Breast cancer screening aims to help women by early identification and treatment of cancers that might otherwise be life-threatening. However, breast cancer screening also leads to the detection of some cancers that, if left undetected and untreated, would not have damaged the health of the women concerned. At the time of diagnosis, harmless cancers cannot be identified as non-threatening, therefore women are offered invasive breast cancer treatment. This phenomenon of identifying non-harmful cancers is called overdiagnosis. Overdiagnosis is morally problematic as (...) it leads to overall patient harm rather than benefit. Further, breast cancer screening is offered in a context that exaggerates cancer risk and screening benefit, minimises risk of harm and impedes informed choice. These factors combine to create pathogenic vulnerability. That is, breast cancer screening exacerbates rather than reduces women’s vulnerability and undermines women’s agency. This paper provides an original way of conceptualising agency-supporting responses to the harms of breast cancer overdiagnosis through application of the concept of pathogenic vulnerability. (shrink)