Cell Division Going Wrong: Cancer PDF

# Cell Division Going Wrong: Cancer ## Cell Growth Rates and Cancer - A cancer cell is one that continues to divide despite messages from the nucleus or the surrounding cells to stop growing and dividing. - The uncontrolled growth and division may create a rapidly growing mass of cells that form a...

# Cell Division Going Wrong: Cancer ## Cell Growth Rates and Cancer - A cancer cell is one that continues to divide despite messages from the nucleus or the surrounding cells to stop growing and dividing. - The uncontrolled growth and division may create a rapidly growing mass of cells that form a lump or tumor. | Normal | Cancer | |---|---| | | Large, variably shaped nuclei | | | Many dividing cells; Disorganized arrangement | | | Variation in size and shape | | | Loss of normal features | ## Normal vs. Cancerous Cells **Normal Cells:** - Many cells that continue to grow and divide - Variations in size and shapes of cells - Nucleus that is larger and darker than normal **Cancerous Cells:** - Many cells that continue to grow and divide - Variations in size and shapes of cells - Nucleus that is larger and darker than normal - Abnormal number of chromosomes arranged in a disorganized fashion - Cluster of cells without a boundary ## Normal Cell vs. Cancer Cell | Normal Cell | Cancer Cell | |---|---| | Make exact copies of themselves through mitosis | Make exact copies of themselves through mitosis | | Reproduce for about 50-60 cell divisions | Do not stop reproducing | | Stick together to from masses of cells as appropriate | Do not stick to other cells; behave independently | | Self-destruct when too old or too damaged | May move to another location of the body | ## Normal vs. Cancer Cell - (a) Normal cell diagram showing how a damaged cell undergoes apoptosis. - (b) Cancer cell diagram showing how a cancer cell divides rapidly. ## Cell Growth Rates and Cancer - **Benign tumor:** Cells of a tumor that stay together and have no serious effect on surrounding tissues, other than physically crowding them; they are not cancerous. - **Malignant tumor:** A mass of cells that interferes with the functions of neighboring cells and tissues; they can interfere with the production of enzymes or hormones, or destroy surrounding tissues; they are cancerous. ## Benign vs. Malignant Tumors | Benign | Malignant | |---|---| | Benign (not cancer) tumor cells grow only locally and cannot spread by invasion or metastasis | Malignant (cancer) cells invade neighboring tissues, enter blood vessels, and metastasize to different sites | ## Cell Growth Rates and Cancer - **Metastasis** occurs when cancer cells break away from the original tumor and move to a different part of the body. - If they settle there and continue to grow and divide uncontrollably, they can start **another tumor** - it is this process that accounts for one of the reasons why cancer is such a dangerous disease. ## Metastasis Diagram Illustrates how cancer cells break away from the original tumor and travel to other parts of the body. - **1:** Normal skin surface - **2:** Tumor growing beneath the skin - **3:** Invasive tumor ## Normal vs. Cancerous Cells - Normal cell - Potentially cancerous cell - Malignant (cancerous) tumor affects surrounding cells - Metastatic (cancerous) cells leave the tumor and start a secondary tumor elsewhere - Benign (non-cancerous tumor does not affect surrounding cells unless by physically crowding them ## Metastasis Diagram Illustrates how cells from an original tumor can break through the blood vessel walls and travel to other areas of the body. - **Tumor:** A tumor with blood vessels - **Cells from original tumor may break through blood vessel walls and travel to other areas of the body** - **Metastatic tumor is established by these migrating cells** ## Causes of Cancer - Every time a cell divides, its DNA is duplicated. - Usually, genetic information in the daughter cells is exactly the same as the parent cell. - However, sometimes random changes in the DNA occur. - These random changes in the DNA are known as mutations. ## Causes of Cancer - Once the crucial DNA starts behaving abnormally, the cells may become cancerous and proliferate wildly through repeated, uncontrolled mitosis and cytokinesis; They multiply until all nutrients are exhausted. - Some mutations are caused by carcinogens (environmental factors that cause cancer) such as tobacco smoke, radiation (x-rays, UV rays from tanning beds and sunlight), some viruses (HPV and hepatitis B), chemicals in plastics, and many organic solvents. ## Causes of Cancer - If a group of people is exposed to a carcinogen, some will develop cancer, some will not - this is a major stumbling block for researchers because they cannot predict who will develop cancer. - Some cancers may be partially hereditary, meaning that DNA passed down to one generation to another may contain information that leads to disease; these include some breast cancers and some colon cancers. - A genetic link makes it more likely that you may develop a particular type of cancer, but it does not guarantee that you will get cancer. ## Smoking and Cancer - Lung cancer is one of the most common types of cancer in Canadians over 40. - Smoking is responsible for 90% of cases of lung cancer. - Carcinogens in smoke affect more than just the lungs. - Most smoking-related cancers can be prevented by giving up smoking, or never starting at all and avoiding second-hand smoke. ## Cancer Screening - Cancer screening means checking for cancer even if there are no symptoms. - It can be done at home or in a doctor's office. - Important for people who have a family history of certain cancers, such as breast cancer or colon cancer. - Genetic screening will determine if you have inherited DNA that is linked to cancer. - Screening does not prevent cancer, but it does increase the chance of detecting cancer early enough to successfully treat it. ## Taking Responsibility For Your Health - Women: Regular breast self-examinations to check for lumps that may indicate breast cancer; regular pap tests to screen for cervical cancer. - Men: Testicular self-examination to detect **testicular cancer**; PSA test to screen for **prostate cancer** (after age of 50). ## Taking Responsibility For Your Health - Blood tests for colon cancer. - Regular skin checks by a doctor or dermatologist; you can check your own skin regularly for moles by using the ABCD of moles: - A: **Asymmetry** - B: **Border** - C: **Colour** - D: **Diameter** ## ABCD of Moles | | Asymmetry | Border | Colour | Diameter | |---|---|---|---|---| | **Benign** | | | | | | **Malignant** | | | | | ## Reducing Your Risk Of Cancer - Prevention and early detection. - Lifestyle choices: - Healthy diet: Lots of fruits and vegetables; less fatty meats; certain "superfoods" (tomatoes, carrots, avocados, grapefruit, red grapes, broccoli, garlic, raspberries, nuts, cabbage, figs) will lower your risk for cancer, but they will not prevent cancer. - Healthy weight and regular exercise. ## Diagnosing Cancer - Symptoms include swelling, discomfort, fatigue, or unaccounted weight loss. - The earlier the diagnosis, the better the chances for successful treatment. ## Imaging Technologies **Endoscopy:** - Used to screen for colon cancer. - A patient is sedated and an endoscope (a fiber-optic cable delivers light, a small camera, and a cable that sends images to the screen) is inserted into the colon through the rectum. ## Imaging Technologies - **X-Ray Images:** View parts of the body, such as bones and lungs; they may, however, cause DNA damage, particularly to rapidly dividing cells such as those in a growing fetus. ## Imaging Technologies - **Ultrasound Imaging:** Uses ultra-high frequency sound waves to create a digital image; useful for viewing soft tissues, such as the heart or liver. ## Imaging Technologies - **CT or CAT (computerized axial tomography) scan:** Allows multiple X-rays from many different angles; enables parts of the body to be viewed that cannot be seen with a conventional X-ray. - **MRI (magnetic resonance imaging):** Radio waves and a strong magnetic field create images that are more detailed than a CT scan. ## Examining Cells - Blood cell samples are obtained and viewed under a microscope, e.g. leukemia will be detected by a high ratio of white to red blood cells. - Tumor cells can be obtained through a biopsy and then viewed under a microscope as well as being tested for genetic abnormalities ## Examining Cells - Cancer cells are often irregularly shaped and may be smaller or larger than surrounding cells. - After diagnosis, doctors must determine the origin and size of the tumor, how quickly it is growing, and whether the cancer has spread; This information will help to determine suitable treatments and predict outcome. ## Treatment For Cancer - **1. Surgery:** - Physically removing the cancerous tissue. - Only done if the tumor is easily accessible and fairly well defined. ## Treatment For Cancer - **2. Chemotherapy:** - Drugs (chemicals) are either injected or taken orally. - These drugs work by slowing or stopping the cancer cells from dividing and spreading to other parts of the body, and by killing the cells. - **Side effects:** - Hair loss - Nausea - Fatigue/tiredness ## Treatment For Cancer - **2. Chemotherapy:** - Benefits generally outweigh the negative effects. - Often one of the first stages of cancer treatment. - Aims to shrink a tumor for surgical removal or for radiation treatment. - **Advantage:** Drugs travel throughout the body and reach almost all tumors, even if they are too small to be detected. ## Treatment For Cancer - **3. Radiation:** - Ionizing radiation is used to damage DNA of many of the daughter cells, preventing them from dividing further. - Radiation is directed at the tumor, serving to minimize side effects. ## Treatment For Cancer - **4. Biophotonics:** - Uses beams of light to detect and treat cancer. - Very sensitive diagnostic tool, allowing for early detection of cancer. - Fewer side effects than conventional radiation, as it can more accurately target the cancerous cell. ## Treatment For Cancer - **5. Genomics:** - Identifies the gene mutations which are driving a patient's cancer, in hopes of developing personalized and more effective treatment. - Shift from organ-focus to gene-focus.