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Canada (161,663)
Shauna Burke (125)
Chapter 8

Chapter 8: Cancer

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Health Sciences
Health Sciences 1001A/B
Shauna Burke

Chapter 8: Cancer 1 • Cancer: abnormal, uncontrolled multiplication of cells that, if left untreated, can ultimately cause death leading cause of death (Canada), 1/4 • • lifestyle choices: dietary & exercise habits Tumours: • tumour: mass of tissue, serves no psychological purpose • benign (noncancerous)- cells similar to surrounding normal cells, enclosed in membrane that prevents them from penetrating neighboring tissues; only dangerous if interferes w/ functions - ex. blocks blood supply to brain • malignant (cancerous)- invades surrounding structures inc. blood vessels, lymphatic system, nerves • mass=1 billion cells; often take years before grows to noticeable size • ex. breast=lump; leukemia=no lump - > increased fatigue, infection, abnormal bleeding • diagnosis: x-ray, biopsy, indirect symptoms Metastasis: • metastasis: spread of cancer cells from one part of body to another - primary tumour: cancer’s original location • tumour can recruit normal cells, modify them, prepare other sites to receive travelling cancer cells; envoy cells- create proteins that attract free-floating cancer cells, gather at new site, resume replicating (metastasizing), tumours (secondary, metastases) • early stages=not in lymphatic system; cure=not affected lymph nodes Stages of Cancer: • method of classifying progress/extent of cancer in person • Figure 8.2- Tumour stages Types of Cancer: Chapter 8: Cancer 2 • carcinomas: arise from epithelia- tissues that cover external body surfaces, line internal tubes/cavities, form secreting portion of glands; major: skin, uterus, prostate, lungs, gastrointestinal • sarcomas: arise from connective & fibrous tissues; ex. muscle, bone, cartilage • leukemias: blood forming cells, reside chiefly in bone marrow • lymphomas: lymph nodes • oncologist & hematologist: medical specialist in study of blood disorders, inc. cancers The Incidence of Cancer: • 2008: 12 million new cases diagnosed, 7 million deaths, 25 million people living w/ diagnosis • reduction/prevention: 90% less w/ sunscreen (skin), 87% reduce/avoid tobacco smoke (lung) Lung Cancer: Risk Factors: • 30%=all cancer; 85% caused by tobacco smoke; combined w/ other pollutants=10x risk • environmental tobacco smoke (ETS): nonsmoker increase by 20% to people not exposed Detection & Treatment: • tumour presence: persistent cough, chest pain, recurring bronchitis • CT & x-rays=early detection • arise in cells in sputum- line bronchi - > fibre-optic bronchoscopy (flexible rube inserted into windpipe & lung passage surfaces are inspected) addition to surgery=chemotherapy + phototherapy, gene therapy, immunotherapy (vaccine) • • large % go into - > remission: period during course of cancer in which there are no symptoms or other evidence of disease Colon & Rectal Cancer: Risk Factors: • polyp: small, usually harmless, mass of tissue that projects from inner surface of mucous membrane - > determined by specific genes • smoking, excessive alcohol, obesity Chapter 8: Cancer 3 • oral contraceptives/hormone replacement therapy may reduce risk in women • non-steroidal anti-inflammatory drugs (Aspirin)- may reduce risk • protective role: folic acid, refined carbs, vitamin D, calcium • high intake increased risk: carbs, simple sugars, smoked meats/fish Detection & Treatment: • polyps may bleed as they progress - > change in bowel movements • regular screening tests=recommended age 50, yearly blood stool test • sigmoidoscopy, colonoscopy: flexible, fibre-optic device inserted into rectum, can remove polyps w/o surgery Breast Cancer: • 1/9 develop, 1/28 die • 75% over age 50 Risk Factors: • 15% w/ family history (not huge genetic component) • early onset of menstruation, late onset of menopause, having no children/age age 30, use of hormone replacement therapy (HT), obesity, alcohol use • estrogen=circulates in body in high conc. b/w puberty & menopause; increases growth of cells in responsive sites • reduce risk: eat low-fat, vegetable rich diet, exercising, limiting alcohol use, long term use of aspirin & other non-steroidal anti-inflammatory drugs Early Detection: mammogram: low-dose X-ray of breasts (85% detection early stages); over 50+ recommended; • MRI=women w/ dense breast tissue - digital mammograms: exposure to radiation, but benefits outweigh costs - ultrasound: images of soft tissue clinical breast exam: 40-49=every 2 years • • breast awareness: breast self-exam- can increase # of benign breast biopsies conducted; age 20+ recommended - benign conditions: menstruation Chapter 8: Cancer 4 - cancer: lump, swelling/thickening, skin irritation/dimpling, nipple pain, scaliness, retraction Treatment: • ultrasonography: imaging method in which sound waves are bounced off body structures to create image on TV monitor (ultrasound)- > if see lumps • 90% found to be cyst/harmless growth & can be removed - lumpectomy: removal of lump & surrounding tissue - mastectomy: removal of breast • caught before spread to adjacent lymph nodes= 98% survival (5+ years) New Strategies for Treatment & Prevention: • selective estrogen-receptor modulators (SERMs): act like estrogen in some tissues, but blocks effects in other parts of body - tamoxifen- potential side effects: increased risk of blood clots & uterine cancer - raloxifene: osteoporosis drug, less side effects than tamoxifen - advanced cancer: antibodies: produced by immune system, recognize/bind to foreign substances Prostate Cancer: • prostate gland- base of bladder, completely surrounds urethra; produces seminal fluid; if enlarged can block flow of urine • most common in men, 3rd leading death cause Risk Factors: • age: 80% 65+ • inherited: 5-10% • high cal diets, dairy products, animal fats, low in plant foods; obesity, inactivity, history of STIs type 2 diabetes & insulin resistance associated • Detection: • warning signs: changes in urinary frequency, weak/interrupted urine flow, painful urination, blood in urine Chapter 8: Cancer 5 • digital rectal examination & prostate-specific antigen (PSA) blood test: measures level of prostate-specific antigen (PSA); physician feels prostate gland through rectum to determine if gland is enlarged/bumps - new approach: measure percentage of PSAthat is free floating in blood • low proportion of unbound/free PSAindicates greater risk, high proportion=lower risk • older men=many not deadly, making treatments pointless/potentially harmful • ultrasound: lumps too small to be felt/determine size, shape, properties • needle biopsy: if biopsied cells are malignant or benign Treatment: • older men who undergo treatment live longer • aggressive: younger men w/ more advanced cancers • radical prostatectomy: prostate removed surgically; excellent cure rate but often results in incontinence (inability to control flow of urine) or erectile dysfunction • surgical implantation of radioactive seeds: destroys tumour & much of normal prostate tissue, leaves surrounding tissues nearly untouched • external radiation, hormones that shrink tumours, cyrotherapy, chemotherapy • 5 year survival rate: 95% Cancers of the Female Reproductive Tract Cervical Cancer: • women ages 20-30 • stem from STIs: infection by HPV - > common warts + genital warts; at least 75% will develop HPV infection sometime in lifetime • associated w/ multiple sex partners • reduce risk: condoms, circumcised • factors: smoking, genital herpes • HPV 16: high risk for HPV infection to develop into cancer • pap test: scraping of cells from cervix for examination under microscope to detect cancer; recommended: sexually active women, ages 18-65; 40 million - > 8% abnormal Chapter 8: Cancer 6 - cervical dysplasia: cells=abnormal, not yet cancerous; 1/3 develop into cancer - removal: surgically, destroy by cyroscopic (ultra-cold) probe, localized laser treatment - without timely surgery, malignant patch invade cervix walls - even if cured, uterus may have to be removed - Gardasil: protects against 4 types of HPV viruses, 70% of cervical cancer cases; can also protect against cancer of vagina & vulva; women/men: before sexually active, or ages 9-26 Uterine/Endometrial Cancer: • cancer of lining of uterus, endometrium, age 55+ • risk factors: prolonged exposure to estrogen, early onset menstruation, late menopause, never pregnant, obesity, type 2 diabetes, oral contraceptives • pelvic examination: treated surgically, hysterectomy, removal of uterus, radiation treatment, hormones, chemotherapy • 85% caner free 5+ years later Ovarian Cancer: • more deaths than cervical & uterine cancer combined • usually no warning signs • early cues: abnormal size/bloating, urinary urgency, pelvic pain • cannot be detected by pap tests risk factors: increasing age (60+), never having been pregnant, family history of breast/ovarian • cancer, obesity, specific genetic mutations • high chance of cancer-causing genetic mutation- lower ovulation cycles (pregnancy, breastfeeding, oral contraceptives) • diet rich in veggies/fruit • pelvic exams: ultrasound; removal of both ovaries, fallopian tubes, uterus, radiation, chemotherapy; 40% 5 years survival rate Skin Cancer: • most common cancer, highly curable forms Chapter 8: Cancer 7 • melanoma: malignant tumour of skin that arises from pigmented cells, usually a mole Risk Factors: • exposure to ultraviolet (UV) radiation: light rays of specific wavelength emitted by sun; most UV rays are blocked by ozone layer in upper atmosphere;A & B (shorter) • UVB: sunburns, damage to eyes & immune system • UVA: damage connective tissue; premature aging of skin, wrinkled, leathery appearance • sun lamps & tanning beds=carcinogens • people w/ lighter skin=less protection than people w/ darker skin • men more likely to develop & die from melanoma • severe sunburns during childhood=increased chance of skin cancer in future • having many moles (large),
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