Presentation on theme: "Cancer Some cells, instead of leaving the cell cycle to die, divide repeatedly and excessively, forming a clump of cells called a tumour. Cancer is a disease."— Presentation transcript:
Cancer Some cells, instead of leaving the cell cycle to die, divide repeatedly and excessively, forming a clump of cells called a tumour. Cancer is a disease that eventually disrupts the body functions, whereas a tumour is a mass of cells with no apparent function in the body. Cancer is the uncontrolled division and spread of abnormal cells.
An estimated 171,000 new cases of cancer (excluding 75,100 non- melanoma skin cancers), and 75,300 deaths from cancer are expected to occur in Canada in each year.
About 40 per cent of Canadian women and 45 per cent of men will develop cancer during their lifetimes.
About 24 per cent of women and 29 per cent of men, or approximately one out of four Canadians, is expected to die from cancer.
Benign: (non cancerous) harmless tumours that do not spread Malignant: harmful tumours that have the potential to spread through the body Metastatic: tumours that have travelled and grown in other areas Three Tumour Types
Different Kinds of Cancer Fat Bone Muscle Lymphomas: Leukemias: Some common carcinomas: Lung Breast (women) Colon Prostate (men) Bladder Lymph nodes Bloodstream Some common sarcomas:
Q1: Do you know someone personally that has had cancer? A: Yes B: No
Loss of Normal Growth Control Cancer cell division Fourth or later mutation Third mutation Second mutation First mutation Uncontrolled growth Cell Suicide or Apoptosis Cell damage— no repair Normal cell division
Example of Normal Growth Cell migration Cell migration Dermis Dividing cells in basal layer Dead cells shed from outer surface Epidermis
The Beginning of Cancerous Growth Underlying tissue
Invasion and Metastasis 3 Cancer cells reinvade and grow at new location 3 Cancer cells reinvade and grow at new location 1 Cancer cells invade surrounding tissues and blood vessels 1 Cancer cells invade surrounding tissues and blood vessels 2 Cancer cells are transported by the circulatory system to distant sites 2 Cancer cells are transported by the circulatory system to distant sites
Malignant versus Benign Tumors Time Malignant (cancer) cells invade neighboring tissues, enter blood vessels, and metastasize to different sites Benign (not cancer) tumor cells grow only locally and cannot spread by invasion or metastasis
Cancer Tends to Involve Multiple Mutations Malignant cells invade neighboring tissues, enter blood vessels, and metastasize to different sites More mutations, more genetic instability, metastatic disease Proto-oncogenes mutate to oncogenes Mutations inactivate DNA repair genes Cells proliferate Mutation inactivates suppressor gene Benign tumor cells grow only locally and cannot spread by invasion or metastasis Time
Q2: Why might cancer primarily affect older people rather than young people? A: Because the immune system of older people is not as effective in distinguishing normal cells from cancer cells. B: Because older people have been exposed to more carcinogens. C: Because cancer develops after multiple mutations have occurred which takes years to happen. D: None of the above.
Why Cancer Is Potentially Dangerous Melanoma cells travel through bloodstream Melanoma (initial tumor) Brain Liver
Microscopic Appearance of Cancer Cells
What Causes Cancer? Some viruses or bacteria Heredity Diet Hormones Heredity Diet Hormones Radiation Some chemicals
Cancer arises from the accumulation of genetic changes or mutations. Most cancers have a minimum of 6-9 genes involved. People can be susceptible to cancer based on their genetic makeup, but cancer isn’t directly passed from parent to child. Many genes that are involved in cancer are involved in regulating the cell cycle. Cancer cells generally have multiple mutations before control over cell division is lost. Mutations
Tumour suppressor gene A tumour supressor gene like P53 controls or slows the cell cycle and thus cell division. When it is mutated or absent, the cell will divide uncontrollably. An oncogene is a gene that when mutated will lead to uncontrolled cell division.
Cancer cells divide too quickly and can leave the original site and enter the blood, lymph, or tissues. Most cells divide a set number (60-70) of times, then they stop dividing. This usually limits benign tumors to small sizes. Cancer cells can divide indefinitely. From Benign to Malignant
Radiation - Uses high-energy rays to kill cancer cells. A large machine directs radiation at the body. Chemotherapy - Uses anticancer drugs to kill cancer cells. Surgery - Physically removes cancer cells Many patients will use combinations of these Treatment Options
26 Taxol One common chemotherapy for ovarian cancer is Taxol, which was first isolated from Yew bark in 1962 by the National Cancer Institutes (NCI). Taxol blocks a cell's ability to break down the mitotic spindle during mitosis. With the spindle still in place, the cell can't divide into daughter cells and therefore the cancer can’t grow. Taxus Brevifolia
27 Cancer Detection and Treatment Earlier detection and treatment of cancer greatly increase the odds of survival. Therefore, knowing the warning signs of cancer is important to health. C hange in bowel or bladder habits A sore that does not heal U nusual bleeding or discharge T thickening or lump I ndigestion or difficulty swallowing O bvious change in wart or mole N agging cough or hoarseness
Population-Based Studies CANADA: Leukemia CANADA: Leukemia Regions of Highest Incidence BRAZIL: Cervical cancer BRAZIL: Cervical cancer U.S.: Colon cancer U.S.: Colon cancer AUSTRALIA: Skin cancer AUSTRALIA: Skin cancer CHINA: Liver cancer CHINA: Liver cancer U.K.: Lung cancer U.K.: Lung cancer JAPAN: Stomach cancer JAPAN: Stomach cancer
Heredity? Behaviors? Other Factors? 100 50 5 0 100 50 5 0 Stomach Cancer (Number of new cases per 100,000 people) Stomach Cancer (Number of new cases per 100,000 people) U.S. Japan Japanese families in U.S. 100 70 7 0 100 70 7 0 Colon Cancer (Number of new cases per 100,000 people) U.S. Japan Japanese families in U.S.
Tobacco Use and Cancer Some Cancer-Causing Chemicals in Tobacco Smoke
Lag Time 4000 3000 2000 1000 4000 3000 2000 1000 20-Year Lag Time Between Smoking and Lung Cancer Cigarettes Smoked per Person per Year Cigarettes Smoked per Person per Year Lung Cancer Deaths (per 100,000 people) Year Lung cancer (men) Cigarette consumption (men) 1900 1920 1940 1960 1980 150 100 50 150 100 50
Avoid Tobacco 15x 10x 5x 15x 10x 5x Non-smoker Cigarettes Smoked per Day Lung Cancer Risk Increases with Cigarette Consumption Lung Cancer Risk 0 15 30
Viruses Virus inserts and changes genes for cell growth Cancer-linked virus
Examples of Human Cancer Viruses Some Viruses Associated with Human Cancers
Avoid Cancer Viruses Noninfected women HPV Infection Increases Risk for Cervical Cancer Cervical Cancer Risk Low High Women infected with HPV
Limit Alcohol and Tobacco 40x 30x 20x 10x 40x 30x 20x 10x Alcoholic Drinks Consumed per Day Packs of Cigarettes Consumed per Day Combination of Alcohol and Cigarettes Increases Risk for Cancer of the Esophagus Risk Increase AND
Diet: Limit Fats and Calories 0 0 Number of Cases (per 100,000 people) Grams (per person per day) Correlation Between Meat Consumption and Colon Cancer Rates in Different Countries 40 30 20 10 300 200 100 80
Diet: Consume Fruits and Vegetables
Protect Yourself From Excessive Sunlight
Avoid Carcinogens Some Carcinogens in the Workplace