Download Powerpoint Ch 13

Chapter 13
Cancer:
Understanding
Risks and Means
of Prevention
Cancer: Understanding Risks
and Means of Prevention
• Learning Objectives
1. Identify and describe the most important ways
to prevent cancer.
2. Briefly discuss the incidence of cancer today
and why mortality has not fallen.
3. Define the following terms: cancer, tumor,
benign tumor, or, metastasis, and
xenoestrogen.
4. Explain the difference between inherited
diseases and genetic diseases.
Cancer: Understanding Risks
and Means of Prevention
• Learning Objectives (continued)
5. Describe the kinds of environmental agents
that cause cancer.
6. Explain ways to prevent skin cancer.
7. Discuss some risk factors associated with
breast cancer.
8. Describe how to do a breast self-exam (BSE).
9. Describe how cigarette smoke contributes to
cancer.
Cancer: Understanding Risks
and Means of Prevention
• Learning Objectives (continued)
10. Discuss the association between diet and
cancer.
11. Briefly describe the three medical treatments
for cancer.
12. Describe several coping mechanisms for
someone with cancer.
13. Explain the risks and benefits of being tested
for cancer susceptibility gene.
Cancer: Understanding Risks
and Means of Prevention
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Understanding Cancer
Causes of Cancer
Environmental Factors that Cause Cancer
Facts About Common Cancers
Diet and Cancer Risk
Cancer Treatments
Cancer: Understanding Risks
and Means of Prevention
• 1 in 2 men and 1 in 3 women will develop
some form of cancer in their lifetimes.
• Each year nearly 600,000 Americans die
from cancer.
• Half of all cancer cases can be cured if
detected early.
Cancer: Understanding Risks
and Means of Prevention
• Most cancers are preventable with a healthy
lifestyle.
– Avoid cigarette smoke and tobacco in any form.
– Maintain a healthy weight and be physically
active.
– Maintain good nutrition.
Understanding Cancer
• “Cancer” is from the Latin word meaning
crab.
– Cancer is unregulated multiplication of
specific cells in the body.
– A tumor develops when a normal body cell
grows abnormally and reproduces too
rapidly.
– Benign tumors do not spread to other parts
of the body.
– Malignant tumors are composed of cells that
multiply rapidly, have abnormal properties,
and invade other normal tissue.
Understanding Cancer
• The cells of most malignant tumors undergo
metastasis, a process where the cells detach
from the original tumor, enter the lymphatic
system and bloodstream, and are carried to
other organs.
• Watch Understanding Cancer 5 min
Understanding Cancer
• Cancers are medically classified according to the
organ or tissue in which the tumor originates.
– Carcinomas begin in the skin or tissues that line the
internal organs
– Sarcomas develop in the bone, cartilage, fat, muscle or
other connective tissues.
– Leukemias begin in blood and bone marrow
– Lymphomas start in the immune system
– Central nervous system cancers develop in the brain
and spinal cord.
Understanding Cancer
• Fifty percent of all human cancers originate in
one of four organs:
– Lungs
– Breast
– Prostate
– Colon
• Biopsy—once a tumor is detected, cells can be
removed from it using this procedure
Understanding Cancer
• Stages of Cancer
• Stage I: Cancer cells can be distinguished from
normal cells.
• Stage II: Cancer cells begin to metastasize and may
migrate to nearby lymph nodes.
• Stage III: Cancer cells have spread throughout the
body and tumors may have started to grow in other
organs.
• Stage IV: Often a terminal stage; tumors are found
throughout the body and usually are resistant to
treatment.
Watch Breast C staging 2min
Understanding Cancer
Number of
Deaths
Causes of Cancer
• 90–95% of all cancers are not inherited
from parents.
• A persistent fear of developing cancer can
generate stress that may weaken the
immune system and contribute to the
development of disease, including cancer.
• Genes can be altered by environmental
agents, which transform cells into cancer
cells. Cancer is a genetic disease but not an
inherited disease.
Causes of Cancer
• Studies on identical twins show that most of
the time cancer is not an inherited disease.
• Cancer Susceptibility Genes
– Are extremely rare, 5% to 10% of all cancers.
– Makes a person more vulnerable to
environmental factors that contribute to the risk
of developing cancer.
– Being identified as a carrier does not guarantee
that you will have cancer
Causes of Cancer
Cancer Development
Environmental Factors
That Cause Cancer
• It is difficult to pinpoint a single cause of
cancer, but certain environmental factors are
strongly associated with the occurrence of
particular cancers.
• Epidemiological studies show that 80% to
90% of cancers are caused by exposure to
environmental factors known to increase the
risk of cancer.
– For example, smoking cigarettes = 10–20 times
higher risk later in life.
Environmental Factors
That Cause Cancer
Environmental Factors
That Cause Cancer
• Three Classes of Environmental Agents
– Ionizing radiation
– Infectious microorganisms
– Cancer-causing chemicals (chemical carcinogens)
Environmental Factors
That Cause Cancer
Environmental Factors
That Cause Cancer
• Three Classes of Environmental Agents
Ionizing Radiation
• X-rays, UV light, radioactivity whose energy can
damage cells and chromosomes
• UV Light—UVA and UVB wavelengths are both
dangerous
Environmental Factors That Cause Cancer
• Three Classes of Environmental Agents
(continued)
– Infectious Microorganisms
• “Tumor viruses”—only a few viruses have been associated
with human cancers; in most people, these viruses will not
cause cancer.
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Hepatitis B and C (liver cancer)
Papillomavirus (genital and cervical cancers)
Human T cell leukemia-lymphoma virus (leukemia and lymphoma)
Epstein-Barr virus (cancer of the nose or pharynx)
HIV (Kaposi’s sarcoma)
H. pylori (gastric cancer, lymphoma, and possibly pancreatic cancer)
Environmental Factors That Cause Cancer
• Three Classes of Environmental Agents
Chemical Carcinogens
• Environmental chemicals that can interact with cells
to initiate cancer:
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Tobacco
Pesticides
Asbestos
Heavy metals
Benzene
Nitrosamines
Environmental Factors That Cause Cancer
Environmental Factors That Cause Cancer
• Three Classes of Environmental Agents
Chemical Carcinogens
• Mesothelioma: a rare form of lung cancer that only
occurs among persons exposed to asbestos fibers.
• Industry exposure risk is low compared to tobacco
and diet.
Environmental Factors
That Cause Cancer
• Do Xenoestrogens Cause Cancer?
– Xenoestrogens are chemicals found in the
environment that mimic estrogen and aid in the
development of cancer, specifically breast
cancer.
– Substances that contain xenoestrogens:
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DDT
Pesticides
Polychlorinated biphenyls (PCBs)
Bisphenol-A (BPA)
Gasoline vapor
Environmental Factors
That Cause Cancer
• Do Xenoestrogens Cause Cancer?
Eating broccoli, cabbage, and soy products
may help counteract the effects of
xenoestrogens.
Facts About Common Cancers
• Lung Cancer
– Lung cancer causes more deaths among men
and women than any other form of cancer does.
– Accounts for 15% of all cancers.
– Lung cancer could be almost completely
prevented if people would stop (or never start)
smoking.
• Main cause of nearly 90% of lung cancers.
– Lung cancer rate is increasing in other nations.
Facts About Common Cancers
• Breast Cancer
– Both men and women can develop breast
cancer, but it occurs very rarely among men.
– Factors that have been proposed as contributing
to the increased rate of breast cancer include:
• Increased weight
• Less exercise
• Increased dietary fat
Facts About Common Cancers
• Breast Cancer (continued)
– Other factors that increase risk:
• Having a mother who had breast cancer before age
60.
• Experiencing menarche before age 14.
• Having your first child after age 30 or having no
biological children.
• Experiencing menopause after age 55.
• Having benign breast disease.
Facts About Common Cancers
• Breast Cancer (continued)
– Other factors that increase risk:
• Having estrogen replacement therapy after age 55.
• Consuming more than 3 ounces of alcohol per day.
• Having inherited BRCA1 or BRCA2 genes.
Facts About Common Cancers
• Breast Cancer (continued)
– Ways to prevent and detect breast cancer:
• 10% of women in industrialized countries will get
breast cancer.
• Living healthfully—maintaining normal body weight,
low-fat diet, consuming adequate fresh fruits and
vegetables, engaging in physical activity, and limiting
alcohol consumption.
Facts About Common Cancers
• Breast Cancer (continued)
– Ways to prevent and
detect breast cancer:
• Monthly breast
self-exams beginning
at age 20.
• Mammograms every 1 to 2 years for
women in their 40s.
• The drug tamoxifen can be used for
breast cancer treatment as well as for
protection.
Facts About Common Cancers
• Testicular Cancer
– Rate had been increasing in young men,
possibly because of exposure to
xenoestrogens.
– Fairly rare and can be cured if detected early.
Facts About Common Cancers
• Prostate Cancer
– Prostate cancer occurs mostly in men over age 65.
– Early diagnosis relies on two tests:
• Finger rectal exam
• Prostate-specific antigen test (PSA)
– Detects a protein in blood that is associated with abnormal
growth of the prostate gland.
– This cancer develops very slowly.
– The U.S. Preventive Services Task Force
recommends against any routine screening for
prostate cancer.
Facts About Common Cancers
• Skin Cancer
– Melanoma is a
malignant form of skin
cancer.
– It is the fifth most
frequently diagnosed
cancer among
Americans.
– Exposure to sunlight is
the primary cause of all
forms of skin cancer.
Facts About Common Cancers
• Skin Cancer (continued)
– Most common cancer in women ages 25–29 and
the second most common in women ages 30–34.
– Having dark skin makes a person 500 times less
likely to get melanoma.
Facts About Common Cancers
• Skin Cancer (continued)
– Basal cell carcinoma and squamous cell carcinoma
are usually not life-threatening.
– Abnormal cells can be removed by:
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Surgery
Scraping
Freezing
Burning
Facts About Common Cancers
• Skin Cancer (continued)
– Remember the “ABCD” rules when
examining your skin for moles that could be
melanoma:
• Asymmetry
• Border
• Color
• Diameter
Facts About Common Cancers
• Colorectal Cancer
– Colorectal cancer affects men and women equally.
– It causes about 50,000 deaths annually in the
United States.
– Screening includes occult blood tests (stool
sample), flexible sigmoidoscopy, and
colonoscopy.
– Certain inherited genes are known to increase risk
of colorectal cancer.
Diet and Cancer Risk
• Many studies show that diet is associated
with cancer.
• Certain dietary choices may help prevent
cancer, such as increased consumption of B
vitamins, vitamin C, and folic acid.
• Scientists speculate that the human body
may not be capable of digesting modernday processed foods, leading to an
accumulation of toxic chemicals that may
cause cancer.
Diet and Cancer Risk
Cancer Treatments
• Three Medical Treatments for Cancer
– Surgery to remove the tumor (best option).
– Radiation therapy to destroy cancer cells.
– Chemotherapy, or the use of toxic chemicals
(drugs) to kill cancer cells.
– There are also many cancer drugs.
• Most are very expensive.
Other Cancer Treatments
Cancer Treatments
• Curing Childhood Cancers
– There are 20,000 new child cancer patients every
year.
– 80% are cured and live to adulthood.
– Many have ongoing medical problems.
Cancer Treatments
• Cancer Vaccines
– HPV
– Hepatitis B
– Medical researchers are currently working on
developing more anticancer vaccines.
Cancer Treatments
• Coping with a Diagnosis of Cancer
– Coping can be difficult because of:
• Denial on the part of the patient or family
• The need for surgery or other treatment
• The need to face death of the patient
– The coping strategies for dealing with the
emotional distress of many chronic or fatal
illnesses are similar.
– Coping with cancer requires conviction, courage,
and belief that a cure is possible.
Cancer: Understanding Risks
and Means of Prevention
• What things are you doing that help decrease
your risk of getting cancer?
• What are you going to add to your life that will
further help decrease your risk?