Cancer

Ray M. Merrill, PhD, MPH

Department of Health Science

Brigham Young University

Did you know?

In the United States… 1 in 3 people will develop cancer in their lifetime 1 in 8 women will develop breast cancer in their

lifetime 1 in 6 men will develop prostate cancer in their

lifetime Over 1,400,000 people will be diagnosed with

cancer this year Over 550,000 people will die from cancer this

year

Fifteen Leading Causes of Death, US, 2004

RankCause of Death Number of Deaths

Percent (%) of Total Deaths

Death Rate*

Source: US Mortality Public Use Data Tape, 2004, National Center for Health Statistics, Centers for Disease Control and Prevention, 2006.

1 Heart diseases 652,486 27.2 217.0

2 Cancer 553,888 23.1 185.8

3 Cerebrovascular diseases 150,074 6.3 50.0

4 Chronic lower respiratory diseases 121,987 5.1 41.1

5 Accidents (unintentional injuries) 112,012 4.7 37.7

6 Diabetes mellitus 73,138 3.1 24.5

7 Alzheimer disease 65,965 2.8 21.8

8 Influenza & pneumonia 59,664 2.5 19.8

9 Nephritis, nephrotic syndrome, & nephrosis 42,480 1.8 14.2

10 Septicemia 33,373 1.4 11.2

11 Intentional self-harm (suicide) 32,439 1.4 10.9

12 Chronic liver disease & cirrhosis 27,013 1.1 9.0

13 Hypertension & hypertensive renal disease 23,076 1.0 7.7

14 Parkinson disease 17,989 0.8 6.1

15 Assault (homocide) 17,357 0.7 5.9

All other & ill-defined causes 414,674 17.3

*Rates are per 100,000 population and age-adjusted to the 2000 US standard population.

United States 2007

From Jemal, A. et al. CA Cancer J Clin 2007;57:43-66.

What is cancer? Cancer is a collective name that refers to

a group of many diseases with one common characteristic: uncontrolled cell growth or loss of the cell's ability to perform apoptosis (cell suicide).

Mutations occur to genes that control the normal process of cell growth and death

Gradual increase in the number of uncontrolled dividing cells

Mass of tissue occurs called a “tumor” (also called a neoplasm)

Development of Cancer from genetically altered

cell to metastasis

Why do mutations happen?

Some cancer-causing mutations are simply spontaneous errors that appear in normal DNA molecules when cells duplicate their DNA prior to cell division

Some are related to environmental factors/exposures, diet, lifestyle choices or heredity (a few “suseptibility genes” passed down)

Accumulation of mutations in these 3 areas=cancer

The mutations that contribute to the development of cancer affect three general classes of gene: Oncogenes Tumor suppressor genes DNA repair genes

Cancer Tends to Involve Multiple Mutations

The formation of cancer usually requires multiple mutations, with the chance increasing for mutations to accumulate and cancer to develop with more years of life (Doll & Peto, 1981).

Heredity and Cancer

Cancer is not considered an inherited illness since 80 to 90 percent occur in people with no family history of the disease

E.g., only about 5 percent of breast cancers are thought to be due to inheritance of particular form(s) of a "breast cancer susceptibility gene."

Different Kinds of Cancer

Carcinomas Most common types of cancer Arise from the cells that cover external and internal body surfaces

Lung, breast, prostate, and colon are the most frequent cancers of this type in the United States

Sarcomas Arise from cells found in the supporting tissues of the body such as

bone, cartilage, fat, connective tissue, and muscle Lymphomas

Arise in the lymph nodes and tissues of the body's immune system Leukemias

Cancers of the immature blood cells that grow in the bone marrow and tend to accumulate in large numbers in the bloodstream

United StatesRates age-adjusted to the U.S. 2000 population

From Jemal, A. et al. CA Cancer J Clin 2007;57:43-66.

Prostate CancerRisk Factors

Age Race (African American=higher) Diet: high in calories Male Hormones Environmental Exposures A Vasectomy, BPH, STD’s Family History of Prostate Cancer

Tumor Grading/Staging

Microscopic examination also provides information regarding the likely behavior of a tumor and its responsiveness to treatment.

A low number grade (grade I or II) refers to cancers with fewer cell abnormalities than those with higher numbers (grade III, IV).

Why Cancer Is Potentially Dangerous

A malignant tumor, a "cancer," is a more serious health problem than a benign tumor because cancer cells can spread to distant parts of the body.

Cancer Detection and Diagnosis

Early detection affects the outcome of the cancer When cancer is found (type and how fast it is

growing) Invasion Metastasized

Early Cancer May Not Have AnySymptoms

Screening methods are designed to check for cancer in people with no symptoms. Some examples of screening methods are: Pap Test/smear Mammograms Blood Tests (PSA) Fecal Occult Blood Test (FOBT)

Diagnose the presence of cancer

Screening tests indicate the possible existence of cancer, a doctor must then perform a biopsy

For leukemias, a small blood sample serves the same purpose

Microscopic examination will tell the doctor whether a tumor is actually present and, if so, whether it is malignant (i.e., cancer) or benign.

Tumor Grading/Staging

Based on the answers to the following questions, the cancer is assigned a "stage." 1. How large is the tumor, and how far has it

invaded into surrounding tissues? 2. Have cancer cells spread to regional lymph

nodes? 3. Has the cancer spread (metastasized) to

other regions of the body?

Tumor grade and stage are related to cancer survival

What Causes Cancer?

Heredity? Behaviors? Other Factors?

In theory, differences in heredity or environmental risk factors might be responsible for the different cancer rates observed in different countries.

Tobacco Use and Cancer Cigarette smoking linked with cancer of the:

lung Mouth Larynx Esophagus Stomach Pancreas Kidney Bladder Cervix

Current estimates suggest that smoking cigarettes is responsible for at least one out of every three cancer deaths.

Tobacco Use in the US, 1900-2000

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*Age-adjusted to 2000 US standard population. Source: Death rates: US Mortality Public Use Tapes, 1960-2000, US Mortality Volumes, 1930-1959, National Center for Health Statistics, Centers for Disease Control and Prevention, 2002. Cigarette consumption: US Department of Agriculture, 1900-2000.

Per capita cigarette consumption

Male lung cancer death rate

Female lung cancer death rate

Smoking-Related CancersRelative Risks

Ex-smoker Current Smoker Lip & Oropharangyeal 1.76 4.55 Oesophageal 1.79 4.01 Stomach 1.11 1.41 Anal 1.83 3.18 Pancreatic 1.15 3.18 Laryngeal 2.86 7.48 Lung 6.75 M 13.0 M 5.07 W 11.4 F Cervix 1.31 1.75 Vulvar 1.37 3.42 Penile 1.6 1.8 Bladder 1.7 2.7 Renal Parenchymal 1.61 1.64 Renal Pelvic 1.95 3.96

Source: Single et al., Am J Public Health 1999;89:385-390.

Low-Strength Radiation

Some atoms give off radiation, which is energy that travels through space. Prolonged or repeated exposure to certain types of radiation can cause cancer.

High-Strength Radiation

X-rays or radiation emitted from unstable atoms called radioisotopes

Stronger than ultraviolet radiation Can penetrate through clothing and

skin and into the body High-strength radiation can cause

cancers of internal body tissues

Examples of Human Cancer Viruses

Viruses

A few viruses also can trigger the development of cancer

Cannot reproduce on their own Viruses are small infectious agents Enter into living cells and cause the

infected cell to produce more copies of the virus

Causes the cell to become malignant

Bacteria and Stomach Cancer

The bacterium H. pylori, which can cause stomach ulcers, has been associated with the development of stomach cancer

Breast cancer risk factors

Most common cancer in women and second to lung cancer in the number of cancer deaths among women

Causes/risk factors Heredity Long-term exposure to high blood levels of

estrogen Early onset of menstruation Late onset of menopause No children or first child after age 30 Obesity Current use of HRT Alcohol use

Inactivity Diet low in vegetables and fiber

Cancer Risk and Aging

Summary of What Causes Cancer

Source: CDC

30%

35%

15%

10%

7%3%

Diet & Physical Activity

Tobacco Use

Other Factors

Environmental & Occupational Factors

Sexual Factors Alcohol Overuse

Cancer Prevention

Many of the behaviors or exposures linked to cancer can be prevented

Ways to prevent cancer: Maintain a healthy weight; Eat no more than two or three servings of red meat per week; Take a multivitamin with folate every day; Drink less than one alcoholic drink a day; Eat five or more servings of fruits and vegetables per day; Eat more high fiber foods such as whole grains, wheat cereals, bread, and

pasta; Include cruciferous vegetables in your diet (such as broccoli, cabbage, etc.); Do not smoke; Protect yourself from the sun; Avoid certain workplace exposures; Protect yourself and your partner(s) from sexually transmitted infections; and Exercise regularly.

Quick Quiz 3pts/ques

1. What is the most common cancer for men, women?

2. Give 3 risk factors for the most prevalent male cancer

3. Give 3 risk factors for the most prevalent female cancer

4. What is the common characteristic that makes cells result in cancerous growth?

Quick Quiz cont.

5. What are the four main categories/kinds of cancer and describe what type of tissue that each arises from.

6. Compare benign vs malignant 7.Using no more than 5 sentences,

describe how a genetically altered cell becomes cancer that has spread throughout the body

8. Describe the I-IV grading/staging system for cancer

Quick Quiz, cont

9. How and to what extent does genetics play in the development of cancer?

10. List 3 ways cancers can be prevented