This case-cohort study examined the association between plasma
enterolactone concentration and incidence of colon and
rectal cancer in the Diet,
Cancer and Health cohort, which enrolled 57,053 participants aged 50-64. Information about diet and lifestyle was obtained by questionnaire, and data on prescriptions of
antibiotics were obtained from the Danish Prescription Registry. Cases diagnosed during 5.9 years of follow-up and a randomly selected sample of the cohort had a plasma sample analyzed for
enterolactone by time-resolved fluoro-immuno assay. Associations were analyzed by Cox proportional hazards model. A total of 244
colon cancer cases, 137
rectal cancer cases, and 370 sub-cohort members were included in the statistical analyses. For each doubling in
enterolactone concentration, we found lower risk of
colon cancer among women [
IRR (95% CI) = 0.76 (0.60-0.96)] and a tendency toward lower risk of
rectal cancer [
IRR (95% CI) = 0.83 (0.60-1.14)]. Among men, a doubling in
enterolactone tended to be associated with higher risk of
colon cancer [
IRR (95% CI) = 1.09 (0.89-1.34)] and was associated with statistically significantly higher risk of
rectal cancer [
IRR (95% CI) = 1.74 (1.25-2.44)]. Exclusion of
antibiotics users strengthened the results slightly. In conclusion, with higher
enterolactone levels, we found lower risk of
colon cancer among women and higher risk of
rectal cancer among men.