Circadian rhythm chaos: A new breast cancer marker

The most disappointing aspect of breast cancer treatment as a public health issue has been the failure of screening to improve mortality figures. Sinc e treatment of late-stage cancer has indeed advanced, mortality can only be decreased by improving the rate of early diagnosis. From the mid-1950s to the mid-1970s, it was expected that thermography would hold the key to brea st cancer detection, as surface temperature increases overlying malignant t umors had been demonstrated by thermographic imaging. Unfortunately, detect ion of the 1-3 degreesC thermal differences failed to bear out its promise in early identification of cancer. In the intervening two-and-a-half decade s, three new factors have emerged: it is now apparent that breast cancer ha s a lengthy genesis; a long-established tumor-even one of a certain minimum size-induces increased arterial/capillary vascularity in its vicinity; and thermal variations that characterize tissue metabolism are circadian ("abo ut 24 hours") in periodicity. This paper reviews the evidence for a connect ion between disturbances of circadian rhythms and breast cancer. Furthermor e, a scheme is proposed in which circadian rhythm "chaos" is taken as a sig nal of high risk for breast cancer even in the absence of mammographic evid ence of neoplasm or a palpable tumor. Recent studies along this line sugges t that an abnormal thermal sign, in the light of our present knowledge of b reast cancer, is ten times as important an indication as is family history data.