Journal of the National Cancer Institute Advance Access published online on August 8, 2007
JNCI Journal of the National Cancer Institute, doi:10.1093/jnci/djm084
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Published by Oxford University Press 2007.
ARTICLES |
Chemoprevention of Primary Liver Cancer: A Randomized, Double-Blind Trial in Linxian, China
Affiliations of authors: Cancer Institute, Chinese Academy of Medical Sciences, Beijing, China (CXQ, JHF, XDS, YLQ); Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD (FK, PRT, BEC, CCA, SMD); Information Management Services, Silver Spring, MD (BY); Department of Preventive Medicine and Biometrics, University of Colorado Health Sciences Center, Denver, CO (SDM)
Correspondence to: Farin Kamangar, MD, PhD, Division of Cancer Epidemiology and Genetics, National Cancer Institute, 6120 Executive Blvd, Rm 3034, Bethesda, MD 10892-7232 (e-mail: kamangaf{at}mail.nih.gov) or You-Lin Qiao, MD, PhD, Department of Cancer Epidemiology, Cancer Institute, Chinese Academy of Medical Sciences, PO Box 2258, Beijing 100021, People’s Republic of China (e-mail: qiaoy{at}public.bta.net.cn).
 |
ABSTRACT |
|---|
 Top Abstract Context and CaveatsSubjects and MethodsResultsDiscussionFundingReferencesNotes |
|---|
Background: Primary liver cancer is a common malignancy with a dismal prognosis. New primary prevention strategies are needed to reduce mortality from this disease. We examined the effects of supplementation with four different combinations of vitamins and minerals on primary liver cancer mortality among 29450 initially healthy adults from Linxian, China.
Methods: Participants were randomly assigned to take either a vitamin–mineral combination ("factor") or a placebo daily for 5.25 years (March 1986–May 1991). Four factors (at doses one to two times the US Recommended Daily Allowance)—retinol and zinc (factor A); riboflavin and niacin (factor B); ascorbic acid and molybdenum (factor C); and beta-carotene, alpha-tocopherol, and selenium (factor D)—were tested in a partial factorial design. The study outcome was primary liver cancer death occurring from 1986 through 2001. Adjusted Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) of liver cancer death with and without each factor. All P values are two-sided.
Results: A total of 151 liver cancer deaths occurred during the analysis period. No statistically significant differences in liver cancer mortality were found comparing the presence and absence of any of the four intervention factors. However, both factor A and factor B reduced liver cancer mortality in individuals younger than 55 years at randomization (HR = 0.59, 95% CI = 0.34 to 1.00, and HR = 0.54, 95% CI = 0.31 to 0.93, respectively) but not in older individuals (HR = 1.06, 95% CI = 0.71 to 1.59, and HR = 1.12, 95% CI = 0.75 to 1.68, respectively). Factor C reduced liver cancer death, albeit with only borderline statistical significance in males (HR = 0.70, 95% CI = 0.47 to 1.02) but not in females (HR = 1.30, 95% CI = 0.72 to 2.37). Cumulative risks of liver cancer death were 6.0 per 1000 in the placebo arm, 5.4 per 1000 in the arms with two factors, and 2.4 per 1000 in the arm with all four factors.
Conclusion: None of the factors tested reduced overall liver cancer mortality. However, three factors reduced liver cancer mortality in certain subgroups.
Prior knowledge Liver cancer is relatively common, and the death rate from the disease is high. Several possible chemoprevention strategies are being investigated, including nutritional chemoprevention. Study design The Linxian General Population Trial was a randomized factorial intervention trial that examined the effects of four vitamin–mineral combinations ("factors"), taken for 5.25 years, on incidence of and mortality from several cancers in a Chinese population with inadequate intake of multiple vitamins and minerals. Follow-up (an average of nearly 13 years) is now sufficient to examine liver cancer mortality. Contribution None of the factors reduced mortality from liver cancer overall. However, some factors reduced liver cancer mortality in subgroups defined by age or sex. Implications In populations with poor nutrition, certain subgroups may experience reduced liver cancer mortality if they take certain nutritional supplements. Limitations Some of the results, including the subgroup findings, may have arisen by chance. Because each intervention factor was a combination of several vitamins and minerals, it was not possible to evaluate the independent effect of each vitamin or mineral. The population of Linxian may not be representative of other populations, especially vitamin-replete populations.
|
With approximately 626000 new cancer cases and 598000 deaths worldwide per year, liver cancer is the sixth most common incident cancer and the third most common cause of cancer death (1,2). Liver cancer is especially common in certain areas of sub-Saharan Africa and East Asia (3). Rates are lower in the United States and most other developed countries. However, in the past 30 years, incidence has nearly doubled in many countries (2,4,5), including the United States, presumably as a result of increases in the prevalence of hepatitis C virus (HCV) infections that occurred in the late 1960s and early 1970s, associated with increased injection drug use at the time (4,5).
The major risk factors for liver carcinogenesis include hepatitis B virus (HBV) infection, HCV infection, aflatoxin exposure, and alcohol consumption (3–6), with interactions between hepatitis viruses and aflatoxins responsible for the majority of cases worldwide (7). The dismal prognosis of liver cancer (1,2) implies that primary prevention should be considered the major method of controlling death from this disease. Primary prevention via HBV vaccination of newborns has already been undertaken in more than 150 countries worldwide (8), and this strategy has been shown to reduce the risk of liver cancer (9). Unfortunately, similar vaccines for HCV prevention do not exist, and many people are already infected with HBV. For these latter groups, chemoprevention may reduce their risk of liver cancer. Chemoprevention using oltipraz and chlorophyllin, chemical agents that detoxify or impede the bioavailability of aflatoxin, has shown promise (7,10), but definitive results are not yet available. Chemoprevention of liver cancer using vitamins and minerals is also of interest (11).
The people of Linxian, China, suffer from moderately high rates of liver cancer incidence and death, with a death rate of 40 per 100000 person-years in the Linxian General Population Trial cohort. After esophageal and gastric cancers, liver cancer is the third most common cause of cancer death in this area. Previous studies have also documented inadequate intake of multiple vitamins and minerals in this population (12,13). The Linxian General Population Trial was a randomized intervention trial that was designed to examine the effects of four combinations of vitamins and minerals ("factors") in reducing esophageal and gastric cancer incidence and mortality in Linxian (14). Factor A consisted of retinol (5000 IU, as retinol palmitate) and zinc (22.5 mg, as zinc oxide); zinc facilitates the delivery of retinol to tissues. Factor B consisted of the B vitamins riboflavin (3.2 mg) and niacin (40 mg). Factor C consisted of ascorbic acid (120 mg) and molybdenum (30 µg, as molybdenum yeast complex), both of which inhibit the formation of nitrosamines. Factor D consisted of beta-carotene (15 mg), alpha-tocopherol (30 mg), and selenium (50 µg, as selenium yeast); these are antioxidants. Doses ranged from one to two times the US Recommended Daily Allowances. Data from the Linxian trial, which took place from 1986 to 1991, found that factor D had no statistically significant effect on esophageal cancer incidence or mortality but reduced gastric cancer incidence and mortality (14,15). Smaller numbers of cases limited the power of similar assessments for other cancers. However, an extended follow-up through 2001 now permits evaluation of the effects of these micronutrient combinations on liver cancer deaths. In addition to the main effects, we also investigated interactions with sex, age, smoking, alcohol drinking, and HBV status.
|
Subjects and Methods |
|---|
|
TopAbstractContext and CaveatsSubjects and MethodsResultsDiscussionFundingReferencesNotes |
|---|
Design of the Trial and Post-trial Follow-up
The detailed design and conduct of the Linxian General Population Trial and its extended follow-up have been described elsewhere (14,16). Participants were recruited in 1985 from Yaocun, Rencun, Donggang, and Hengshui communes in Linxian, a rural county in Henan Province. Residents 40–69 years of age with no history of cancer or debilitating diseases were eligible for this trial and were invited to enroll. These individuals were interviewed for personal medical history, family history of cancer, diet, and alcohol and tobacco consumption; were given a brief medical exam; and had a 10-mL blood sample collected. Of the 43956 initially eligible subjects, 30283 were randomly assigned to an intervention arm. Reasons for exclusion have been described in previous publications (14,17). Of these subjects, 699 subjects were diagnosed with cancer or died before the intervention began and were excluded. Therefore, 29584 participants received any treatment, of whom 134 were excluded from this analysis because they were lost to follow-up before the study began or because of lack of data on age, sex, smoking, or drinking status. Therefore, this analysis was conducted on 29450 subjects (Fig. 1).
|
In accord with a 24 partial factorial design, participants were randomly assigned to eight intervention groups (treatment arms), which were defined by the following combinations of factors: AB, AC, AD, BC, BD, CD, ABCD, or placebo. Therefore, out of each eight participants, approximately one (12.5%) received placebo, six (75%) received a combination of two factors, and one (12.5%) received all four factors. With this design, approximately half of the subjects received and half did not receive each factor (e.g., half received factor A and half did not).
Supplements were distributed from March 1986 through May 1991 (5.25 years). The results of a pilot study (18,19) showed excellent participation rates and compliance for taking pills in this population. During the trial period, village doctors visited the study subjects every month, delivered the pills to participants in person, and collected and counted the number of residual pills from the previous month. The overall pill disappearance rate was 93%, with no differences by treatment arm (range = 92%–93%). Compliance was also assessed by quarterly collection and analysis of blood samples. In each quarterly survey, nine villages were selected at random, followed by random selection of 36 individuals from each village, who were apportioned within strata defined by age (<50, 50–59, 
60 years) and sex. Blood was analyzed for retinol, beta-carotene, and ascorbic acid and for the glutathione reductase activation coefficient as a measure of riboflavin status. At baseline, biochemical measures of the nutrients showed no difference among individuals assigned to the various treatment arms, but during the trial period, all values were consistently statistically significantly different between treated and untreated individuals (all P values 
.0001) (14,17).
Throughout the trial period, village health workers recorded cancer incidence and mortality data at monthly intervals. An independent three-person Data and Safety Monitoring Committee met periodically throughout the trial to review progress and make recommendations. Diagnostic materials (pathology and cytology slides, X-rays, and clinical records) for 85% of the cancer cases in this study were reviewed by a panel of American and Chinese experts. In the 10 years after the active intervention period, study subjects were contacted monthly by village health workers or study interviewers to check on vital status and ask about cancer diagnosis. For those with a diagnosis of any cancer, diagnostic materials were collected, and the cancer diagnoses were verified by senior Chinese diagnosticians from Beijing. Case ascertainment is considered to be essentially complete, and exclusion and loss to follow-up are minimal. Outcomes for this study were based on follow-up data from March 1986 through May 2001.
The conduct of the Linxian General Population Trial was approved by the institutional review boards of the Cancer Institute of Chinese Academy of Medical Sciences and the US National Cancer Institute, and written informed consent was obtained from all study subjects.
Serum Antibody Assays
In a previous study of dichloro-diphenyl-trichloroethane (DDT) and liver cancer in the Linxian General Population Trial cohort (20), baseline serum samples from the liver cancer case subjects and from two or three control subjects per case subject (frequency matched on age and sex) were assayed for markers of exposure to HBV and HCV. After excluding subjects with no serum available, data were obtained for 141 subjects who died of liver cancer and 342 control subjects. Hepatitis B surface antigen (HBsAg) was analyzed using the Bio-Rad Genetic Systems HBsAg enzyme immunoassay kit of Bio-Rad Laboratories, Hercules, CA. Antibody to hepatitis B core antigen (anti-HBc) was analyzed using the HBc (recombinant) ORTHO ELISA Test Systems of Ortho-Clinical Diagnostics, Raritan, NJ. Antibody to HCV (anti-HCV) was analyzed using the ORTHO HCV ELISA Test Systems assay of Ortho-Clinical Diagnostics.
Statistical Methods
We tabulated frequencies and percentages of age groups, sex, smoking status, alcohol consumption history, and serum markers of HBV and HCV exposure for all subjects by treatment arm. Smoking status was defined as a dichotomous variable, never versus ever smoking (defined as smoking regularly for at least 6 months). Because alcohol drinking was uncommon in this population (21), alcohol consumption was also defined as a dichotomous variable, none versus any drinking in the past 12 months. Furthermore, because in Linxian cigarette smoking and alcohol consumption rates were very low among women (<1% of women smoked and only 10% of women reported any drinking in the past 12 months), we limited analyses related to smoking and alcohol drinking to male participants.
We conducted two sets of analyses to examine whether the intervention factors reduced liver cancer deaths. First, we compared risk (either cumulative or hazards) between those who received each factor and those who did not. For example, for factor A, we compared outcomes in all groups that received factor A (AB, AC, AD, and ABCD) with those in all groups that did not receive factor A (BC, BD, CD, and placebo). In the analysis of factorial trials, this kind of analysis is known as "at-the-margins analysis" (22) and has the most power to examine the effect of each factor. At-the-margins analysis is most appropriate when there is no statistical interaction between the factors. Second, we compared outcomes in each of the seven treatment arms (AB, AC, AD, BC, BD, CD, and ABCD) with those in the placebo-only arm as the referent group. This kind of analysis, known as "inside-the-table" analysis (22), is less powerful than at-the-margins analysis but is useful when there is evidence for interaction between the factors.
For the at-the-margins analysis, the competing risks method described by Gray (23) was used to calculate cumulative risks. Cumulative incidence curves were plotted, and Gray tests (23) were used to compare time to liver cancer death between those who did and those who did not receive each factor. We also used Cox proportional hazards models to compare liver cancer deaths with each treatment factor, adjusting for other treatments, sex, age (<55 versus 55 years, the midpoint of age in this cohort), and residence area (commune). Hazard ratios (HRs) of liver cancer mortality and 95% confidence intervals (CIs) were calculated for each of the factors. Departures from multiplicative models (i.e., multiplicative interactions) between each of the factors and age, sex, smoking, alcohol consumption, and serum HBsAg status were examined by including appropriate terms in the Cox models. As with other analyses of this trial (24,25), tests of the interaction between each factor and age and sex were planned a priori. However, tests of the interaction between each factor and smoking, alcohol, and HBsAg were secondary analyses, and the results of these analyses need to be considered with appropriate caution.
For the inside-the-table analysis, we used Cox regression models to compare outcomes in each treatment arm versus the placebo-only arm. Hazard ratios for liver cancer death and 95% confidence intervals adjusted for other treatments, sex, age, and residence area are presented for each of these comparisons.
Finally, in the subgroup of case and control patients for whom data on HBsAg status were available, further adjustment was done in both sets of analyses by including HBsAg in the models. Including HBsAg did not materially modify any of the results. The assumption of proportionality was verified for all of the analyses by plotting the difference in log cumulative hazard rates versus time and by using models that allowed calculation of time-dependent risk ratios. All P values are two-sided, and for all analyses (both main effects and interaction analyses), P values less than .05 were considered as statistically significant.
Power Calculation
Approximately half of the trial subjects (range = 14714–14740) received and the other half did not receive each of the factors. Approximately 82 liver cancer deaths (range = 81–83) were reported among participants who were in the referent group for each factor analysis. For a two-sided 
= .05, these numbers provided at least 82% power to detect a risk ratio of 0.6 or less or 1.5 or more.
|
Results |
|---|
|
TopAbstractContext and CaveatsSubjects and MethodsResultsDiscussionFundingReferencesNotes |
|---|
From March 1986 through May 2001, there were a total of 380648 person-years of follow-up. The mean and median follow-up times were 12.9 and 15.2 years, respectively. A total of 9688 deaths occurred in the cohort, with the most common causes of death being stroke, esophageal cancer, and gastric cancer. During the follow-up period, a total of 161 incident liver cancer cases and 151 liver cancer deaths were reported in the cohort. Because analyses by incident liver cancer yielded essentially the same results as analyses by liver cancer death, we report only results for liver cancer death.
Table 1 shows the demographic characteristics, smoking and alcohol consumption rates, and markers of HBV and HCV exposure in all study subjects and as a range across study arms. Variables for which data were available for the entire cohort (age group, sex, smoking, and drinking) were distributed uniformly among the eight study arms, which shows the success of the randomization method.
|
Main Effects for Factors A–D
Figure 2 shows the cumulative liver cancer mortality curves for those receiving each of the four vitamin–mineral factors. The dashed vertical lines demarcate the trial period and each of the two 5-year post-trial follow-up periods. No statistically significant associations were observed; Gray test P values were .28 for factor A, .36 for factor B, .28 for factor C, and .22 for factor D. The hazard ratios for death from liver cancer from Cox models (adjusted for sex, age group, commune, and the other vitamin–mineral treatments) were 0.86 (95% CI = 0.62 to 1.18) for factor A, 0.86 (95% CI = 0.62 to 1.18) for factor B, 0.84 (95% CI = 0.61 to 1.16) for factor C, and 0.81 (95% CI = 0.59 to 1.12) for factor D (Table 2). Adding HBsAg status to the models did not statistically significantly or materially modify the results (Table 2).
|
|
Interactions Between Factors A–D and Other Risk Factors
There was a borderline statistically significant effect modification by age for factor A (Pinteraction = .09) and a statistically significant effect modification by age for factor B (Pinteraction = .02). Specifically, factor A protected against liver cancer mortality for study participants who were younger than 55 years of age at baseline (HR = 0.59, 95% CI = 0.34 to 1.00) but not for study participants who were 55 years or older (HR = 1.06, 95% CI = 0.71 to 1.59). Likewise, factor B was protective against liver cancer mortality for study participants who were less than 55 years of age at baseline (HR = 0.54, 95% CI = 0.31 to 0.93) but not for study participants who were 55 years or older (HR = 1.12, 95% CI = 0.75 to 1.68). There were no statistically significant interactions between age and factors C or D.
There was a borderline statistically significant effect modification by sex for factor C (Pinteraction = .08) but no interactions between sex and any of the other factors. In addition, factor C showed a close-to-statistically significant (P = .058) protection against liver cancer for men (HR = 0.70, 95% CI = 0.47 to 1.02) but not for women (HR = 1.30, 95% CI = 0.72 to 2.37).
Analyses of interactions with tobacco smoking and alcohol drinking were limited to males. Tobacco smoking did not modify the effect of any of the four factors on liver cancer mortality; all P values for interaction were greater than .24. Alcohol consumption modified the effect of factor D on liver cancer mortality (Pinteraction = .03) but did not modify the effect of factors A, B, or C (Pinteraction>.17). Factor D was associated with a non–statistically significantly increased risk of liver cancer mortality among alcohol drinkers (HR = 1.61, 95% CI = 0.85 to 3.08) and a non–statistically significantly reduced risk among nondrinkers (HR = 0.64, 95% CI = 0.40 to 1.05). There were no statistically significant interactions between serum HBsAg status and any of the factors; all P values for interaction were more than .49.
Main Effects by Treatment Arms
There were approximately 3680 subjects in each treatment arm (range = 3674–3695) (Table 2). In the placebo group, 22 liver cancer deaths were identified (cumulative risk = 6.0 per 1000). By comparison, among the 22091 participants randomly assigned to an arm with two factors, 120 died of liver cancer (cumulative risk = 5.4 per 1000). Cumulative risks in treatment arms with two factors ranged from 4.9 per 1000 to 6.3 per 1000, and the adjusted relative hazard ratios of liver cancer mortality relative to the placebo-only group ranged from 0.80 to 1.06; 95% confidence intervals for all of these hazard ratios included 1.0. Cumulative death rates and hazard ratios were statistically significantly lower in the treatment arm that received all four factors than in the placebo arm; only nine of the 3685 participants in this treatment arm died of liver cancer (cumulative risk = 2.4 per 1000), and the hazard ratio was statistically significantly less than 1.0 (HR = 0.41, 95% CI = 0.19 to 0.88).
|
Discussion |
|---|
|
TopAbstractContext and CaveatsSubjects and MethodsResultsDiscussionFundingReferencesNotes |
|---|
Liver cancer is the leading cause of cancer death in certain areas of China, such as Qidong County in Jiangsu Province (26). In Linxian, where the current study was conducted, liver cancer is also moderately common and is the third most common cause of cancer death. In this study, we investigated the effects of four combinations of vitamins and minerals (factors A, B, C, and D) in preventing death from primary liver cancer in Linxian.
In our study, supplementation with retinol and zinc (factor A) did not have a statistically significant effect on liver cancer mortality. However, it had a borderline statistically significant interaction with age and statistically significantly protected against liver cancer mortality in younger (<55 years old) participants. To our knowledge, this is the first report of an intervention trial using retinol or zinc to prevent liver cancer mortality. At least two prospective studies have shown an inverse association between prediagnostic levels of serum retinol and future risk of liver cancer (11,27). However, liver is the major storage site of vitamin A in the body, and chronic liver disease results in lower levels of circulating retinol. Therefore, a reverse causal association cannot be ruled out with observational studies, and more definitive evidence needs interventional studies (11,27). A trial that examined the effects of a combination of beta-carotene and retinol in reducing lung cancer risk (28) did not report results for liver cancer, presumably because the numbers were low; only nine liver cancer cases were diagnosed (four in the treatment group and five in the placebo group), as reported in a subsequent meta-analysis by Bjelakovic et al. (29). In a randomized trial, Muto et al. (30) found a statistically significant effect of polyprenoic acid, an acyclic retinoid, in preventing the recurrence of second primary tumors of the liver. However, to our knowledge, polyprenoic acid has not been studied in primary prevention of liver cancer. In addition, there are no previous reports of zinc supplementation and liver cancer.
To our knowledge, no previous trial has examined the effects of supplementation with riboflavin or niacin on liver cancer. We did not find an overall statistically significant effect of riboflavin and niacin (factor B) on liver cancer death. However, age statistically significantly modified the effect of factor B on liver cancer deaths, and factor B statistically significantly reduced deaths in younger but not older participants. Large amounts of riboflavin have been reported to non–statistically significantly reduce the development of aflatoxin-induced liver cancer in female Wistar rats (31). Niacin suppresses proliferation and invasion of cultured hepatoma cell lines (32).
Supplementation with molybdenum and vitamin C (factor C) did not have a statistically significant effect on liver cancer risk, and there was no interaction with age. However, it reduced risk to a nearly statistically significant degree in men but not in women, and the P for interaction by sex was statistically significant. One other study has examined vitamin C and liver cancer deaths. The MRC/BHF Heart Protection Study (33) randomly assigned 20536 UK adults to receive a combination of vitamin C (ascorbic acid), vitamin E (alpha-tocopherol), and beta-carotene versus placebo. Only 12 liver cancer cases were diagnosed in this trial (seven in the antioxidant group and five in the placebo group), as reported in the meta-analysis of Bjelakovic et al. (29). To our knowledge, no other study has examined the association between molybdenum and liver cancer.
We also found that beta-carotene, alpha-tocopherol, and selenium (factor D) were not statistically significantly associated with risk of liver cancer death. Among males, however, alcohol consumption statistically significantly modified the effect of factor D on liver cancer mortality. Effects of components of factor D on liver cancer risk have been studied in both animals and humans. Several studies in Jiangsu Province, China, showed a protective effect of selenium against this cancer. In these studies, there was an inverse correlation between the geographic distribution of liver cancer incidence and the selenium contents of whole blood and grains (34). Animal experiments demonstrated that selenium supplementation reduced liver cancer incidence in rats exposed to aflatoxin B1 (34) and also reduced the incidence of precancerous lesions of the liver in ducks (35). Subsequent trials in Jiangsu Province (35–37) examined the effects of selenium supplementation in various towns, in HBV-positive patients, and in families with high numbers of liver cancer cases, and each of the three studies showed that selenium considerably and statistically significantly reduced liver cancer risk. As discussed above, alpha-tocopherol (vitamin E) and beta-carotene were included in the antioxidant combination tested in the MRC/BHF Heart Protection Study (33), but numbers of cases were too low for examining the effects of these vitamins on liver cancer risk (29). Regarding the finding in our study by subgroups of alcohol consumption, people in Linxian consume small amounts of alcohol, and alcohol consumption in this area is not itself a risk factor for liver cancer mortality (data not shown). Therefore, we cannot interpret the etiologic significance of this finding.
In a second analysis, we compared liver cancer mortality in the seven individual treatment arms with that in the placebo-only arm. This analysis was done to examine whether a specific combination of factors has a stronger effect than the cumulative effect of these factors in reducing liver cancer mortality. There was no evidence that a combination of any two factors substantially or statistically significantly reduced liver cancer mortality. However, the treatment arm with all four factors had a lower risk of liver cancer death than the placebo group. This finding may suggest that a combination of several vitamins may reduce liver cancer mortality. An alternative explanation is that this apparent risk reduction is a chance finding due to multiple testing.
We used several statistical tests to examine the interactions between factors A–D and age, sex, smoking, alcohol consumption, and HBsAg status. Because of the number of tests, the nearly statistically significant interaction of age with factor A, the statistically significant interaction of age with factor B, the borderline statistically significant interaction of sex with factor C, the statistically significant interaction of alcohol consumption with factor D, and the lower risk of liver cancer mortality found in the interaction arm with all four factors need to be interpreted with caution.
The results of this study should also be interpreted in the context of the effects of vitamin supplementation on other cancers, as shown in this and other randomized trials. In the Linxian General Population Trial, factor D was associated with statistically significantly lower all-cause mortality, total cancer mortality, and gastric cancer mortality (13). In vitamin-replete populations, however, supplementation with retinol, vitamin E, or beta-carotene has not been associated with reduced risk of other major cancers, such as lung cancer (28,38), or with reduced risk of total mortality (39).
The strengths of this study are its randomized, double-blind design; its excellent compliance; its long-term follow-up, with complete ascertainment of cases; and its examination of previously untested factors for liver cancer prevention. This is the first major report, to our knowledge, of chemoprevention of liver cancer using several vitamins and minerals; only selenium has been tested in previous major trials. This study also has limitations. Interventions with factors containing multiple agents do not allow evaluation of the effects of individual agents alone. Also, the people of Linxian are deficient in many micronutrients (12,13) which may limit the generalizability of these results. Data on aflatoxin, an important risk factor for liver cancer, were not available. However, because this was a randomized study, aflatoxin exposure would not be expected to differ by supplement factor.
In summary, supplementation with combinations of vitamins and minerals at nutrient-repletion levels for 5.25 years did not reduce primary liver cancer mortality in this nutrient-inadequate population in Linxian, China. However, some combinations reduced risk in subgroups defined by age, sex, and alcohol consumption. These subgroup analyses need to be interpreted with caution.
|
Funding |
|---|
|
TopAbstractContext and CaveatsSubjects and MethodsResultsDiscussionFundingReferencesNotes |
|---|
National Cancer Institute (N01-SC-91030, N01-RC-47701); Intramural Research Program of the National Institutes of Health, National Cancer Institute.
|
NOTES |
|---|
|
TopAbstractContext and CaveatsSubjects and MethodsResultsDiscussionFundingReferencesNotes |
|---|
We acknowledge the following American and Chinese experts for their review of the diagnostic materials in this study: Klaus Lewin, Roberta Nieberg, Marvin Weiner, Guo-Qing Wang, Fu-Sheng Liu, Shu-Fan Liu, and Zheng-Yan Wang.
The sponsor did not have any role in the design of the study; the collection, analysis, and interpretation of the data; the writing of the manuscript; or the decision to submit the manuscript for publication.
|
REFERENCES |
|---|
|
TopAbstractContext and CaveatsSubjects and MethodsResultsDiscussionFundingReferencesNotes |
|---|
(1) Parkin DM, Bray F, Ferlay J, Pisani P. Global cancer statistics, 2002. CA Cancer J Clin (2005) 55:74–108.
(2) Kamangar F, Dores GM, Anderson WF. Patterns of cancer incidence, mortality, and prevalence across five continents: defining priorities to reduce cancer disparities in different geographic regions of the world. J Clin Oncol (2006) 24:2137–50.
(3) McGlynn KA, London WT. Epidemiology and natural history of hepatocellular carcinoma. Best Pract Res Clin Gastroenterol (2005) 19:3–23.[CrossRef][Medline]
(4) Hoofnagle JH. Hepatocellular carcinoma: summary and recommendations. Gastroenterology (2004) 127:S319–23.[CrossRef][Web of Science][Medline]
(5) Seeff LB. Introduction: the burden of hepatocellular carcinoma. Gastroenterology (2004) 127:S1–4.[CrossRef][Web of Science][Medline]
(6) Yu MC, Yuan JM. Environmental factors and risk for hepatocellular carcinoma. Gastroenterology (2004) 127:S72–8.[CrossRef][Web of Science][Medline]
(7) Kensler TW, Qian GS, Chen JG, Groopman JD. Translational strategies for cancer prevention in liver. Nat Rev Cancer (2003) 3:321–9.[CrossRef][Web of Science][Medline]
(8) Centers for Disease Control. Global progress toward universal childhood hepatitis B vaccine. Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5236a5.htm. [Last accessed: July 12, 2007.].
(9) Chang MH, Chen CJ, Lai MS, Hsu HM, Wu TC, Kong MS, et al. Universal hepatitis B vaccination in Taiwan and the incidence of hepatocellular carcinoma in children. Taiwan Childhood Hepatoma Study Group. N Engl J Med (1997) 336:1855–9.
(10) Kensler TW, Egner PA, Wang JB, Zhu YR, Zhang BC, Lu PX, et al. Chemoprevention of hepatocellular carcinoma in aflatoxin endemic areas. Gastroenterology (2004) 127:S310–18.[CrossRef][Web of Science][Medline]
(11) Yuan JM, Gao YT, Ong CN, Ross RK, Yu MC. Prediagnostic level of serum retinol in relation to reduced risk of hepatocellular carcinoma. J Natl Cancer Inst (2006) 98:482–90.
(12) Zou XN, Taylor PR, Mark SD, Chao A, Wang W, Dawsey SM, et al. Seasonal variation of food consumption and selected nutrient intake in Linxian, a high risk area for esophageal cancer in China. Int J Vitam Nutr Res (2002) 72:375–82.[CrossRef][Web of Science][Medline]
(13) Yang CS, Sun Y, Yang QU, Miller KW, Li GY, Zheng SF, et al. Vitamin A and other deficiencies in Linxian, a high esophageal cancer incidence area in northern China. J Natl Cancer Inst (1984) 73:1449–53.[Web of Science][Medline]
(14) Blot WJ, Li JY, Taylor PR, Guo W, Dawsey S, Wang GQ, et al. Nutrition intervention trials in Linxian, China: supplementation with specific vitamin/mineral combinations, cancer incidence, and disease-specific mortality in the general population. J Natl Cancer Inst (1993) 85:1483–92.
(15) Blot WJ, Li JY, Taylor PR, Li B. Lung cancer and vitamin supplementation. N Engl J Med (1994) 331:614.
(16) Tran GD, Sun XD, Abnet CC, Fan JH, Dawsey SM, Dong ZW, et al. Prospective study of risk factors for esophageal and gastric cancers in the Linxian general population trial cohort in China. Int J Cancer (2005) 113:456–63.[CrossRef][Web of Science][Medline]
(17) Li B, Taylor PR, Li JY, Dawsey SM, Wang W, Tangrea JA, et al. Linxian nutrition intervention trials. Design, methods, participant characteristics, and compliance. Ann Epidemiol (1993) 3:577–85.[Medline]
(18) Ershow AG, Zheng SF, Li GY, Li JY, Yang CS, Blot WJ. Compliance and nutritional status during feasibility study for an intervention trial in China. J Natl Cancer Inst (1984) 73:1477–81.[Web of Science][Medline]
(19) Li JY, Li GY, Zheng SF, Liu YY, Li P, Yang CS, et al. A pilot vitamin intervention trial in Linxian, People's Republic of China. Natl Cancer Inst Monogr (1985) 69:19–22.[Medline]
(20) McGlynn KA, Abnet CC, Zhang M, Sun XD, Fan JH, O’brien TR, et al. Serum concentrations of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) and risk of primary liver cancer. J Natl Cancer Inst (2006) 98:1005–10.
(21) Abnet CC, Qiao YL, Mark SD, Dong ZW, Taylor PR, Dawsey SM. Prospective study of tooth loss and incident esophageal and gastric cancers in China. Cancer Causes Control (2001) 12:847–54.[CrossRef][Web of Science][Medline]
(22) McAlister FA, Straus SE, Sackett DL, Altman DG. Analysis and reporting of factorial trials: a systematic review. JAMA (2003) 289:2545–53.
(23) Gray RJ. A class of K-sample tests for comparing cumulative incidence of competing risk. Ann Stat (1988) 16:1141–54.
(24) Blot WJ, Li JY, Taylor PR, Guo W, Dawsey SM, Li B. The Linxian trials: mortality rates by vitamin-mineral intervention group. Am J Clin Nutr (1995) 62:1424S–6.[Medline]
(25) Kamangar F, Qiao YL, Yu B, Sun XD, Abnet CC, Fan JH, et al. Lung cancer chemoprevention: a randomized, double-blind trial in Linxian, China. Cancer Epidemiol Biomarkers Prev (2006) 15:1562–4.
(26) Yu SZ. Primary prevention of hepatocellular carcinoma. J Gastroenterol Hepatol (1995) 10:674–82.[Web of Science][Medline]
(27) Yu MW, Hsieh HH, Pan WH, Yang CS, Chen CJ. Vegetable consumption, serum retinol level, and risk of hepatocellular carcinoma. Cancer Res (1995) 55:1301–5.
(28) Omenn GS, Goodman GE, Thornquist MD, Balmes J, Cullen MR, Glass A, et al. Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease. N Engl J Med (1996) 334:1150–5.
(29) Bjelakovic G, Nikolova D, Simonetti RG, Gluud C. Antioxidant supplements for prevention of gastrointestinal cancers: a systematic review and meta-analysis. Lancet (2004) 364:1219–28.[CrossRef][Web of Science][Medline]
(30) Muto Y, Moriwaki H, Ninomiya M, Adachi S, Saito A, Takasaki KT, et al. Prevention of second primary tumors by an acyclic retinoid, polyprenoic acid, in patients with hepatocellular carcinoma. Hepatoma Prevention Study Group. N Engl J Med (1996) 334:1561–7.
(31) Lemonnier FJ, Scotto JM, Thuong-Trieu C. Influence of riboflavin on disturbances in trytophan metabolism and hepatoma production after a single dose of aflatoxin B1. J Natl Cancer Inst (1975) 55:1085–7.[Web of Science][Medline]
(32) Hirakawa N, Okauchi R, Miura Y, Yagasaki K. Anti-invasive activity of niacin and trigonelline against cancer cells. Biosci Biotechnol Biochem (2005) 69:653–8.[CrossRef][Medline]
(33) Heart Protection Study Collaborative Group. MRC/BHF Heart Protection Study of antioxidant vitamin supplementation in 20536 high-risk individuals: a randomised placebo-controlled trial. Lancet (2002) 360:23–33.[CrossRef][Web of Science][Medline]
(34) Yu SY, Chu YJ, Li WG. Selenium chemoprevention of liver cancer in animals and possible human applications. Biol Trace Elem Res (1988) 15:231–41.[Web of Science][Medline]
(35) Yu SY, Zhu YJ, Li WG. Protective role of selenium against hepatitis B virus and primary liver cancer in Qidong. Biol Trace Elem Res (1997) 56:117–24.[Web of Science][Medline]
(36) Yu SY, Zhu YJ, Li WG, Huang QS, Huang CZ, Zhang QN, et al. A preliminary report on the intervention trials of primary liver cancer in high-risk populations with nutritional supplementation of selenium in China. Biol Trace Elem Res (1991) 29:289–94.[Web of Science][Medline]
(37) Li W, Zhu Y, Yan X, Zhang Q, Li X, Ni Z, et al. [The prevention of primary liver cancer by selenium in high risk populations]. Zhonghua Yu Fang Yi Xue Za Zhi (2000) 34:336–8.[Medline]
(38) The ATBC Cancer Prevention Study Group. The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers. The Alpha-Tocopherol, Beta Carotene Cancer Prevention Study Group. N Engl J Med (1994) 330:1029–35.
(39) Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C. Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis. JAMA (2007) 297:842–57.
Manuscript received November 27, 2006; revised June 6, 2007; accepted June 27, 2007.
Related Article in JNCI
CiteULike 
Connotea 
Del.icio.us What's this?
J Natl Cancer Inst 2007 99: 1213.
This article has been cited by other articles:
|
|
 |
|
  Y.-L. Qiao, S. M. Dawsey, F. Kamangar, J.-H. Fan, C. C. Abnet, X.-D. Sun, L. L. Johnson, M. H. Gail, Z.-W. Dong, B. Yu, et al. Total and Cancer Mortality After Supplementation With Vitamins and Minerals: Follow-up of the Linxian General Population Nutrition Intervention Trial J Natl Cancer Inst, April 1, 2009; 101(7): 507 - 518. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||