Spiegel - Sephton JNCI 2002 COMMENT

tors for breast cancer that are associated sleep disruption with cancer risk may bewith sleep disruption. For example, our mediated by a number of pathways, in-laboratory has recently reported, also in cluding, but not limited to, the disrup-tion of melatonin secretion. There arethe Journal, that loss of normal diurnalnow sufficient data to support the notionvariation in cortisol predicts early mor-that the loss of normal diurnal variationtality in metastatic breast cancer (3).in cortisol is another possible mecha-Cortisol normally shows marked diurnalnism that could account for the observedvariation, peaking in early morning andassociation between shift work anddeclining throughout the day. In ourbreast cancer incidence.study, patients with flattened salivarycortisol rhythms or aberrant peaks and DAVID SPIEGELtroughs suffered earlier mortality. The SANDRA SEPHTONprognostic effect of cortisol rhythm onREFERENCESsurvival emerged approximately 1 yearafter cortisol assessment and extended at(1) Schernhammer ES, Laden F, Speizer FE, Wil-least 7 years after the assessment (3). A lett WC, Hunter DJ, Kawachi I, et al. Rotatingsimilar association between 24-hour night shifts and risk of breast cancer in womenparticipating in the nurses’ health study. J Natlrest–activity rhythms and survival hasCancer Inst 2001;93:1563–8.been noted in patients with colorectal(2) Davis S, Mirick DK, Stevens RG. Night shiftcancer (4). Furthermore, patients at highwork, light ...