The Emperor of All Maladies: A Biography of Cancer

by Siddhartha Mukherjee

How many “rules,” then, could Weinberg and Hanahan evoke to explain the core behavior of more than a hundred distinct types and subtypes of tumors? The question was audacious in its expansiveness; the answer even more audacious in its economy: six. “We suggest that the vast catalog of cancer cell genotypes is a manifestation of six essential alterations in cell physiology that collectively dictate malignant growth.” 1. Self-sufficiency in growth signals: cancer cells acquire an autonomous drive to proliferate—pathological mitosis—by virtue of the activation of oncogenes such as ras or myc. 2. Insensitivity to growth-inhibitory (antigrowth) signals: cancer cells inactivate tumor suppressor genes, such as retinoblastoma (Rb), that normally inhibit growth 3. Evasion of programmed cell death (apoptosis): cancer cells suppress and inactivate genes and pathways that normally enable cells to die. 4. Limitless replicative potential: cancer cells activate specific gene pathways that render them immortal even after generations of growth. 5. Sustained angiogenesis: cancer cells acquire the capacity to draw out their own supply of blood and blood vessels—tumor angiogenesis. 6. Tissue invasion and metastasis: cancer cells acquire the capacity to migrate to other organs, invade other tissues, and colonize these organs, resulting in their spread throughout the body.