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Chapter 12 The Biology and Treatment of Cancer
CHAPTER OUTLINE
12.1 Cancer is a major killer.
Society's concern over deaths caused by cancer has resulted in tremendous amounts of
resources granted to cancer research.
12.2 Cancer is a diverse set of diseases that share certain common features.
Cancer is the result of uncontrolled cell proliferation resulting in a malignant tumor from
which cells are able to spread to other tissues, a process called metastasis. Benign tumors
are masses of cells which are contained.
12.3 Cancer is a genetic disease.
Scientists have discovered that cancer is based on mutations within DNA. Faulty
proteins result in loss of cell adhesion, failure to enter apoptosis and stimulation of
angiogenesis in tumors.
12.4 Abnormal proteins are responsible for the abnormal traits of cancer cells.
Mutated genes result in abnormal proteins.
Cell proliferation is the central abnormality in cancer cells.
The cell cycle is under rigid control, control which can be lost with genetic mutations.
Tumor suppressor proteins and proto-oncogene proteins are involved in regulating the
cell cycle. An oncogene, which is a mutated proto-oncogene, is often found in cancer
cells and contributes to the disease. Another mutation may result in overexpression of
receptor proteins for growth factor. Yet another important protein, p53, guides a cell to
apoptosis when mutated DNA is found; loss of p53 function can be a participant in
cancer.
Cancer cells often lack mature structure and function.
Cancer cells do not specialize or function as they are meant to in the tissue where they are
found.
Cancer cells can stimulate the growth of blood vessels.
Cancer cells stimulate angiogenesis in order to provide a blood supply to the tumor.
Cancer cells escape from adjacent cells.
Cancer cells lose their ability to adhere to neighboring cells as would be normal within a
tissue.
Often cancer cells are not killed by the mechanisms that kill other abnormal cells.
Both the immune system and the p53 protein function in removing abnormal cells from
the body. Cancer cells can escape these mechanisms.
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12.5 Risk factors increase or decrease your chances of developing cancer.
Because of the complexity of cancer, certain risk factors increase or decrease the chance
of developing cancer but do not determine that cancer will or will not occur.
Inherited cancer genes account for only a small percentage of cases of cancer.
Mutated genes which contribute to cancer can be inherited but typically are not the sole
cause of cancer.
Some environmental agents can cause cancer.
Carcinogens can cause genetic mutations contributing to cancer
Any factor that increases cell proliferation increases the risk of cancer.
Exposure to increased estrogen levels, as is found in hormone replacement therapy for
menopausal women, can stimulate cell proliferation and lead to cancer.
People with suppressed immune systems can have an increased risk of cancer.
Since the immune system destroys cancer cells, a suppressed immune system will
increase the risk of cancer.
Exposure to oxygen increases cancer risk.
Reactive oxygen species, molecules which often normally occur, can cause mutations in
DNA.
Some lifestyle practices influence the probability of developing cancer.
Studies have shown that high fat diets and tobacco smoke can lead to increased cancer
risk while exercise can reduce the risk of cancer.
Exposure to radiation can cause cancer.
Ultraviolet light from the sun can lead to different types of cancer in skin.
Many, but not all, cancers are preventable.
Avoidance of certain behaviors can help prevent cancer.
12.6 Early detection and new treatments increase prospects for surviving cancer.
With research, new tests and treatments have been developed.
Cancer tests have increased the rates of early detection and cancer survival.
Physical exams and biopsies as well as mammograms and PSA tests are ways to detect
cancer. DNA tests can also be performed.
Traditional treatments include surgery, chemotherapy, and radiation therapy.
Surgery to remove tumors followed by chemotherapy or radiation therapy is a traditional
medical treatment for cancer.
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Research provides new approaches to the detection and treatment of cancer.
Development of new treatments such as herpecin and tamoxifen for breast cancer and
Rituximab for non-Hodgkin's lymphoma continue as more is understood about how
cancer cells function. Blocking growth factors and using antisense RNA are also
treatments in development.
12.7 How do you know? Assessing laetrile and other alternative cancer therapies.
Many alternative therapies exist, often without benefit of support by scientific studies.
Some alternative therapies are being studied and may prove effective.
Now you can understand. Does chemotherapy destroy the human immune system?
The effects of chemotherapy do affect the immune system, but impairment is meant to be
temporary.
Prevention is the best way to avoid cancer.
Avoiding behavior which increases cancer risk is the best way to avoid this disease.
Can vitamin supplements help prevent cancer?
Studies have not shown that vitamins are effective in preventing cancer.
What do you think?
The FDA is responsible for drug approval.
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