Table 4.
Association between randomized vitamins E and C and risk of total cancer according to baseline characteristics, treatment assignment, and follow-up time in the Physicians’ Health Study II.a
| Group | Vitamin E | Vitamin C | ||||||
|---|---|---|---|---|---|---|---|---|
| No. of Total Cancer Events |
No. of Total Cancer Events |
|||||||
| Active | Placebo | Hazard Ratiob (95% CI) |
P Value for Interaction | Active | Placebo | Hazard Ratiob (95% CI) |
PValue for Interaction | |
| Age, years | 0.84 | 0.77 | ||||||
| 50–59 | 212c | 205 | 1.04 (0.86–1.26) | 205 | 212 | 0.96 (0.79–1.16) | ||
| 60–69 | 382 | 381 | 1.01 (0.87–1.16) | 388 | 375 | 1.05 (0.91–1.21) | ||
| ≥70 | 390 | 373 | 1.06 (0.92–1.22) | 380 | 383 | 1.00 (0.87–1.16) | ||
| Body mass index, kg/m2 | 0.44 | 0.56 | ||||||
| <25 | 420 | 396 | 1.05 (0.92–1.21) | 402 | 414 | 0.98 (0.86–1.13) | ||
| 25–29 | 449 | 470 | 0.99 (0.87–1.13) | 460 | 459 | 0.99 (0.87–1.13) | ||
| ≥30 | 114 | 92 | 1.20 (0.91–1.58) | 110 | 96 | 1.16 (0.88–1.52) | ||
| Smoking status | 0.82 | 0.15 | ||||||
| Never | 491 | 491 | 1.04 (0.91–1.17) | 506 | 476 | 1.08 (0.95–1.23) | ||
| Former | 451 | 424 | 1.03 (0.90–1.17) | 426 | 449 | 0.95 (0.83–1.08) | ||
| Current | 42 | 43 | 1.23 (0.80–1.88) | 40 | 45 | 0.76 (0.49–1.16) | ||
| Exercise ≥1 time/week | 0.44 | 0.15 | ||||||
| No | 401 | 374 | 1.10 (0.95–1.26) | 403 | 372 | 1.09 (0.94–1.25) | ||
| Yes | 569 | 562 | 1.02 (0.91–1.15) | 551 | 580 | 0.95 (0.84–1.07) | ||
| Alcohol consumption | 0.80 | 0.99 | ||||||
| Rarely/never | 806 | 790 | 1.03 (0.94–1.14) | 801 | 795 | 1.01 (0.92–1.11) | ||
| ≥1 drink/month | 173 | 163 | 1.07 (0.86–1.32) | 168 | 168 | 1.00 (0.81–1.24) | ||
| Current aspirin use | 0.31 | 0.70 | ||||||
| No | 218 | 198 | 1.14 (0.94–1.39) | 205 | 211 | 0.97 (0.80–1.18) | ||
| Yes | 758 | 749 | 1.02 (0.92–1.13) | 761 | 746 | 1.02 (0.92–1.13) | ||
| Parental history of cancerc | 0.88 | 0.20 | ||||||
| No | 357 | 347 | 1.04 (0.90–1.21) | 339 | 365 | 0.94 (0.81–1.09) | ||
| Yes | 473 | 463 | 1.03 (0.91–1.17) | 483 | 453 | 1.06 (0.93–1.21) | ||
| History of cancer | 0.42 | 0.17 | ||||||
| No | 895 | 882 | 1.03 (0.94–1.13) | 898 | 879 | 1.03 (0.94–1.13) | ||
| Yes | 89 | 77 | 1.14 (0.84–1.55) | 75 | 91 | 0.82 (0.61–1.12) | ||
| Randomized to vitamin C or Ed | 0.89 | 0.89 | ||||||
| Placebo | 491 | 479 | 1.03 (0.91–1.17) | 480 | 479 | 1.00 (0.88–1.14) | ||
| Active | 493 | 480 | 1.05 (0.92–1.19) | 493 | 491 | 1.01 (0.89–1.15) | ||
| Period of follow-up | 0.53 | 0.43 | ||||||
| <4 years | 437 | 444 | 1.01 (0.89–1.16) | 443 | 438 | 0.96 (0.84–1.10) | ||
| ≥4 years | 547 | 515 | 1.08 (0.95–1.21) | 530 | 532 | 1.01 (0.89–1.13) | ||
Abbreviations: CI, confidence interval; HR, hazard ratio.
a
Mean follow-up of 8.0 years for all 14,641 men through August 31, 2007.
b
Adjusted for age, PHS cohort (original PHS I participant, new PHS participant), and randomized treatment assignment (beta-carotene, multivitamin, and either vitamin E or vitamin C).
c
Excludes 2,083 men with missing information on parental history of cancer.
d
For analyses of vitamin E, stratified by vitamin C; for analyses of vitamin C, stratified by vitamin E.