Long-term cancer survivorship is an emerging field that focuses on physical late-effects and psychosocial implications for the inflicted. This study wishes to cast light on the underlying ontological aspect of long-term survivorship by philosophically exploring how being in life post cancer is perceived by survivors. Sixteen in-depth interviews with 14 Danish cancer survivors were conducted by the author. Having faced a life-threatening disease but no longer being in imminent danger of dying, survivors still considered death a defining yet dynamic component in their approach to life as a moving toward the end, sparking a sense of vitality in mortality. In order to unfold the interviewees’ renewed existential understanding post cancer, this study employs Martin Heidegger’s ontological analysis of death. In survivorship, my participants can thus be understood as being left with the perpetual choice between living in inauthenticity or in authenticity. The difference between the two modes of existence exhibits two diverging ways of relating to death, self, and being-in-the-world. At the same time, the role of death in long-term survivorship reflects back on the magnitude of the initial existential and moral upheaval triggered by the cancer diagnosis. Understanding the role of death in long-term survivorship can positively inform the field of cancer rehabilitation and long-term survivor care.