Download What is Cancer?

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