History of cancer research has always been closely linked with the history of biology. The rise of the cell theory in the middle of the nineteenth century led to a unified conception of cancer, and to a dramatic change in the description of this disease, as well as in its diagnosis and prognosis. Cancer research has been revitalised during the last three decades through the development and transformations of molecular biology. Cancer results from the accumulation of mutations in oncogenes (genes stimulating cell proliferation) and tumour-suppressor genes (genes limiting cell growth). At least six mutations are necessary for the formation of a tumour. Drugs specifically targeted against these molecular actors of cancer are progressively finding their place in chemotherapy. Simultaneously, new systemic and evolutionary visions of cancer are slowly emerging.

Key Concepts:

• Cancer has always been at the forefront of biological research.
  
• Molecular biology has profoundly transformed the vision of cancer.
  
• A succession of somatic mutations is required for the formation of a tumour.
  
• Drugs specifically targeted against the products of oncogenes are progressively entering into clinics.
  
• The growth and expansion of a tumour is seen now as an evolutionary process.
  
• In systems biology, cancer is seen as a new functional state of the cell.
  
• Epigenetic modifications might play a role in the formation of tumours.
  
• The role of cancer stem cells in the development of tumours is still discussed.