Table 4.
Hazard ratios for liver cancer by quartiles of selected vitamin intakes in the Shanghai Women’s (1997–2000) and Men’s (2002–2006) Health Studies, stratified by self-reported liver disease and/or family history of liver cancer
| Vitamin intakes* | Participants without self-reported liver disease and family history of liver cancer (n=176) | Participants with self-reported liver disease or family history of liver cancer (n=91) | P interaction‡ | ||
| No. of cancers | HR (95% CI)† | No. of cancers | HR (95% CI)† | ||
| Vitamin E, mg/d§ | .84 | ||||
| ≤9.977 (10.531) | 59 | 1.00 (reference) | 23 | 1.00 (reference) | |
| ≤12.785 (13.877) | 41 | 0.74 (0.49 to 1.11) | 24 | 0.95 (0.53 to 1.69) | |
| ≤16.176 (17.937) | 37 | 0.64 (0.42 to 1.00) | 20 | 0.69 (0.37 to 1.28) | |
| >16.176 (17.937) | 39 | 0.58 (0.35 to 0.95) | 24 | 0.64 (0.33 to 1.23) | |
| P trend | .02 | .12 | |||
| Vitamin E, mg/d§,‖ | .54 | ||||
| ≤9.977 (10.531) | 54 | 1.00 (reference) | 17 | 1.00 (reference) | |
| ≤12.785 (13.877) | 37 | 0.75 (0.49 to 1.15) | 9 | 0.51 (0.23 to 1.15) | |
| ≤16.176 (17.937) | 31 | 0.62 (0.39 to 0.99) | 11 | 0.54 (0.25 to 1.18) | |
| >16.176 (17.937) | 30 | 0.52 (0.30 to 0.88) | 15 | 0.67 (0.31 to 1.42) | |
| P trend | .01 | .32 | |||
| Vitamin E supplement use§ | .19 | ||||
| No | 168 | 1.00 (reference) | 82 | 1.00 (reference) | |
| Yes | 8 | 0.50 (0.23 to 1.10) | 9 | 0.59 (0.27 to 1.28) | |
| Vitamin C supplement use§ | .01 | ||||
| No | 165 | 1.00 (reference) | 70 | 1.00 (reference) | |
| Yes | 11 | 1.21 (0.61 to 2.37) | 21 | 3.39 (1.94 to 5.92) | |
| Multivitamin supplement use in men | .06 | ||||
| No | 79 | 1.00 (reference) | 49 | 1.00 (reference) | |
| Yes | 7 | 1.28 (0.58 to 2.84) | 14 | 2.64 (1.40 to 4.99) | |
* Cut points for the quartiles of vitamin intakes used in analyses of data from the Shanghai Women’s Health Study along with the cut points for the Shanghai Men’s Health Study are shown in parentheses. In analyses of data from women and men combined, dietary intake variables were categorized on the basis of sex-specific quartile distributions.
† The hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated by using Cox proportional hazard models with adjustment for age (y, continuous variable), body mass index (kg/m2, continuous variable), fat intake (g/d, continuous variable), family income level (low, medium, and high), education level (elementary school or less, middle school, high school, college or above), history of diabetes (yes or no), history of cholelithiasis or cholecystectomy (yes or no), and mutually adjusted for vitamin E intake (cut points for the quartiles of vitamin E intake in the SWHS were ≤9.977, ≤12.785, ≤16.176, and >16.176 and in the SMHS were ≤10.531, ≤13.877, ≤17.937, and >17.937), vitamin E supplement (yes or no), vitamin C supplement (yes or no), and multivitamin supplement use (yes or no). P trend was calculated by assigning an ordinal value (1, 2, 3, 4) to each quartile (Q1, Q2, Q3, and Q4) of exposure and treating it as a continuous variable in the regression models.
‡ P interaction was calculated by introducing an interaction term between the exposure and self-reported liver disease and/or family history of liver cancer in the regression model. All P values were two-sided.
§ The HRs and 95% CIs were calculated by using Cox proportional hazard models with adjustment for sex (male or female), age (y, continuous variable), body mass index (kg/m2, continuous variable), fat intake (g/d, continuous variable), family income level (low, medium, and high), education level (elementary school or less, middle school, high school, college or above), history of diabetes (yes or no), history of cholelithiasis or cholecystectomy (yes or no), and mutually adjusted for vitamin E intake (cut points for the quartiles of vitamin E intake in the SWHS were ≤9.977, ≤12.785, ≤16.176, and >16.176 and in the SMHS were ≤10.531, ≤13.877, ≤17.937, and >17.937), vitamin E supplement (yes or no), vitamin C supplement (yes or no), and multivitamin supplement use (yes or no).
‖ Individuals who had used any vitamin supplement before enrollment were excluded from the analysis.