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Cancer

Cancer. Chapter 4 Supplement. Cancer - important facts. Cancer is uncontrolled cell growth It requires several steps to form It is very different depending on which tissues are affected It is a leading cause of death in the U.S. and other developed nations (Behind cardiovascular disease).

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Cancer

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  1. Cancer Chapter 4 Supplement

  2. Cancer - important facts • Cancer is uncontrolled cell growth • It requires several steps to form • It is very different depending on which tissues are affected • It is a leading cause of death in the U.S. and other developed nations (Behind cardiovascular disease)

  3. Cancer and Cell Division • Cancer disrupts cellular controls on cell division • Remember Interphase (G1, S, G2) and Mitotic phase? Figure 3.30

  4. Cancer and Cell Division • Normally, checkpoints keep cells from passing from one stage of the cell cycle to the next (e.g. S phase  G2) • Cancer causes cells to lose the ability to stop cell division at these checkpoints and so the cells divide continuously and beyond control

  5. How Mutations lead to cancer • Mutations disrupt normal controls over cell growth and division • Uncontrolled growth increases error rates • Thus cancers often begin where “stem cells” are dividing rapidly and are very rare in cells that do not divide. • Where would you expect more cancers to occur: in the heart or in the colon?

  6. Cancer Stages • Cancer develops in steps: • Abnormal cell – genetic mutations cause uncontrolled growth • Primary tumor – mass of cells develops, often in one area • Metastasis – cells from tumor enter blood stream • Secondary tumor(s) – these cells take up residence in other parts of the body, forming new tumors there

  7. Development of Cancer - Metastasis • Invasion – abnormal cells grow into surrounding tissues • Penetration – cells enter the bloodstream • Escape – cells leave bloodstream to for secondary tumor

  8. Cell Division and Tumors • Tumors (neoplasms): • enlarged mass of cells • abnormal cell growth and division 1. Malignant tumor: • Spreads into surrounding tissues (invasion) • Can start new tumors (metastasis) 2. Benign tumor: • Contained (no invasion) • not life threatening (but may become malignant)

  9. Cancer and Genes • Genes that when mutated tend to cause cancer come in two types • Oncogenes • Dominant (only one mutation needed to lose control of growth) • Tumor suppressor genes: • Recessive (need two mutated copies) • Examples: BRCA1, Rb1

  10. Cancer and Genes • The key to cancer: Whether the first mutation is inherited, like BRCA1, or spontaneous, cells need to accumulate more than one key mutation to become malignant. • However, each mutation makes the accumulation of further mutations more likely.

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