Introduction The aetiology of pancreatic cancer is largely unknown although the antioxidants vitamin E, vitamin C and selenium may prevent carcinogenesis by preventing free radical induced cell damage. The aim of this study was to investigate whether these micronutrients affect the risk of developing pancreatic cancer, for the first time in a prospective cohort study, using seven-day food diaries (7-DFDs) to estimate anti-oxidant intake.
Methods A total of 25 639 men and women aged 45–74 years were recruited between 1993 and 1997 into the European Prospective Investigation into Cancer-Norfolk and completed 7-DFDs. The dietary intakes of vitamin C, vitamin E and selenium were calculated using a computer program containing information on 11 000 food items. The cohort was monitored for 16 years to identify those who developed pancreatic cancer. Each case was matched with four controls for age and sex and conditional logistic regression used to calculate OR and 95% CI for the intake of each antioxidant, adjusted for smoking, diabetes and total energy intake. To look for a threshold effect the OR was calculated comparing the lowest quintile of each antioxidant with a combination of the higher four quintiles.
Results During follow-up, 81 participants (51% men) developed pancreatic cancer (mean age=71.4 years, SD=8.6 years). The four highest quintiles of vitamin E were negatively associated with the development of pancreatic cancer, although there was no dose-dependent effect (OR for the fourth highest quintile vs the lowest=0.37, 95% CI 0.16 to 0.88 p=0.03, OR for the fifth quintile=0.46, 95% CI 0.19 to 1.11, p=0.09). The OR for the lowest quintile compared to a summation of the four highest quintiles was 0.45 (95% CI 0.24 to 0.85, p=0.01). No significant associations were found for the dietary intakes of either vitamin C or selenium.
Conclusion This is the first prospective epidemiological study, using detailed 7-DFDs, to demonstrate a protective effect of vitamin E in the development of pancreatic cancer. These results suggest vitamin E should be measured in future work on the aetiology of this cancer. Consistent findings together with plausible biological mechanisms would support measures to increase the dietary intake of vitamin E in the population.