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 Tumor Tumor = 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 Benign Malignant

How do cells METASTASIZE? METASTASIS = a cell arising from an original tumor migrates to another site. 1. Cell must break tumor capsule 2. Must infiltrate the bloodstream 3. Must survive hostile environment 4. Must stop within blood vessels 5. Must exit vessel and invade another organ 6. 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-oncogenes genes that accelerate cell growth - GOOD Tumor Supressors genes that normally stop cell division - GOOD mutation would lead to under expression of these genes - uncontrolled growth - BAD Mutation Oncogenes Leads to over expression of these genes – uncontrolled growth - BAD

Examples of genes gone awry ras ras 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) p53 p53 A tumor suppressor gene Normally stimulates apoptosis – programmed cell death Mutated in 50% of all human cancers

ras 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

p53 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