Cancer 101: A Cancer Education and Training Program for

[Target Population]

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Presented by:

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Presenter 2

The Role of Genes in Cancer

Cancer 101

Learning Module 4

Learning Objectives

At the completion of learning Module 4, you will be able to:

• Describe the role genetics plays in our lives• Describe what is meant by the term “gene”• Describe what genes do• Describe what a gene mutation is• Describe how a genetic mutation might affect

health and the development of cancer

Learning Objectives (cont’d)

• Describe how a genetic condition can be acquired or inherited

• Discuss what a genetic consultation is

• Describe the benefits and limitations of genetics testing

• Discuss the benefit of recording your family health history

Genetics

• Refers to the study of genes

• Plays a role in health and disease

• Tracing your family history can help you and your doctor determine risk and take action to keep your and your family healthy

Where are genes found?

Gene

All Living Things Contain DNA

SOURCE: National Human Genome Research Institute

All The Information Necessary

SOURCE: National Human Genome Research Institute

DNA is organized into genes

SOURCE: National Human Genome Research Institute

The Same DNA

All of the cells in an individual contain the same exact genetic information.

“On” and “Off”

Different sets of genes are turned “on” and “off” in different types of cells

A closer look at DNA

SOURCE: National Human Genome Research Institute

Are Individuals Unique?

SOURCE: National Human Genome Research Institute

Chromosomes

• Vary in number among different living things.

• Help ensure DNA is accurately copied and distributed during cell division.

• Changes in number or structure in new cells may lead to serious problems.

Interaction with Environment

SOURCE: National Human Genome Research Institute

What is a gene mutation?• Any permanent

change in the DNA of a cell.

• Can be acquired, in which case they are caused by:– Harmful environmental

exposures– Aging– Mistakes during cell

division

• Can be hereditary

How are mutations inherited?

• Hereditary mutations are carried in the DNA of reproductive cells.

• When reproductive cells containing mutations combine to produce offspring, the mutation will be in all of the offspring’s body cells.

How do mutations affect us?

• Most disease begin in our genes.

• If DNA repair fails in a cell, mutations can be passed on to future copies.

• Gene mutations can have a latent effect, or even a positive effect.

• The ability to identify a gene mutation is possible through genetic testing.

Genetic conditions among ethnic groups

What is genetic testing?

• Gene testing involves examining a person's DNA for mutations linked to a disease or disorder.

• DNA typically taken from cells in a sample of blood.

• Test can tell if mutation is present, but not if disease will develop.

How is genetic testing used in studying cancer?

• In studying cancer, gene testing can be used to: – estimate risk of certain cancers,– diagnose some types of cancer, – classify cancer into subtypes, or – predict a patient's responsiveness to new

treatments.

Benefits of genetic testing

• Poses minimal physical risk• Negative result can:

– cause relief – eliminate need for frequent check-ups and tests

• Positive result can:– relieve uncertainty – allow a person to make informed decisions about the

future– give person chance to take steps to reduce risk

before disease develops

Limitations of genetic testing• Disorders that “run in families” can be traced to

shared environmental exposures rather than inherited susceptibility.

• Mutations detected by a positive test may never lead to disease.

• Existing tests look for more common gene mutations, many disease-causing mutations may escape.

• Positive result may not have adequate treatment.• Positive result can have adverse psychological

consequences.• Positive result can affect family and personal

relationships.

Genetic Information Nondiscrimination Act of 2008

• Protects a person’s confidentiality regarding gene test results.

• Prohibits insurance companies and employers from discriminating against individuals based on knowledge of differences in their DNA that may affect their health.

Image Source: National Human Genome Research Institute

Family Health

• Family members share genes, behaviors, lifestyles and environments.

• Having a close family member with a chronic disease may increase your risk of developing that disease.

Image Source: National Human Genome Research Institute

Family Health History

• Written or graphic record of the diseases and health conditions present in your family.

• Useful tool for understanding health risks and preventing disease in individuals and their close relatives.

Family History Information

Important to collect:• Gender• Date of birth• For deceased relatives, age at time of death and

cause of death• Disease or other medical conditions• Age of disease onset• Diet, exercise habits, smoking habits, or history

of weight problems• Ancestry

Which diseases are important to track?

• Alcoholism• Arthritis• Asthma• Birth defects• Cancer• Diabetes• Hearing loss• Heart disease• High blood pressure

• High cholesterol• Learning disabilities• Kidney disease• Mental illness• Mental retardation• Miscarriages or

stillbirths• Stroke• Substance abuse• Vision loss

Determining Your Risk

Patterns in a family history that may indicate a higher risk:

• More than one blood relative with a particular disease

• Diagnosis at an earlier age than expected

• Diseases that are rare in a certain gender

• Recurring combinations of diseases

Surgeon General’s Family History Initiative

• A national campaign to encourage Americans to learn more about their family history

• My Family Health Portrait http://familyhistory.hhs.gov

http://understandingrisk.cancer.gov/

This site provides reliable information on cancer risk:– What it means– What we know about

contributors to risk– What you can do

about it

Case Study• Martha heard about the Surgeon General’s

Family History Initiative and decided to discuss family history with her relatives at their family reunion.

• After a great deal of conversation, Martha learned that her mother and grandmother had both been diagnosed with breast cancer.

• Martha is wondering if this might mean she could be at higher risk for breast cancer.

Case Study (cont’d)

• Martha wonders whether she should talk to her doctor about genetic testing.– What would be some of the benefits of genetic

testing?– What would be some of the limitations or risks

of genetic testing?

Research for the future…

Genetics has the power to improve the lives of patients through:

• Targeted therapy• Gene therapy• Personalized

medicine

Image Source: National Human Genome Research Institute

Targeted Therapy

• Blocks the growth and spread of cancer by interfering with specific molecules involved in tumor growth and progression.– Gleevec for certain kinds of leukemia– Herceptin for certain types of breast cancer

Gene Therapy

SOURCE: National Human Genome Research Institute

Personalized Medicine• Goals:

– Identify genetic differences between people that affect drug response

– Develop genetic tests that predict an individual’s response to a drug

– Tailor medical treatments to the individual• Increase effectiveness• Minimize adverse side effects

Image Source: National Human Genome Research Institute

In Summary

• You now have an understanding of:– Genes– What a gene mutation is and the role it could

play in your health and development– How gene mutations are acquired or inherited– What a genetic consultation is– The benefits and limitations of genetic testing– The importance of knowing about your family

health history