Chapter12

Cancer Prevention

Chapter 12

Objectives

• Define cancer and understand how it starts and spreads.

• Cite guidelines for preventing cancer.• Delineate the major risk factors that lead to

specific types of cancer.• Assess the risk for developing certain types

of cancer.• Learn everyday lifestyle strategies that you

can use immediately to decrease overall cancer risk.

Cancer Prevention

Cancer Terms

• Deoxyribonucleic acid (DNA)

• Ribonucleic acid (RNA)

• Oncogenes– genes that initiate cell division

• Suppressor Genes– genes that deactivate the process of cell

division

Cancer Prevention

Cancer Terms

• TumorBenign

Not active

MalignantActive growth; cancerous

• Carcinoma in situ– Tumor growth reaches about 1 million cells

Cancer Prevention

Cancer Terms

• Chromosome segments called telomeres erode each time the cell replicates and divides– Human tumors make an enzyme known as

telomerase– Keeps the chromosome from running out of telomeres

entirely– Allows cells to reproduce indefinitely, creating a

malignant tumor.– May keep old cancer cells from dying

Cancer Spread

• The tumor requires more oxygen and nutrients to grow.– A few of the cancer cells start producing

chemicals that enhance angiogenesis• capillary (blood vessel) formation into the tumor

– Angiogenesis is the precursor of metastasis• Metastasis - cancerous cells now can break away

from a malignant tumor and migrate to other parts of the body, where they can cause new cancer.

How Cancer Starts & Spreads

Incidence of Cancer

• Cancer is the second leading cause of death in the US

1. Almost 23% of all deaths the US are caused by cancer.2. Tobacco use is responsible for 87% of lung cancer deaths.3. Death rates for most major cancer sites are declining, except lung

cancer in women 4. In 2008:

a. About 570,000 Americans died from cancer.b. Approximately 1.4 million new cases were diagnosed.

• Largely preventable.– As much as 80% of all human cancer is related to lifestyle or

environmental factors (Figure 12.7; Acetate 76).– Individuals with healthy lifestyles have a lower incidence of

cancer

Incidence of Cancer

Cancer Incidence & Death Rates

Relative Roles of Cancer-Causing Factors

Healthy Lifestyle and Cancer Mortality

Guidelines for Preventing Cancer (intro.)

Become Health Educated Make Dietary Changes

a.Predominantly vegetarianb.High in fiberc.Low in fat (particularly from animal sources)d.Encourage cruciferous vegetables, tea, soy products,

calcium, and omega-3 fatse.Keep protein intake within the recommended nutrient

guidelinesf. Use alcohol in moderation – if it is usedg.Avoid obesity

• Antioxidantsa.Absorbs free radicals

Tips for a Healthy Cancer-Fighting Diet

Guidelines for Preventing Cancer (intro.)

• Phytonutrients • Compounds, found in abundance in fruits and vegetables,

apparently prevent cancer by blocking the formation of cancerous tumors and disrupting the process at almost every step of the way

• Removing carcinogens from cells before they cause damage. • Many traditional spices contain cancer fighting phytonutrients.

Guidelines for Preventing Cancer (intro.)

• Fiber has been associated with lower colon cancer.

• Drink Tea• Polyphenols

• Too much Dietary fat may promote cancer and excessive weight.

• Avoid processed meat and excessive animal protein

• Soy • Isoflavones

Guidelines for Preventing Cancer (intro.)

•Abstain from tobacco• Tobacco is responsible for more than 435,000 deaths in the US and 5

million deaths worldwide annually.• The life expectancy of a chronic smoker is 15 years shorter than for a

nonsmoker.

•Avoid excessive sun exposure• Too much ultraviolet radiation is a major contributor to skin cancer.

• Ultraviolet A rays (UVA) – sun lamp radiation is linked to melanoma.

• Ultraviolet B rays (UVB) – cause sunburn and all 3 types of skin cancer.

• The 3 types of skin cancer are:• Basal cell carcinoma.• Squamous cell carcinoma.• Malignant melanoma – 8,650 deaths in 2009.

Warning Signs of Melanoma

Self-Exam for Skin Cancer

Guidelines for Preventing Cancer (intro.)

•Monitoring estrogen, radiation exposure, and potential occupational hazards• Engaging in physical activity

• Early detection• BSE and TSE

Breast Self-Examination

Testicular Self-Examination

Warning Signals of Cancer

Change in Bowel or Bladder Habits A Sore that Does Not Heal Unusual Bleeding or Discharge Thickening or Lump in Breast/Elsewhere Indigestion or Difficulty Swallowing Obvious Change in Wart or Mole Nagging Cough or Hoarseness

Cancer Promoters

What Can You Do? Follow Healthy Lifestyle Habits Learn About Cancer Signs Perform Early Detection See your Physician for Any Risk Factor