Normal cell proliferation, which is essential for tissue and organ repair, is tightly regulated. Cancer is a deregulated metabolic disease. This deregulation allows cancer cells to become independent of the control mechanisms that regulate cell division and the cell cycle. Cells with few oncologic properties are gradually selected for this independence, which can become aggressive as more growth-promoting factors are added, leading to malignant transformation after a long benign phase. Mutations or epigenetic deregulation cause reduced control over cell proliferation, often ignoring mitogenic signals, and result in metabolic reprogramming that boosts nutrient uptake, anabolic reductive reactions, and redox balance. As a result, cancer therapy mainly targets blocking growth-promoting pathways used in normal cell growth, but this often causes systemic toxicity due to disruption of organismal homeostasis. Despite major advances in understanding cancer biology and how anticancer drugs function, targeting growth pathways such as nucleotide, protein, and lipid synthesis while minimizing side effects remains challenging. This review provides an update on cancer biology and the targetable pathways in cancer therapy, with selected examples of inhibitor molecules.