Future challenges in secondary prevention of breast cancer for women at high risk.

We are making great progress in singling out those among us who are at high risk of cancer, whether on the basis of epidemiologic characteristics that predict risk in the absence of a firm knowledge of mechanism or, more recently, by specifying the genetic site of a factor that unequivocally puts a specific person in danger. We have been less capable of identifying factors that, given awareness of increased risk, determine whether or not a person adopts an appropriately self-protective behavior. This article reports the experience of female twins whose co-twins have a diagnosis of breast cancer. Such individuals can be assumed to have been presented with incontrovertible evidence of their elevated risk almost as much as if they had been found to have a dangerous gene. Their subsequent actions can shed light on why persons do not always take steps to protect themselves from a clear but future danger. It is evident that cognition is not the sole, or even the most important, determinant of health promoting behavior. Among the others are beliefs about cancer causality and the state of personal health, the details of the medical experience of relatives, and the degree to which perceptions of that experience have intruded into consciousness. The gap between rational and actual efforts to reduce personal risk is great, and if technology is to offer us the benefits promised, we must give priority to narrowing that gap.