 0.080 | — | 0.060 |
| Distal colon | 1983 | — | 1983 | — | 1983 | — |
| None | 656 | 1.00 | 1125 | 1.00 | 1638 | 1.00 |
| <1 cup/mo | 363 | 0.95 (0.83, 1.08) | 227 | 0.93 (0.80, 1.08) | 62 | 1.01 (0.78, 1.32) |
| 1–3 cups/mo | 333 | 1.00 (0.87, 1.14) | 234 | 1.01 (0.87, 1.17) | 82 | 1.03 (0.82, 1.30) |
| 1–6 cups/wk | 331 | 0.98 (0.86, 1.12) | 226 | 1.05 (0.90, 1.23) | 87 | 0.80 (0.64, 1.01) |
| ≥1 cup/d | 300 | 1.02 (0.88, 1.17) | 171 | 0.90 (0.76, 1.07) | 114 | 1.24 (1.01, 1.52) |
| P-trend | — | 0.600 | — | 0.400 | — | 0.050 |
| Rectal | 1861 | — | 1861 | — | 1861 | — |
| None | 656 | 1.00 | 1024 | 1.00 | 1598 | 1.00 |
| <1 cup/mo | 330 | 0.87 (0.76, 1.00) | 216 | 0.89 (0.77, 1.04) | 47 | 0.76 (0.57, 1.03) |
| 1–3 cups/mo | 300 | 0.91 (0.79, 1.05) | 221 | 0.97 (0.83, 1.13) | 63 | 0.79 (0.61, 1.03) |
| 1–6 cups/wk | 303 | 0.91 (0.79, 1.05) | 216 | 1.02 (0.88, 1.20) | 75 | 0.69 (0.54, 0.88) |
| ≥1 cup/d | 272 | 0.92 (0.80, 1.07) | 184 | 0.97 (0.82, 1.14) | 78 | 0.84 (0.66, 1.07) |
| P-trend | — | 0.800 | — | 0.600 | — | 0.200 |
HRs and 95% CIs were estimated by using Cox proportional hazards regression models with person-years as the underlying time metric adjusted for age (continuous), sex, race (non-Hispanic white, non-Hispanic black, Hispanic/Asian/Pacific Islander/American Indian/Alaskan native, or unknown), education (<11 y or unknown, high school graduate, some college, or college graduate), smoking status (never, former, or current), time since quitting for former smokers, smoking dose, ever smoke a pipe or cigar, diabetes (yes or no), colorectal screening (yes or no), family history of colorectal cancer (yes or no), regular nonsteroidal antiinflammatory drug use (yes or no), marital status (married: yes or no), BMI (in kg/m2; <18.5, 18.5 to <25, 25 to <30, 30 to <35, or ≥35), frequency of vigorous physical activity (never or rarely, 1–3 times/mo, or 1–2, 3–4, or ≥5 times/wk), calories (continuous), fruit and vegetables (continuous), red meat (continuous), dietary calcium intake (continuous), alcohol (continuous), and menopausal hormone therapy in women (yes or no). P values for linear trends were calculated by using median values within quintiles. All statistical tests were 2-sided and considered significant at P < 0.05; analyses were conducted with SAS software (version 9.1.3; SAS Institute).