This paper argues that breast cancer prognosis potentially produces a circular dialectic in which a) the subject is compelled to perceive the body as vulnerable and separate (alien) to the self, and the treatments required make the body more vulnerable, more alien and b) this is held in tension with the fact that the very alienation and heightened vulnerability of the body in breast cancer treatment is productive; it collapses the boundaries through which the body and self are understood, often demands a conscious intimacy of/with the body, and points to critical enactments and understandings of embodied subjectivity. I use the concept of dialectics here in a broad sense then, to mark the interaction of apparently conflicting states. While vulnerability is generally thought of as a somato-ontology to be avoided, and as a constraining, negative mode of being, through a shift in perspective it also appears as an enabling state. I argue that vulnerability might be seen as a relational ontology between flesh and self that is both restrictive and generative, where the restriction itself can be generative. Understanding vulnerability in this way might engender the critical politicization of risk and function as the place from which a radically altered/re-conceived politics proceeds. Such a politics would be ethico-political work around the issue of cancer. It would, perhaps, function ultimately as an ethics of vulnerability, foregrounding critical responsibility towards oneself, one’s life, the life of others, and the life of the community.