Fecal steroid metabolites and breast cancer risk.

Women with breast cancer (n = 78) had a higher excretion of total fecal steroids in mg/gm of dry weight (56 + 37) compared to controls (45 + 29; n = 71) (P = 0.03). Increases in both total neutral steroids and total bile acids in cases contributed to this significant difference. Lean women (Quetelet's index less than 3.5) with breast cancer seemed to have inappropriately high excretion of total fecal steroids (56 +/- 35), which was significantly higher than that of controls (41 +/- 27) (P = 0.03). Obesity resulted in higher excretion of fecal steroids only in controls. The differences persisted, even after pairing control cases for race-ethnicity and menopausal status. In 59 such pairs, cases had higher values (56 +/- 33), compared to controls (41 +/- 26) (P = 0.008). Significant differences (P = 0.005) were also present in 24 postmenopausal pairs, while in 35 premenopausal pairs a similar trend, but no significant differences were noted. Women with benign breast disease had higher total fecal steroids (51 +/- 34) compared to other controls (38 +/- 21) (P = 0.05). This observation suggests a common etiology between benign breast disease and breast cancer. There were no significant differences in dietary intake of total calories, total fat or dietary cholesterol between controls and cases suggesting that the observed differences in fecal steroids could be attributed to higher endogenous synthesis of cholesterol in cases.