Fitness landscapes have long served as a conceptual tool in evolutionary biology. In recent 2 years, however, they have shifted from being viewed primarily as theoretical constructs 3 to being used to interpret experimental data and, increasingly, to guide evolutionary 4 outcomes in biomedical systems. In this review, we trace that progression across major 5 landscape formalisms, including Fisher’s geometric model, Wright’s adaptive landscape, 6 fitness seascapes, and empirical fitness landscapes. We aim to highlight the strengths 7 of each model and its potential for use in cancer research. Rather than treating these 8 frameworks as isolated models, we show how they collectively reflect the field’s maturation: 9 from describing adaptation in idealized settings to quantifying epistasis and evolutionary 10 accessibility, to interpreting experimental genotype-fitness data, and finally to motivating 11 strategies for steering evolution in contexts such as treatment resistance in cancer. We argue 12 that the central promise of the fitness landscape framework now lies not only in explaining 13 evolutionary dynamics, but also in enabling predictive interventions and overcoming 14 cancer evolution.