Pre-Diagnostic Enterolactone Levels And Mortality Among Danish Men Diagnosed With Prostate Cancer

Anne ERIKSEN, Danish Cancer Society Research Center, Denmark
KYRØ C. 1 , NØRSKOV N. 2 , CHRISTENSEN J. 1 , BOLVIG A. 2 , TJØNNELAND A. 1 , OVERVAD K. 3 , LANDBERG R. 4 , OLSEN A. 1

1 Unit of Diet, Genes and Environment, Danish Cancer Society Research Center, Strandboulevarden 49, 2100 Copenhagen, Denmark
2 Department of Animal Science, Aarhus University, Blichers Allé 20, 8830 Tjele, Denmark
3 Department of Public Health, Section for Epidemiology, Aarhus University, Bartholins Allé 2, 8000 Aarhus C, Denmark
4 Department of Food Science, Swedish University of Agricultural Sciences, Almas Allé 5, 750 07 Uppsala, Sweden

Purpose: Prostate cancer is the most common cancer and the second most common cause of cancer-related death among Northern European men. Currently, there is a lack of knowledge about what men with prostate cancer can do to improve their prognosis. Lignans are phytoestrogens found as phenolic compounds in seeds, whole grains, nuts, and in some fruits and vegetables. In Denmark, whole-grain rye is the main source of lignans. Facilitated by the microbiota, plant lignans are converted to enterolignans (mainly enterolactone), and thereafter absorbed through the colonic barrier. Intervention trials have indicated that diets rich in whole-grain rye, and thereby lignans, may have beneficial effects on disease progression in prostate cancer patients. Therefore, the objective of this study was to investigate, in a prospective setting, the association between pre-diagnostic enterolactone levels and mortality among men diagnosed with prostate cancer.
Methods: The association between pre-diagnostic plasma enterolactone levels and all-cause mortality as well as prostate cancer-specific mortality was investigated in 1431 incident prostate cancer cases from the Danish “Diet, Cancer and Health” cohort study. These were followed from diagnosis until death (n=460, due to prostate cancer n=301), or end of follow-up (December 31, 2013). Enterolactone levels were analysed using a LC-MS/MS method, and information on vital status and cause of death was obtained through registries. Cox proportional hazards models with follow-up time as underlying time, stratified by 5-year intervals and adjusted for lifestyle factors, were used to estimate hazard ratios.
Results: High levels of enterolactone were associated with lower all-cause mortality, but the association was no longer statistical significant after adjusting for potential confounders. No association was found with prostate cancer-specific mortality.
Conclusions: High enterolactone concentrations were not associated with improved survival in a population of Danish men diagnosed with prostate cancer.                                                                                      
Funding source: Innovation Fund Denmark and Danish Cancer Society