Breast Cancer Screening Trials: Endpoints and Over-diagnosis
A partir de l'analyse des données de 9 essais randomisés lancés entre 1963 et 1990 et évaluant le dépistage du cancer du sein par mammographie du point de vue de la mortalité spécifique, cette étude met en évidence la nécessité d'utiliser de meilleurs critères de jugement dans les essais cliniques pour éviter le surdiagnostic et le surtraitement
Screening mammography was assessed in nine randomized trials initiated between the years 1963-1990, with breast cancer-specific mortality as the primary endpoint. In contrast, breast cancer detection has been the primary endpoint in most screening trials initiated during the past decade. These trials have evaluated digital breast tomosynthesis (DBT), magnetic resonance imaging (MRI), and ultrasound, and novel screening strategies have been recommended solely on the basis of improvements in breast cancer detection rates. Yet, the assumption that increases in tumor detection produce reductions in cancer mortality has not been validated, and tumor-detection endpoints may exacerbate the problem of over-diagnosis. Indeed, the detection of greater numbers of early-stage breast cancers in the absence of a subsequent decline in rates of metastatic cancers and cancer-related mortality is the hallmark of over-diagnosis. There is now evidence to suggest that both ductal carcinoma in situ (DCIS) and invasive cancers are over-diagnosed as a consequence of screening. For each patient who is over-diagnosed with breast cancer, the adverse consequences include unnecessary anxiety, financial hardships, and a small risk of morbidity and mortality from unnecessary treatments. Moreover, the over-treatment of breast cancer, as a consequence of over-diagnosis, is costly and contributes to waste in healthcare spending. In this article, we argue that there is a need to establish better endpoints in breast cancer screening trials, including quality of life and composite endpoints. Tumor-detection endpoints should be abandoned, as they may lead to the implementation of screening strategies that increase the risk of over-diagnosis.
Journal of the National Cancer Institute , résumé, 2019