Chapter 16

Cancer Leading cause of disease-related death

among people under age 75 Second leading cause of death Evidence supports that most cancers

could be prevented by simple lifestyle changes

Tobacco is responsible for about 30% of all cancer deaths

Poor diet and exercise habits account for another 30% of cancer deaths

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Figure 16.1 Percentage of all cancer deaths linked to risk factors

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What is Cancer? Definition: An abnormal and uncontrolled

growth of cells that can lead to death Tumor: A mass of tissue that serves no

physiological purposeBenign tumor: Mass of cells enclosed in a

membrane that prevents their penetration of other tissues

Malignant tumor: Can invade surrounding tissues

Every case of cancer begins as: a genetic change in a cell that allows it to grow and divide when it should not

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Figure 16.2 Tumor development occurs in stages

Metastasis Definition: The spread of cancer cells from one part of the body to another

Primary tumor: original location of cancer

Secondary tumors (metastases) : New tumors

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Stage Description

0 Early cancer, present only where it originated

I More extensive

II Greater tumor size

III Cancer has spread to nearby lymph nodes/adjacent organs

IV Advanced cancer; spread to other organs

Types of Cancer Classified according to types of cells

that give rise to themCarcinomas –Sarcomas –Lymphomas-Leukemias -

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The Incidence of Cancer American Cancer Society

Estimates:5-year survival rate for all cancers

diagnosed between 1995 and 2005 is 68% (excludes~ 1 million curable types of skin cancer)

At current rates, its estimated that1 in 2 men and 1 in 3 women will develop cancer during their lifetime

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The Incidence of Cancer

American Cancer Society Estimates:90% of skin cancer could have been

prevented by protecting the skin from the sun

87% of lung cancer could have been prevented by avoiding exposure to tobacco smoke

Regular screening and self-examinations could save an additional 100,000 lives per year

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Lung Cancer Most common cause of cancer related

death in the U.S.157,000 deaths

Risk factorsTobacco smoke (including ETS)

contributes to 90% of lung cancer deaths

Detection Difficult to detect earlySymptoms do not appear until invasive stageSymptoms: Persistent cough, chest pain, or

recurring bronchitisDiagnosis: CT scan (earlier?), chest x-ray or

sputum examination, bronchoscopy11

Lung Cancer Treatment

If caught early, localized cancers can be treated with surgery Only 15% detected prior to spreading so, Radiation and chemotherapy are used in

addition to surgery For cases detected early, 53% of patients

are alive 5 years post-diagnosisOverall, the 5-year survival rate is only

15%

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Colon and Rectal (Colorectal)Cancer

Third most common type of cancer Risk factors

Age (91% of cases occur in people 50 or older)

Heredity, genetic propensity to develop polyps

Diet, smoking, excessive alcohol use and obesity

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Detection and treatmentRegular screening tests are recommended beginning at age 50

Symptoms: bleeding from rectum and changes in bowel habits

Treatment Primarily SurgeryRadiation and chemotherapy can be used

Colon and Rectal Cancer

Breast Cancer Most common cancer in women

Causes almost as many deaths in women as lung cancer

Risk factorsStrong genetic factor:Age: Most common in women over 50

Early onset of menstruation First child after 30Current use of HTUnhealthy diet and lifestyle

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Breast Cancer Early detection

ACS recommends 1 mammogram/year (women over 40)

Clinical and Self breast exams (starting at age 20)

Symptoms may include a lump, changes in size, dimpled, redness or scaliness of nipple or breasts,

Treatment Ultrasonography and biopsy to

determine if cancerous If the tumor is discovered before

it has spread, patient has 98% chance of surviving more than 5 yrs.

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Breast Cancer

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Prostate Cancer Most common cancer in men

Risk factors Age( more than 60% of cases diagnosed in men over 65)

Genetic predispositionDiet and Lifestyle African American and Jamaican men have highest rates in the world

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Prostate Cancer Detection

Blood test: Prostate-specific antigen (PSA)

Rectal exam:Symptoms may include changes in urinary frequency, weak/interrupted urine flow, painful urination and blood in urine

Treatment Surgical removal of the prostate and radiation (depends on stage and age)

Radioactive seeds5-year survival rate is nearly 100%

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Cancers of the Female Reproductive Tract

Cervical cancer Most cases stem from human papillomavirus (HPV) infection (STD)

PreventionThe PAP test is a highly effective

screening test for this cancer All sexually active women ages 18-

65 should be tested regularly Gardasil

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Skin Cancer Types of skin cancer

Basal cell carcinomasSquamous cell carcinomasMelanoma (most serious type of skin cancer

Most common form of cancer1 million cases per year (68,000 are melanoma)

Risk factorsExcessive exposure to UV raysCommon causes are sunburns and suntansCaucasians are 10X more likely than African

Americans to develop basal and squamous cell carcinoma

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PreventionAvoid long term overexposure to sunlight

Detection of MelanomaABCD screen test

Skin Cancer

The Causes of Cancer The role of DNA (Deoxyribonucleic acid)

Each cells has 23 pairs of chromosomes Gene: Smaller unit of DNA

DNA mutations and cancer Mutagens: Radiation, certain viruses and chemical

substances Oncogenes: A gene in which mutations are

associated with the transformation of a normal cell into a cancer cell

Tumor suppressor gene: Type of oncogene that normally restricts cellular growth

Hereditary cancer risks BRCA1 gene

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The Causes of Cancer Cancer promoters

Definition: Do not directly produce mutations, they instead accelerate the growth of cells without damaging or permanently altering the DNA Estrogen is an example

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Dietary Factors Food choices affect your cancer risk by:

exposing you to potentially dangerous compounds and depriving you of protective compounds

Dietary fat and meat Diets high in “bad” fats and meat may

contribute to colon, stomach, and prostate cancers

Omega-3 fats are healthier for body Alcohol

Risk of oral and colon cancer Fried foods Fiber Fruits and vegetables

Phytochemicals Inactivity and obesity

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Carcinogens in the Environment

MicrobesAbout 15% of the world’s cancers are caused

by microbes Ingested chemicals

Nitrosamines: Nitrates and nitrites found in processed meats that combine with dietary substances and become highly potent carcinogens

Environmental and industrial pollution Radiation

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Figure 16.8 The seven major warning signs of cancer

Preventing Cancer Lifestyle choices

Avoid tobaccoControl diet and weightRegular exerciseProtect skin from the sunAvoiding environmental and

occupational carcinogensFollow recommendations for cancer

screenings

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