Cancer

What is cancer?

How does it form?

How can it be treated?

What is Cancer?

A disease of cells Normal cells that lose the ability to control the rate

at which they grow and divide When good cells go bad = TRANSFORMATION These transformed cells may also spread to other

parts of the body and establish new colonies. “Immortal” cells

How do normal cells behave?

Growth = mitosis Cells begin mitosis in

response growth factors. Cells grow until they run

out of room - called contact inhibition

Cells must be anchored to some type of basement membrane while growing and dividing.

Tumors

TumorTumor = a group of cells that have lost their ability to control the rate at which grow and divide.

Cells have lost contact inhibition, they don’t know to stop dividing.

This abnormal mass can cause damage to surrounding tissues

Types of tumors

single mass of cells contained within a capsule

do not spread can cause abnormal

pressure and can obstruct normal processes

cells from a contained tumor have broken free of the capsule

travel in bloodstream or lymph vessels

spread to other parts of the body

process called METASTASIS

BenignBenign MalignantMalignant

How do cells METASTASIZE?

METASTASIS = a cell arising from an original tumor migrates to another site.

1. Cell must break tumor capsule2. Must infiltrate the bloodstream3. Must survive hostile environment4. Must stop within blood vessels5. Must exit vessel and invade another organ6. Must establish a nutrient supply (angiogenesis)

Metastasis of breast cancer cells

Terminology

Malignant tumors 90% are carcinomas 2% are sarcomas 8% are leukemias

Benign tumors end in -oma

Identification of Malignancies

BIOPSY – taking a sample from a suspicious area and growing the cells in culture. increase in cell number loss of regular arrangement variation in cell shape and size increase in size of nucleus (extra DNA) abnormal mitosis abnormal chromosome numbers high levels of telomerase activity

When “Good” genes go “Bad”

Proto-oncogenesProto-oncogenes genes that accelerate

cell growth - GOOD

Tumor SupressorsTumor Supressors genes that normally stop

cell division - GOOD mutation would lead to

under expression of these genes - uncontrolled growth - BAD

Mutation

OncogenesOncogenes• Leads to over expression of these genes – uncontrolled growth - BAD

Examples of genes gone awry

rasras A proto-oncogene An important protein a

cell signal pathway that regulates the cell cycle

Is mutated in 30% of all human cancers (has become an oncogene)

p53p53 A tumor suppressor

gene Normally stimulates

apoptosis – programmed cell death

Mutated in 50% of all human cancers

rasras A protein (made from a

gene) Part of the cell signalling

pathway that accelerates growth

If gene is mutated, protein issues signals of its own

Activiates cell division too often

p53p53 A protein that

stimulates genes to make proteins that inhibit cell division

Defective p53 does not stimulate the gene to make the protein that will inhibit division.

Immortality of cell

What causes cancer?

Process of carcinogenesis has 2 steps: initiation - the initial insult to a cell (mutation) promotion - 2nd insult that leads to cancer

What can act as initiators or promoters? Chemical carcinogens viruses radiation replication errors hormones / growth factors inherited faulty genes

Cancer is a multistep process

5 most common cancers

5. Prostate Cancer 43% five year survival rate

4. Breast Cancer- 62% five year survival rate

3. Colorectal Cancer- 37% five year survival rate

2. Stomach Cancer- 10% five year survival rate

1. Lung Cancer- 7% five year survival rate

Cancer Treatments

Surgery Radiation Therapy

Internal External

Chemotherapy Hormone Therapy Anti-angiogenic factors

Ways to reduce risk

NO SMOKING low fat diet low salt diet limit amount of high energy radiation reduce amount of chronic inflammation or

infection (cells are constantly regrowing) be aware of occupational hazards