How did the discovery of oncogenes reshape scientists’ understanding of cancer?

The discovery of oncogenes fundamentally reshaped the scientific understanding of cancer by shifting the focus from external infectious agents to the internal molecular mechanisms of the cell.12

Initially, researchers hypothesized that cancer was caused by viral agents. However, the identification of the src gene and subsequent work by J. Michael Bishop and Harold Varmus revealed that oncogenes are actually derived from normal cellular genes, termed proto-oncogenes. This discovery established that cancer is a disease of the genome, arising when these normal regulators of cell growth and differentiation are mutated, amplified, or translocated, leading to uncontrolled proliferation.12

In the context of translational medicine, this paradigm shift provided concrete molecular targets for therapy. By identifying specific genetic anomalies—such as the BCR-ABL fusion protein—scientists moved beyond broad-spectrum treatments to develop targeted therapies that selectively inhibit the drivers of tumor growth while sparing healthy cells. This transition from viewing cancer as a mysterious, systemic illness to a manageable disease driven by specific molecular pathways is a cornerstone of modern precision medicine.32