Informing but convincing : medical uncertainty and statistical rhetoric in oncology This article deals with the professional management of medical uncertainty in oncology. It is based on the observation and analysis of the ways in which doctors pass the diagnosis of a breast cancer on to their patients in France. It examines how doctors try to help their patients cope with the uncertainty of such a diagnosis. The announcement of a breast cancer goes hand in hand with prognostic considerations that forge the state of expectancy with which patients will have to cope for many years, and such a practice demonstrates a change in medical behaviour with regard to probability logic: by sharing the uncertainty with their patients, French oncologists are admitting the boundaries of an aspect of medicine that cannot function solely on the basis of eradication. The article looks at the implications of this, within the framework of current experiments on "announcing diagnoses".