The rate of urinary cortisol excretion at work is persistently elevated in women at familial risk for breast cancer

We recently reported that healthy women at familial risk for breast cancer (FH+) have higher urinary cortisol levels at work than women without familial risk (FH-). The purpose of this study was to evaluate whether this group difference persisted over a 1-month period. Subjects were healthy women (FH+, N = 42, age = 37.6 ± 9.3, FH-, N = 93, age 38.4 ± 9.0) employed primarily in clerical or technical positions at three medical centers in New York City who collected timed urine samples in three contrasting daily environments, at work (∼11AM-3PM), home (∼6PM-10PM) and during sleep (∼10PM-6AM) on 2 mid-week workdays ∼1 month apart. Two-way repeated measures ANOVA revealed that cortisol excretion differed across the environments (P < 0.001), and that there was also a significant interaction between daily environment and family history group (P < 0.049), such that FH+ women maintained higher cortisol excretion at work over the 2 days than FH- women. A Bland-Altman plot showed that both overall and by family history group, the rate of cortisol excretion at work was generally reproducible, although there was a heteroscadasticity in the relationship that likely reflected excessive stressfulness on one of the study days in a small minority of subjects. These results suggest that the presence of a potent background stressor (familial breast cancer risk) can influence more acute cortisol responses in daily life over time.