THE PATTERN OF HORMONAL CIRCADIAN TIME STRUCTURE (ACROPHASE) AS AN ASSESSOR OF BREAST-CANCER RISK

Though many hormones are secreted in a pulsatile manner, their secreti on pattern can be superimposed by a 24-hour sinusoidal curve. The sinu soidal curve is then characterized by the estimated peak clock time lo cation (acrophase), the adjusted mean (mesor) and the amplitude. When the distribution of the acrophases of 12 hormones was compared among w omen with regard to their age and to the level of risk of developing b reast cancer, statistically significant differences were revealed betw een distribution patterns of acrophases of women with high (n = 12 and 45 circadian profiles) or low (n = 12 and 41 circadian profiles) risk of developing breast cancer. However, when the amplitude/mesor ratios of the corresponding hormonal rhythms were analyzed, significant diff erences occurred between age groups rather than between risk levels. T hese observations suggest that the endocrine time structure between in dividual women can be used as an assessor of breast-cancer risk. (C) 1 996 Wiley-Liss, Inc.