I. Cancer Cells
II. Causes and Prevention of Cancer
III. Prevention of Cancer
IV. Diagnosis of Cancer
V. Treatment of Cancer
I. Cancer Cells
A. The term "cancer" (a cellular disease) actually refers to over a hundred different diseases, but there are characteristics common to all cancer cells.
1a. Cancer cells lack differentiation: Nonspecialized cells that do not contribute to functioning of the body. Cells look distinctly abnormal.
(Insert breast cancer cell picture / http://www.dac.neu.edu/ http://rds.yahoo.com/_ylt=A0S0200GTFRIpQ4BbkqjzbkF/SIG=122m86262/EXP=1213570438/**http%3A//www.dac.neu.edu/barnett/Mem/Hancock.htm )
2a. Cancer cells have abnormal nuclei: enlarged and usually contains an abnormal number of chromosomes.
3a. Chromosomes are also abnormal: some portions of it may be duplicated, and some may be erased. Gene amplification (extra copies of specific genes) is much more common.
4a. Usually, cells with damaged DNA undergo apoptosis, or programmed cell death, but cancer cells fail to undergo this death cycle.
5a. Tissues that divide frequently are more likely to become cancerous.
6a. Unlimited replicative potential: Unlike normal cells that will divide about 60 times before they die, cancer cells are immortal and will therefore continuously divide, spreading the abnormalities.
7a. Telomeres: the special repetitive DNA sequences that chromosomes in human cells end with.
8a. Telomerase: the enzyme that can rebuild telomere sequences (allows for constant division of cells) rebuilds the telomeres in cancer cells.
9a. Cancer cells from tumors: Normal cells stop dividing when they come in contact with a neighbor. Cancer cells cannot do this; they pile up on top of one another and continually grow in layers. This forms a tumor.
10a. Benign tumor: encapsulated, does not invade adjacent tissues and therefore does not spread.
11a. Cancer cells do not respond to growth factors (the chemical signals that tell a cell when to divide, called stimulatory growth factors and inhibitory growth factors.)
12a. Carcinogenesis: development of cancer. Cancer cells gradually become abnormal because it is a multistage process divided into three stages:
- Initiation: Single cell mutates that causes it to divide repeatedly.
- Promotion: Tumor develops, and tumor cells keep dividing. As they divide, they mutate.
- Progression: Once a cell receives selective advantage over other cells by mutating, the process repeats several times, and eventually, a cell invades surrounding tissue and spreads.
13a. Cancer cells undergo angiogenesis and metastasis.
-Angiogenesis: the formation of new blood vessels. These vessels bring in nutrients and oxygen to a tumor.
- Metastasis: Cancer cells invade blood vessel or lymphatic vessel. Malignancy is present when cancer cells are found in nearby lymph nodes. Metastasis is when new tumors are formed far from the primary tumor. (Mader 404-405)
(Insert three phases of cancer development picture / Frolich PowerPoint slide 34)
B. Cancer is a genetic disease.
1b. Cyclin: molecule that must be present for a cell to proceed from interphase to mitosis. When cancer develops, the cell cycle repeats itself in a large part due to mutations in two types of genes: proto-oncogenes, and tumor suppressor genes. (Mader 405-406)
- Proto-oncogenes:products promote the cell cycle and prevent cell death (apoptosis). Proto-oncogenes that have mutated are cancer-causing genes called oncogenes.
- Tumor-suppressor genes: products inhibit the cell cycle and promote apoptosis. (Frolich PowerPoint slide 29)
2b. Growth factor: a signal that activates a cell-signal-pathway, resulting in cell division. Mader 406)
(Insert normal cells vs. cancer cells picture / Frolich PowerPoint slide 30)
1c. p53: protein that turns on genes to stop the cell cycle in order to activate repair enzymes. If repair can't happen, p53 promotes apoptosis. Many tumors lack in p53 activity.
1d. Tumor-suppressor genes become inactive when they mutate. (Mader 406)
C. Types of Cancers
1c. One in three americans will deal with cancer in their lifetimes.
2c. Oncology: study of cancer.
3c. Prognosis depends on whether the tumor has invaded surrounding tissues, and whether there are metastatic tumors in distant parts of the body.
4c. Tumors are classified by their place of origin.
- Carcinomas: cancer of the epithelial tissues and adenocarcinomas are cancers of glandular epithelial tissues. Includes cancer of skin, breast, liver, pancreas, intestines, lung, prostate, and thyroid.
(Insert carcinoma picture / http://www.flickr.com/ / http://www.flickr.com/photos/spally/405229981/)- Sarcomas: cancers that arise in muscles and connective tissue, such as bone and fibrous connective tissue.
(Insert sarcoma picture /www.visualsunlimited.com http://www.visualsunlimited.com/browse/vu205/vu205920.html)- Leukemias: cancer of the blood.
(Insert leukemia picture / http://www.resource4leukemia.com/ http://rds.yahoo.com/_ylt=A0S020qpW1RIH4oAeWmjzbkF/SIG=12dnv3q9o/EXP=1213574441/**http%3A//www.resource4leukemia.com/topics/photogallery.html )- Lymphomas: cancer of lymphatic tissue. (Mader 406-407)
(Insert colonic lymphoma picture / http://www.gastrointestinalatlas.com/ / http://www.gastrointestinalatlas.com/English/Colon_and_Rectum/Colon_Lymphoma/colon_lymphoma.html)5c. Common cancers: lung cancer is most common in respiratory system. Also a common form of cancer, and risks are much more increased for those who smoke. In digestive system, colon / rectum cancer is common. Also, cancer of the pancreas, stomach, esophagus, and other organs are somewhat common. Cardiovascular, cancers include leukemia and plasma cell tumors. Lymphatic, cancers are Hodgkin or non Hodgkin lymphoma. Endocrine, thyroid. Central, brain and spinal tumors. Breast cancer is amongst the most common types. Reproductive, cervix, ovary and prostate cancer are most common. Urinary, bladder and kidney cancer. Skin, melanoma and basal cell carcinoma. (Mader 407)
(Insert lung cancer picture / http://www.dogflu.ca/ http://www.dogflu.ca/07162006/12/blood_test_detects_lung_cancer)
II. Causes and Prevention of Cancer
A. Genetics / Hereditary: 1990- 1st gene associated with breast cancer was discovered. Cancer develops wherever the second mutation in the copied gene occurs. (Mader 408) In other words, mutations of these genes predispose individuals to certain cancers but it takes at least one more acquired mutation during their lifetime to develop cancer. (Frolich PowerPoint slide 33)
1a. Examples of genes associated with cancer:
–BRCA1 and BRCA2 – tumor-suppressor genes that are associated with breast cancer
–RB – a tumor-suppressor gene that is associated with an eye tumor
–RET – proto-oncogene that is associated with thyroid cancer (Frolich PowerPoint slide 33)
B. Environmental Carcinogens:
1b. Mutagen: Agent that causes mutation.
2b. Carcinogen: chemical that causes cancer by being mutagenic.
3b. Heredity can predispose a person to cancer, but environment mutagens is what decides whether it will develop. (Mader 408)
4b: Radiation: Ionizing radiation (ultraviolet light), radon gas (natural breakdown of uranium in soil, rock and water) is the second-leading cause of lung cancer, nuclear fuel (ie., nuclear bomb explosion), and x-rays can affect DNA and cause mutations. Ultraviolet radiation in sunlight and tanning lamps probably account for the increase in skin cancer. Melanoma skin cancer is responsible for 1-2% of total cancer deaths in the US.
5b. Organic Chemicals: synthetic organic chemicals.
- Tobacco smoke: number of organic chemicals that are known mutagens. The number of cigarettes smoked per day and age started contribute to cancer development. Scientists estimate that 80% of all cancers are related to the use of tobacco. When tobacco is mixed with alcohol, chances are increased.
- Pollutants: Metals, dust, chemicals, pesticides and other pollutants increase the risk of cancer.
- Viruses: at least 4 types are believed to cause cancer: hepatitis B and C, Epstein-Barr virus, and human papillomavirus. (Mader 409)
III. Prevention of Cancer
A. Don't smoke, don't sunbathe, avoid alcohol, avoid radiation, be tested for cancer, be aware of occupational hazards, be aware of postmenopausal hormone therapy, get vaccinated, avoid obesity, eat plenty of high-fiber foods, increase consumption of foods rich in vitamins A and C, reduce consumption of salt-cured, smoked, or nitrite-cured foods, include vegetables from the cabbage family in your diet, and be moderate in the consumption of alcohol, if you do drink. (Mader 410)
IV. Diagnosis of Cancer
A. Seven Warning Signs:
Change in bowel or bladder habits
A sore that does not heal
Unusual bleeding or discharge
Thickening or lump in breast or elsewhere
Indigestion or difficulty in swallowing
Obvious change in wart or mole
Nagging cough or hoarseness (Frolich PowerPoint slide 35)
- Self-examination – monthly exams of breasts and testicles starting at age 20
- Colonoscopy – every 5 years starting at age 50
- Mammogram – yearly after age 40
- Pap smear – should begin these 3 years after vaginal intercourse or no later than age 21
(Frolich PowerPoint slide 36)
C. Detecting skin cancer: Follow the ABCDs!
•A – asymmetry
•B – border is irregular
•C – color varies from one area to another
•D – diameter is larger than 6mm
(Insert detecting melanoma picture / Frolich PowerPoint slide 38)
C. Tumor Marker Tests
1c. Blood tests that look for antigens / antibodies. Tumors release substances that provoke and antibody response. If the number of specific antibodies is high, it can point to cancer already in the body.
D. Genetic Tests
1d. It is possible to detect the likelihood of cancer before a tumor even appears through tests that look for genetic mutation in proto-oncogenes and tumor-suppressor genes. These tests can signal the possibility of colon, bladder, breast, and thyroid cancers, as well as melanoma.
2d. These tests can also be used to determine if cancer cells still remain after the removal of a tumor.
3d. Telomerase, the enzyme that keeps telomeres a constant length in cells, is not active in normal cells but is in cancer cells. So, testing for the presence of telomerase is accurate in determining a cancerous cell. (Mader 414)
(insert telomerase picture / http://www.postech.ac.kr/ http://www.postech.ac.kr/lab/chem/sbpc/contents/research/structure.htm
V. Treatment of Cancer
A. Standard:
•Surgery – removal of small cancers (those in situ) Danger: difficult to guarantee you'll remove all of the cancerous cells.
•Radiation therapy – localized therapy that causes chromosomal breakage and disrupts the cell cycle. Dividing cells are more susceptible to the effects. Proton and neutron beams also work well.
•Chemotherapy – drugs that treat the whole body that kills cells by damaging their DNA or interfering with DNA synthesis. Treats the entire body.
•Bone marrow transplants – transplant bone marrow from one individual to another, usually in conjunction with chemotherapy. (Frolich PowerPoint slide 40) and (Mader 415)
B. Newer Therapies
•Immunotherapy – When cancer develops, the immune system has failed to dispose of cancer cells. This therapy injects immune cells that are genetically engineered to bear the tumor’s antigens. When returned to the body, they help cytokines and present the antigen to T cells, which then destroy tumor cells in the body.
•Passive immunotherapy – antibodies that are linked to radioactive isotopes or chemotherapeutic drugs are injected into the body. Some of the antibodies are designed to focus on the receptor proteins of cancer cells.
•p53 gene therapy – a retrovirus in clinical trial that is injected into the body where it will infect and kill only tumor cells (cells that lack p53 = tumor cells).
•Angiogenesis inhibition - Angiostatin and endostatin are drugs in clinical trials that appear to inhibit angiogenesis.
(Frolich PowerPoint slide 41) and (Mader 416)
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