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Biology 207 Biology of Cancer Spring 2004 Lecture 1: What is Cancer? Reading: King Chapter 1 Outline: 1. Cancer defined 2. Multiple changes lead to cancer 3. Genes and environment 4. Common cancers 5. How does a normal cell become a cancer cell? 6. Cancer prognoses Lecture: 1. What is cancer? How would you define cancer? A collection of different diseases Cancers display uncontrolled growth Metastasis=Migration from the site of origin Cancer=malignant growth Malignant=ability of growth to migrate and invade surrounding tissues Neoplasm=new growth Tumor=benign (harmless) and malignant growths 2. Multiple changes lead to cancer Requires multiple exposures to chemicals or radiation, leading to changes in DNA Cell can repair some damage Cell can commit suicide (programmed cell death) if badly damaged Cancers except leukemia associated with age (Fig. 1.1) 3. What influences cancer? Environment/lifestyle U.S. smoking lung cancer China smoked or pickled foods stomach cancer Fig. 1.2 Five most common cancers U.S. vs. China Heredity Certain cancers run in families Breast cancer Retinoblastoma (cancer affecting the eye) 1 4. Most common cancers Carcinomas=cancers of the epithelial cells (cells that cover the body or line body cavities) Epithelia are actively dividing Exposed to chemicals or radiation Table 1.1 Men vs. women differences in cancer incidence Death rates for the same kind of cancer can vary between men and women 5. How does a normal cell become a cancer cell? Organisms are made of cells Cells work together in tissues Diagram of normal skin How can a single cell from skin go on to form skin cancer? Cancer cells divide when they shouldn’t don’t cooperate don’t respond to normal signals don’t do their specialized job migrate away from their original site enter the blood stream move to other parts of the body Growth of a tumor depends on Nutrients Blood supply Survival of cancer cells depends on Escaping detection Finding fertile ground to migrate to 6. Cancer prognoses Cancer wouldn’t be so bad if it didn’t kill people Prognoses vary for different cancer types Heart disease leading cause of death Cancer second leading cause of death Pancreatic cancer: Poor prognosis; death in 5 years for 97% Testicular cancer: Excellent prognosis; 91% survive 5 years or more 2 Prognosis depends on: Type of cancer Time of diagnosis Reliability of cancer testing Treatment strategy Access to treatment 3