Autophagy is an attractive therapeutic target in cancer. Successful autophagy-focused clinical intervention will require a detailed understanding of when and where autophagy is important during tumorigenesis. In this issue of Cancer Research, Khayati and colleagues use state-of-the-art genetically engineered mouse models to demonstrate that transient systemic inhibition of autophagy can irreversibly impair the growth of established lung tumors with a good tolerability in normal tissues, suggesting a therapeutic strategy for cancer treatment. See related article by Khayati et al., p. 4429.