Download BIOL 207 Biology of Cancer

BIOL 207 Biology of Cancer
August 29, 2007
Lecture 1: What is cancer?
Reading: Chap. 1 Kleinsmith pp. 1-12
Outline:
1. Defining cancer
2. Many diseases
3. Normal vs. abnormal cells
4. Benign vs. malignant tumors
5. How cancers vary
6. Cancer diagnosis/staging

In your lifetimes, between 1 in 2 and 1 in 3 persons will be diagnosed with cancer.

Cancer—“crab”—family of diseases in which tissues grow and spread throughout
the body.

Disease has been around for thousands of years, but prevalence steadily
increasing as humans live longer.
Fig. 1-1 Relative frequencies of cancer cases. What does pie chart say?
 Most common cancer: skin cancer
 Also common: prostate, breast, lung, colorectal cancers
Relative frequency of cancer deaths:
 Deadliest cancer is lung cancer, followed by colorectal cancer and breast cancer.
 Skin cancer makes up a small fraction of cancer deaths.
 Pancreatic cancer makes up a small fraction of cancer cases, but is one of the
deadliest cancers.
Different regions of the world have different cancer incidences.
To make comparisons between death rates, these are adjusted per 100,000/year
Different cancers have different death rates; death rate trends may change over time.
Fig. 1-2 Describe the trends.
 Death rate due to lung cancer increased between 1930 and 1990, now declining
slightly.
Scientists look for factors affecting trends
 Lung cancer increases with increased smoking and passage of time.
Describe the trend in breast cancer death rates.
Describe the trend in stomach cancer death rates.
1
Biology of Cancer text
The author, Dr. Lewis Kleinsmith, is a professor in cell and molecular biology at the
University of Michigan. His focus is on the underlying science behind cancer and what is
going on in the cells.
Cancer cells have two properties
 Cell proliferate out of control
 Cancer cells spread throughout the body (metastasis)
Cells are the basic units of life.
Levels of organization:
Cells  tissues  organs  organ systems  individual
Initial stages of cancer deal with cells and tissues
Later stages deal with spread of cells via organ systems (circulatory, lymphatic)
Normal growth vs. abnormal growth of tissues
Hypertrophy—increase in cell size i.e. weight trainingmuscles
Hyperplasia—increase in cell number i.e. calluseswriting
Dysplasia—disorganized growth
Neoplasia—disorganized growth, increase in # of dividing cells
Fig. 1-4 Normal and neoplastic growth of skin
Normal skin: only basal cells divide; other cells migrate and differentiate
Skin tumor: cell division occurs among more cell types in several layers; lacks needed
specialized cells
Benign tumors—grow in a confined area
Malignant tumors—can invade surrounding tissues, enter bloodstream, spread to different
parts of the body by metastasis
A cancer is any malignant tumor.
Cancers vary in their site of origin.
Lung vs. liver cancer
Cancers vary in the cell type of origin
Carcinoma vs. sarcoma vs. leukemia
epithelia
muscle
blood
90%
1%
9% of all human cancers
2
Leukemia—cancer of circulating blood
Lymphoma—solid tumor containing many blood cells
Table 1-2 Naming tumors
Cancers vary in their survival rates.
Table 1-3; Fig. 1-6
~99% of patients survive 5 yrs with skin cancer
~20% of patients survive 5 yrs with lung cancer
Cancer diagnosis
Remove tissue—biopsy
Pathologist examines for tumor under microscope
Looks for evidence of malignancy
Table 1-4 Microscopic difference benign vs. malignant tumors
Pathologist “grades” the tumor based on differences in size, microscopic appearance and
evidence of metastasis
Grade 1: benign tumors    grade 4 metastatic tumors
Tumors can also be categorized based on their clinical stage.
In staging, the estimated progression of a person’s cancer is correlated with prospects for
successful treatment.
TNM system
T = tumor size
N =lymph node
M = metastasis
(1) How large is the tumor and how far has it invaded into surrounding tissues?
(2) Are lymph nodes positive for cancer cells (have cancer cells spread to regional lymph
nodes?
(3) To what extent have cancer cells metastasized to other organs?
Lower combined TNM# --cancer detected early and hasn’t spread
Higher combined TNM#--more difficult to treat successfully
Example: Staging of colon and rectum cancer
Classification
Tis
T1
T2
T3
Description
Carcinoma in situ
Invasion into submucosa layer of colon wall
Invasion into submucosa into underlying muscular layer
Invasion through muscular layer
3
T4
N0
N1
N2
N3
M0
M1
Invasion into peritoneal cavity and adjacent organs
Regional lymph nodes free of tumor
1-3 positive nodes
4 or more positive nodes
Positive nodes on named vascular trunk
No distant metastases
Distant metastases present
Proper staging is critical to proper diagnosis and treatment
TNM stage
T1N0M0
T4N0M0
T4N1M0
Five year survival rate
>90%
60-70%
40%
4
Treatment
surgery
surgery
surgery and chemo or radiation