CELL DIVISION GOING WRONG: Cancer When cells grow and divide out of control, they cause a group of diseases called cancer.cancer The result is a change.

CELL DIVISION GOING WRONG:Cancer

• When cells grow and divide out of control, they cause a group of diseases called cancer.

• The result is a change in the DNA thatcontrols the cell cycle. This changeprevents the cell from staying ininterphase for the normal periodof time.

• When the normal checkpoints fail,the cell and its daughter cells willdivide uncontrollably.

2.7

cancer

broad group of diseases associated with uncontrolled, unregulated growth of cells cancer begins when the signaling pathways of the cell cycle clock controls

fail cells

communicate information about the body’s needs from one cell to another (i.e a callus forms as accelerated cell division not only replaces damaged cells, but also increases the cell numbers of the epidermis to shield the nerve and blood vessels in the inner layers)

CELL DIVISION GOING WRONG:Cancer

TUMOURS

• Uncontrolled growth may create a

rapidly growing mass of cells that

form a lump, or tumour.

• Tumours may be benign or

malignant. Cells in a malignant

tumour are considered cancerous.

• Cancer cells may break away from

the original tumour and move to a

different part of the body. If they

settle and grow in this new location,

a new tumour will form. This process

of breaking away and creating

secondary tumours is called

metastasis.

2.7

cancer cells can divide in isolation at a very rapid rate, without directions from adjacent cells, (although some cancers grow more slowly as their reproductive rate is regulated somewhat by adjacent cell signals)

isolation of cancer cells from each other and normal cells (they don’t stick) allows them to become dislodged from a tumour and metastasize (move to another area) making it difficult to locate and control

a large health risk factor arises because cancer cells do not specialize into one of the 100 different types of cells, so they replace normal cells that carry out specific functions (i.e. leukemia replaces normal WBC, reducing ability to fight pathogens)

CELL DIVISION GOING WRONG:Cancer

MUTATIONS

• When cells divide, their DNA is

almost always duplicated

error-free. The genetic information

in their daughter cells

is identical to the parent cell.

• Sometimes random changes occur

in the cell’s DNA. These

changes are called mutations.

Changes may result in the death of

the cell or allow it to survive and

continue to grow and divide. If the

cell cycle is abnormal, the cells

may be cancerous.

2.7

mutations

carcinogens

CELL DIVISION GOING WRONG:Cancer

CARCINOGENS

• Some mutations are caused by carcinogens. Carcinogens

are environmental factors that cause cancer. Examples

include tobacco smoke, radiation, some viruses, certain

chemicals, and many organic solvents.

• Lung cancer is the most common type of cancer in

Canadians over 40 years of age. Health Canada reports that

9 out of 10 lung cancer cases are caused by smoking. The

figure at the right identifies other parts of the body that are

affected by the carcinogens in tobacco smoke.

• Some cancers are at least partly hereditary. These include

some breast cancers and colon cancers.

2.7

mutations

carcinogens

Super foods such as these help yourbody protect itself from cancers

CANCER SCREENING

• Factors affecting a person’s risk of getting cancer include– personal and family medical history– exposure to carcinogens in the environment– lifestyle choices, such as eating more

“super foods”

• Cancer screening means checking for cancer

even when no symptoms are present. Screening

can be performed– at home, as part of a routine self-examination– by a doctor, such as a Pap test or blood test– as genetic testing, when there is a family

history of cancer

• While screening does not prevent cancer,

it does increase the likelihood of early

detection and successful treatment.

CELL DIVISION GOING WRONG:Cancer

2.7

pap test

CELL DIVISION GOING WRONG:Cancer

2.7

Vocabulary

Pap test

CANCER DIAGNOSIS AND TREATMENT

• The earlier a cancer is diagnosed, the better the chances of successful treatment. Some

diagnostic imaging techniques include endoscopy, X-ray, ultrasound, CT scanning, and MRI.

• Once an abnormality has been identified, a sample of the cells is removed and examined under

a microscope. This is called a biopsy. This is the only way to positively confirm a diagnosis of

cancer.

• The purpose of cancer treatment is to slow down the growth of tumours or destroy as many

cancer cells as possible. Currently, there are three methods of conventional treatment:– surgery– chemotherapy– radiation therapy

• One new technique to fight cancer is

biophotonics, which uses beams of light

to detect and treat the cancer cells.