[Breast cancer: dangers of alleged certainties].

The artificial increase of breast cancer incidence is estimated as amounting to 30,000 new cases in the year 2000 in France. This increase would be attributable to a 1.2% lack of specificity for the whole range of diagnostic procedures. Sociologically, it appears that the Hippocratic devise "primum nil nocere" ("first don't harm") has been replaced today by "primum agere" ("act first"). Professionals should give information about both limitations and risks of screening. From an ethical point of view, screening programs justify themselves arguing that "there can't be harm in doing good". Absence of alternative strategies is not a sufficient argument for justifying screening with its uncertain consequences.