Unit # 6: Cancer. Overview 2 nd leading cause of death in Canada 29% of all mortality (2004) Higher risk in people over 65, males Leading cause of Potential.

Unit # 6: Cancer

Overview

• 2nd leading cause of death in Canada• 29% of all mortality (2004)• 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

New cases (A) and Deaths (B) by cancer type in Males

A

B

New cases (A) and Deaths (B) by cancer type in Females

A

B

Incidence (A) and Mortality (B) rates by age

A

B

Incidence (bars) and Mortality rates (line) for males (A) and females (B)

A

B

Worldwide Trends

• Accounted for 7.4 million worldwide deaths (2004)

• Expected to rise to 12 million by 2030• Leading mortal cancers by gender:

– Men: lung, stomach, liver, oesophageal, prostate– Women: breast, lung, stomach, colorectal,

cervical

Mechanism of cancer: How does it happen?

• 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 and spread

Mechanism of cancerThe mutations that result in cancer are caused by:Carcinogens: cancer causing agent

Physical carcinogens: UV light, radiationChemical Carcinogens: asbestos, chemical in tobacco smoke, arsenicBiological carcinogens: viruses, bacteria, parasites

Development of Cancer: “Multiple hits” finally lead to a

genetic change

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

• Summary: oncogenes are cancer _______________ genes and they are turned ______

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• Summary: TSG’s are cancer _____________ genes,

they are turned ____

Neoplasms• Neoplasms are new growths in the body. They occur constantly.

These growths can form a dense group of cells called a _____________________. Not all tumours are cancerous!

• Benign tumours are growths which are enclosed in a membrane.• Still have control over growth• Do not invade• Do not metastasize (spread)• NOT CANCER!!!

• Malignant tumours are cancerous growths which are not enclosed in a membrane• No control over cellular growth• Invade• Metastasize• CANCER!!!

Metastatic tumours (Cancer)

Benign vs. Malignant tumour

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

Cancer Stagingex. Prostate 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)

Cancer Treatment• Cancer treatment is tailored to the individual. Each

case is different.• A team of doctors will consider the: type, stage, age,

general health, medical problems of the patient• Will decide on the best course of action for that

specific patient• Health Care spending for cancer treatment is a huge

burden on both the health care system and the patient/their supporters

MAJOR TYPES OF CANCER

Male incidence rates for different cancers

Male mortality rates for different cancers

Female incidence rates for different cancers

Female mortality rates for different 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• Asbestos• Arsenic• Exposure to Radon Gas• Family history• Previous case of lung cancer• Air pollution

Smoking and Lung Cancer

Lung Cancer

• Symptoms: chronic cough that worsens, breathing problems, chronic chest pain, hoarse voice

• 5-year survival rate: 13% (males); 17% (females)• Screening: No effective screening exists!

Breast Cancer

Female Age-standardized incidence rates for breast cancer

Female Age-standardized mortality rates for breast cancer

What does this suggest??????

Breast cancer risk factors • Females are at much higher risk

• Males = less than 1% • Previous breast cancer• Family history• Family history of ovarian cancer• Above average estrogen exposure (promotes cancerous

growth!)• Early menstruation and late menopause• Never given birth, first child after 60

• Older Age• Also: obesity, alcohol, birth control pills may slightly

increase your risk

Breast Cancer

• Signs and symptoms: lump, changes in breast size/shape, dimpling, puckering of skin, redness, inverted nipple

• 5-year survival rate: 84% (women); 87% (men)

• Screening: multi-stage screening; highly effective!

Breast Cancer Screening

• 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

Multi-level screening

Prostate Cancer

Prostate cancer risk factors

• Age• Family history• African ancestry• Also: obesity, physical inactivity, high fat diet,

very excessive calcium intake may slightly increase risk (all are currently being studied more)

Prostate cancer• Signs and symptoms: frequent/urgent

urination, difficulty with the control of urine flow, inability to urinate, burning/pain urinating, painful ejaculation.– Often NO symptoms are evident! Extremely

important to SCREEN!!! Do not ignore any of the above symptoms!

• 5-year survival rate: 95% with early detection• Screening: PSA test, digital rectal exam

Colorectal Cancer

Colorectal cancer risk factors• Age (50+)• Appearance of polyps (small growth on inner wall

of colon/rectum)• Family history• Inflammatory bowel diseases• Diet high in red meat, processed meat, alcohol• Smoking• Physical inactivity• Obesity• Diet low in vegetables and fruits, fibre

Colorectal Cancer

• Signs and symptoms: change in bowel movements, blood in stool, diarrhea, constipation, narrow stools, abdominal pain, unexplained weight loss

• 5-year survival rate: 61% (males), 62% (women)• Screening: People over 50 are recommended to

have a fecal occult blood test (FOBT) every 2 years minimum

Cervical Cancer

Cervical cancer risk factors

• Infrequent Pap tests• Sexual activity (young, frequent, multiple

partners)• Smoking• Weakened immune system• Long term use of birth control pills• Having many children

Cervical Cancer

• Signs/symptoms: abnormal vaginal bleeding, bleeding between cycles, longer menstruation, increased vaginal discharge, pain in pelvis/during intercourse

• Early detection: Pap test! Get it!

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 (melanoma)

• UV exposure (sunlight/tanning beds)• Unusual moles• Large amount of moles• Light skin, eyes, hair• Skin that burns/freckles easily• History of melanoma• Family history• Severe sunburn during childhood

Skin cancer• Signs/symptoms: new/unusual looking skin

growths, itchy moles, ABCD moles (see figure, next slide)

• 5-year survival rate: depends on the type of skin cancer/ when it is discovered. If skin cancer is discovered and treated before it spreads, survival rate close to 100%!

• Early detection: look for the signs/symptoms of skin cancer, namely the change in appearance of moles

How to Spot Skin Cancer:A B C D

Blood Cancers• Not strongly correlated with increased age,

affects young and old• There are many types of cancers that affect

the blood. They are named for the type of blood tissue they affect:– Leukemia: affects leukocytes (white blood cells)– Lymphoma: affects lymphocytes (ie. B/T cells)– Myeloma: affects plasma cells (recall, become B

cells)

Blood Cancers• Cause is unknown!!! • Signs/symptoms: not always obvious! May notice

chronic fever, unexplained weight loss, tiredness, shortness of breath, bruising, bleeding, difficulty healing

• 5-year survival rate: varies greatly depending on age/ when detected!– 23.4%(adults with acute myelogenous leukemia) – 90.9%

(children under 5 with acute lymphocytic leukemia)

• Early detection: no effective screening, watch for signs/symptoms

Primary Prevention of CancerAvoid the major risk factors!

• Tobacco use• Overweight/obesity • low fruit and vegetable intake• Physical inactivity• Alcohol use• Chronic HPV infection• Urban air pollution

5 gives you 50%

• The BC Cancer agency stresses that changing just 5 main lifestyle behaviours reduces your risk of cancer by approximately 50%!!!– Smoking– Physical inactivity– Poor diet (fats, low fibre, high salt, high protein)– Sunlight exposure– Unhealthy weight