Most biological processes such as tumorigenesis or aging have been considered to be irreversible, but historically there have been some interesting observations implying the possibility of their reversion. This actually suggests a potential paradigm change. For instance, current cancer treatments predominantly rely on killing cancer cells. However, from an evolutionary perspective, this approach inherently leads to challenges such as drug resistance, recurrence, and adverse side effects. What if cancer cells could be reprogrammed to revert to a state resembling normal cells instead of being destroyed? In this talk, I will introduce a concept of ‘cancer reversion’, a novel therapeutic strategy that aims to restore cancer cells to a non-malignant state. Moreover, our recent research findings will be discussed, highlighting how this approach has the potential to overcome the fundamental limitations of conventional anticancer therapies. I will further extend this approach to reverse-aging with one successful story.