cancer

What is a tumor?

Abnormal cell proliferation.

What does proliferation mean?

Cell growth and division.

What is a benign tumor?

A localized, contained tumor that does not spread.

What does localized mean?

Staying in one area.

What is a malignant tumor?

A cancerous tumor that invades and can spread.

What is metastasis?

The spread of cancer cells to other parts of the body.

What is the main difference between benign and malignant tumors?

Benign tumors stay contained, while malignant tumors invade and spread.

What is a mutation?

A change in DNA.

What is a de novo mutation?

A new mutation caused by an error during DNA replication.

What does de novo mean?

New.

What is DNA replication?

The copying of DNA before a cell divides.

What does DNA proofreading do?

It corrects most DNA replication errors.

What mutation rate remains after proofreading according to the packet?

About 1 mutation per 10 million base pairs.

Why are frequently dividing cells at higher risk for mutations?

They copy their DNA more often.

What is a mutagen?

An agent that causes DNA mutations.

What are examples of mutagens in this section?

UV radiation and chemicals.

What is tumorigenesis?

The formation and development of a tumor.

How does tumorigenesis often begin?

A cell becomes dysfunctional because cell-regulation genes are mutated.

What are cell-cycle regulators?

Genes or proteins that control when cells divide, stop, repair DNA, or die.

What can happen when cell-cycle regulators are mutated?

Cells may divide uncontrollably.

What is uncontrolled proliferation?

Cells continuing to divide when they should stop.

Does cancer usually result from only one mutation?

No.

What does mutation accumulation mean?

Additional mutations build up over time.

How can additional mutations affect a tumor?

They can make it more aggressive.

What does aggressive mean in cancer?

Growing faster, invading more, evading immunity, or resisting treatment.

What drives tumor progression according to the packet?

Natural selection.

How does natural selection occur within a tumor?

Cells with traits that improve survival and growth become more common.

Which tumor cells are favored by natural selection?

Cells that divide rapidly, evade immunity, and survive low oxygen.

What is an anaerobic environment?

An environment with little or no oxygen.

Why might a tumor contain anaerobic areas?

It may grow faster than its blood supply can provide oxygen.

What is a tumor antigen?

An abnormal protein on a tumor cell that immune cells may recognize.

What is immune evasion?

A cancer cell avoiding destruction by the immune system.

How may tumor cells evade the immune system?

By changing their protein expression.

What is the basement membrane?

A thin supporting layer that separates and anchors tissues.

Why must malignant cells break through the basement membrane?

To invade nearby tissue and spread.

What is a protease?

An enzyme that breaks down proteins.

How do proteases help cancer spread?

They digest the extracellular matrix.

What is the extracellular matrix?

Supportive material surrounding cells.

What is a growth factor?

A signaling molecule that stimulates cell growth or division.

How can cancer cells use growth factors?

They can secrete them to stimulate their own growth.

What is angiogenesis?

The formation of new blood vessels.

Why do tumors stimulate angiogenesis?

To receive oxygen and nutrients.

What does VEGF stand for?

Vascular endothelial growth factor.

What does VEGF do?

It promotes new blood-vessel growth.

What does the tumor gain from new blood vessels?

Oxygen and nutrients.

What is chemotherapy?

Treatment using chemical agents to kill or slow cancer cells.

What type of cells does chemotherapy mainly target?

Rapidly dividing cells.

Why does chemotherapy cause side effects?

It also damages healthy rapidly dividing cells.

Which healthy cells may be affected by chemotherapy?

Hair, digestive-tract, and blood-forming cells.

What is chemoresistance?

When cancer cells become resistant or less responsive to chemotherapy.

How can chemoresistance develop?

Resistant cells survive treatment and continue dividing.

What is targeted therapy?

Treatment aimed at specific features or molecules of cancer cells.

What is personalized medicine?

Treatment chosen based on the patient or tumor.

What is immunotherapy?

Treatment that helps the immune system recognize and destroy cancer cells.

What are the three newer cancer-treatment approaches listed in the packet?

Targeted therapy, personalized medicine, and immunotherapy.

What is the sequence of metastasis shown in the page 1 diagram?

Tumor growth, basement-membrane invasion, cell detachment, and spread.

What is the sequence of angiogenesis shown in the page 2 diagram?

Tumor releases VEGF, blood vessels grow, and the tumor gains nutrients and oxygen.

What are the major steps in cancer progression?

Mutation, uncontrolled proliferation, additional mutations, invasion, and spread.

What should you remember about benign tumors?

They are localized and contained.

What should you remember about malignant tumors?

They invade and can metastasize.

What should you remember about proteases?

They digest extracellular-matrix proteins and help cancer spread.

What should you remember about angiogenesis?

It supplies tumors with oxygen and nutrients.

What should you remember about chemotherapy?

It targets rapidly dividing cells but can harm healthy ones too.