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Unit # 6: Cancer. Overview. 2 nd leading cause of death in Canada. 29% of all mortality in 2000 Higher risk in people over 65, males Leading cause of Potential Years of Life Lost (PYLL) Ex. PYLL A man who has a life expectancy of 70 dies at age 65 from cancer, his PYLL = 70-65 = 5.
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Overview • 2nd leading cause of death in Canada. • 29% of all mortality in 2000 • Higher risk in people over 65, males • Leading cause of Potential Years of Life Lost (PYLL) • Ex. PYLL • A man who has a life expectancy of 70 dies at age 65 from cancer, his PYLL = 70-65 = 5
Deaths and ASMR for all cancers ASMR= age standardized mortality rate
Mechanism of cancer • Normal, healthy cells have genes which control: • When they divide • When they stop dividing • When they die • Repetitive exposure to certain agents can cause an accumulation of mutations in these genes, and they lose this control • Cancer is a disease evidenced by: uncontrolled cell growth
Mechanism of cancer The mutations that result in cancer are caused by: Carcinogens: cancer causing agent • Tobacco Smoke • Radiation: UV, X-Ray • Pathogens: Human Pappiloma Virus, Hepatitis B • Benzene • Asbestos
Main Genes Responsible for Cancer • Proto-oncogens/oncogenes • Proto-oncogenes regulate • how often a cell divides • how specialized it is (able to perform a particular task) • A mutation turns proto-oncogenes into oncogenes and the cell no longer has regulated control over division
Main Genes Responsible for Cancer • Tumour Suppressor Genes • normally function to suppress cancerous growth by: • Suppressing uncontrolled growth • Repairing DNA mutations • Telling the cell when to die • Mutations can turn these genes off
Tumour characteristics • Benign tumours are growths which are enclosed in a membrane • Still have control over growth • Do not invade • Do not metastasize (spread) • Malignant tumours are cancerous growths which are not enclosed in a membrane • No control over cellular growth • Invade • metastasize
Cancer Staging • Overall Stage Grouping • Stage 0: a growth that stays in place, no metastasis, no invasion • Stage 1: cancer localized to one area • Stage 2: cancer is localized to one area, but is more aggressive • Stage 3: invasion into local areas and/or lymph nodes • Stage 4: Metastatic cancer
Survival Rate • Cancer is considered cured if patient lives five years after original diagnosis • Varies with the type of cancer. • Ex. High with skin cancer, low with brain cancer • Survival rate increases with EARLY DETECTION! • However, cancer can have a very long latent period • latent period = time between first exposure to a carcinogen (ex. Cigarette smoke) and the first signs and symptoms showing (ex. Lung cancer)
Cancer Treatment in General • Surgery • Radiation • Chemotherapy (drugs)
Female Age-standardized mortality rates for selected cancers
Lung Cancer • Highest mortality rate of any cancer • Rates are actually increasing in Canadian females
Lung Cancer Risk Factors • Smoking is the leading risk factor • Smokers are 10-20 times more likely to get lung cancer than non-smoking population • Cigarette tar is the most carcinogenic • Asbestos can also cause lung cancer • Previously used to insulate schools, hospitals, buildings • Risk increases substantially when patient is exposed to both carcinogens • No effective screening for lung cancer in place
Globe and Mail, Sept 29, 2009 “Ontario says tobacco use costs the province $1.6-billion a year for health care and causes about 13,000 deaths annually. It said smoking is the province's No. 1 cause of illness and premature death”
Breast Cancer • 2nd most common cancer worldwide • 5th mortal cancer
Female Age-standardized incidence rates for breast cancer Female Age-standardized mortality rates for breast cancer What does this suggest??????
Risk factors for breast cancer • Females are at much higher risk (obviously!) • Older Age • Family history • Early menstruation and late menopause: since estrogen is known to promote breast tumour growth • Pregnancy: if first pregnancy occurs after age 30 • Diet: dietary fat? Alcohol? • Physical Inactivity
Preventing breast cancer • Mostly secondary prevention measures • Breast self-examination • Mammography a low dose breast X-ray • Multi-stage screening: • Involves an initial general screening test, then subsequent diagnostic tests become more and more specific • Note: screening is done on healthy populations, testing is done on people who already have the disease
Prostate cancer • Risk factors include the male gender, family history and older age • Often no symptoms are evident. However less rigid erections, decreased ejaculated fluid, blood in the urine or semen and severe back, pelvis, hip or thigh pain may be evidenced
Prostate cancer detection • Digital rectal exam: Recommended for all Canadian men over age 50 • Prostate specific antigen (PSA): paid for by the Canadian government for males over 50
Prostate Cancer Treatment • Surgical removal of the gland • Small radioactive material can be implanted to kill cancerous cells • Cryotherapy: freezing the prostate • Drugs: to decrease male hormone levels
Colorectal Cancer • Third leading cause of cancer mortality in Canadian males and females • Higher in populations with poor diets • High meat, high-fat, high-protein, low-fibre, low-calcium • Begins with the appearance of adenomatous polyps (polyps = non-cancerous growths) • These polyps can become cancerous and the disease progresses accordingly
Colorectal Cancer • Symptoms include: • bowel movement change lasting more than 10 days • Pain and tenderness in the abdomen • Blood in the stool • Risk factors include: • Older age • Male gender • Inflammatory bowel disease • Hereditary factors • Family history • Physical Inactivity
Cervical Cancer • Affects only females • Can be detected early with the Pap test • Risk factors include: • early age of sexual intercourse • multiple sex partners • history of STDs • tobacco use
Skin Cancer • Most commonly diagnosed cancer • Easy to treat since it’s on the surface • It rarely metastasizes • Basal cell carcinoma= most common, easier to treat • Malignant melanoma= more aggressive, metastasizes
Skin Cancer Risk Factors • Tobacco Smoke • UV exposure • Chronic non-healing wounds • Genetic predisposition • HPV infection • Age
Prevention of Cancer • Primary prevention aimed at reducing risk factors is useful. However, the cause of cancer is often unknown • Don’t smoke! • Reduce UV exposure • Minimize X-ray exposure • Reduce fat intake
Prevention of Cancer • Increase fibre consumption • Get adequate amounts of beta-carotene (Vitamin A precursor) and Vitamin C • Reduce consumption of smoked, barbecued and salted foods • Keep a healthy weight • Sleep at night; avoid night time shift work • Avoid nitrites • Clean with vinegar, avoid detergents
