Estrogen metabolites (EM), including estrone and estradiol, have no relationship to colorectal cancer (CRC) in postmenopausal women, according to a study published online in the journal Cancer Epidemiology, Biomarkers & Prevention.
Participants in the study included 15,595 women between 55 to 80 years who donated blood between 1992 and 1993 for cancer through December 2004. A panel of 15 EM (eg, estrone and estradiol) was measured from 187 cases of CRC.
Results showed no significant associations between estrone (HRQ4 v Q1 = 1.15; 95% CI: 0.69, 1.93; Ptrend =0.54), estradiol (HRQ4 v Q1= 0.98; 95% CI: 0.58, 1.64; Ptrend >0.99) or total EM (the sum of all EM; HRQ4 v Q1=1.35; 95% CI: 0.81, 2.24; Ptrend=0.33) and CRC risk.
Specifically, the metabolites with a 2-, 4-, or 16-pathway had no related risk. However, a borderline trend was observed with high levels of 17-epiestriol.
The study suggests that future research focus on understanding how exogenous estrogen may be associated with prevention of CRC.
A potential protective role for estrogen in colon carcinogenesis has been suggested based on exogenous hormone use, but it is unclear from previous studies whether endogenous estrogens are related to colorectal cancer (CRC) risk.