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Cancer: A Comprehensive Overview of Types, Risk Factors, Detection, and Treatment, Study notes of Physical Activity and Sport Sciences

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Chapter 12: Cancer
What is Cancer
Cancer is the abnormal, uncontrolled growth of cells, which left
untreated, can ultimately cause death.
Most cancers take the form of tumours, although not al tumours
are cancerous.
A tumour is simply a mass of tissue that serves no physiological
purpose. It can be benign, like a wart or malignant, like most
lung cancers.
Benign Tumours are made up of cells similar to the surrounding
normal cells and are enclosed in a membrane that prevents them
from penetrating neighbouring tissues. They are dangerous only
if their physical presence interferes with body functions.
Malignant tumour (neoplasm) is synonymous with cancer. A
malignant tumour/ cancer is capable of invading surrounding
structures, including blood vessels, the lymphatic system and
nerves. It can also spread to distant sites via blood and lymphatic
system. Cancers like leukemia (cancer of the blood) do not
produce a mass but still have the fundamental property of rapid,
uncontrolled growth of cells.
A tumour that is cancerous and capable of spreading.
Every case of cancer begins as a change in a cell that allows it to
grow and divide when it should not.
A malignant cell divides without regard for normal control
mechanism and gradually produces a mass of abnormal cells, or
a tumour.
It takes about a million cells to make a mass the size of a pea, so
a single tumour cell must go through many divisions, often
taking years before the tumours grows to a noticeable size.
Eventually a tumour produces a sign or symptom that is
detected. In an accessible location, a tumour may be felt as a
lump. In less accessible location a tumour may be noticed only
after considerable growth has taken place and may then be
detected only by an indirect symptom – for instance a persistent
cough or unexplained bleeding or pain.
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Chapter 12: Cancer

What is Cancer

  • Cancer is the abnormal, uncontrolled growth of cells, which left untreated, can ultimately cause death.
  • Most cancers take the form of tumours, although not al tumours are cancerous.
  • A tumour is simply a mass of tissue that serves no physiological purpose. It can be benign, like a wart or malignant, like most lung cancers.
  • Benign Tumours are made up of cells similar to the surrounding normal cells and are enclosed in a membrane that prevents them from penetrating neighbouring tissues. They are dangerous only if their physical presence interferes with body functions.
  • Malignant tumour (neoplasm) is synonymous with cancer. A malignant tumour/ cancer is capable of invading surrounding structures, including blood vessels, the lymphatic system and nerves. It can also spread to distant sites via blood and lymphatic system. Cancers like leukemia (cancer of the blood) do not produce a mass but still have the fundamental property of rapid, uncontrolled growth of cells. - A tumour that is cancerous and capable of spreading.
  • Every case of cancer begins as a change in a cell that allows it to grow and divide when it should not.
  • A malignant cell divides without regard for normal control mechanism and gradually produces a mass of abnormal cells, or a tumour.
  • It takes about a million cells to make a mass the size of a pea, so a single tumour cell must go through many divisions, often taking years before the tumours grows to a noticeable size.
  • Eventually a tumour produces a sign or symptom that is detected. In an accessible location, a tumour may be felt as a lump. In less accessible location a tumour may be noticed only after considerable growth has taken place and may then be detected only by an indirect symptom – for instance a persistent cough or unexplained bleeding or pain.
  • Metastasis: is the spreading to cancer cells from one part o the body to another, which occurs because cancer cells do not stick to each other as strongly as normal cells do and therefore may not remain at the site the primary tumour. - They break away and can pass through the lining of lymph or blood vessels to invade nearby tissue. - They can also drift to distant parts of the body, where they establish new colonies of cancers cells. This travelling and seeding process is called metastasizing, and the new tumours are called secondary tumours, or metastases. - The ability of cancer cells to metastasize makes early cancer detection critical. To control cancer and prevent death, every cancerous cell must be removed. Once cancer cells enter either the lymphatic system or the bloodstream, its is extremely difficult to stop their spread.
  • Lymphatic system: a system of vessels that returns protein, lipids, and other substances from fluids on the tissues to the circulatory system
  • Carcinogen: any substance that causes cancer

Lung Cancer

  • Is the most common cause of death in Canada.
  • It its responsible for about 17 642 deaths each year
  • Chief risk factor is tobacco smoke, which accounts for 30% of all cancers.
  • When smoking is combined with exposure to other environmental carcinogens, such as asbestos particles, the risk of cancer can be multiplied by 10x or more.
  • Long term exposure to ETS or second hand smoke, also increase risk for lung cancer.
  • The risk of lung cancer is 20% greater for non-smokers exposed to second hand smoke than for people who are unexposed.
  • Symptoms of lung cancer do not usually appear until the disease has advanced to the invasive stage.
  • Signals such as a persistent cough, chest pain, or recurring bronchitis may be the first indication of a tumours presence.
  • Is most often treated by some combination of surgery, radiation, and chemotherapy.
  • If all the tumour cells can be removed than a cure possible.

Brest Cancer

  • Most common cancer in women and is second to lung cancer is number of death in women.
  • Breast cancer in mean occurs rarely
  • 1 in 9 women will develop breast cancer in her lifetime
  • Risk factors:
    • Genetic factors
    • Women who have 2 close relatives with breast cancer is 4-6x more likely to develop breast cancer. Only about 15% of cancers occur in women with a family history.
    • Early onset of menstruation
    • Late onset of menopause
    • Having no children or having a first child after the age of 30
    • Current use of hormone replace therapy
    • Being obese
    • Using alcohol
    • Heredity
    • Inactivity
    • Diet low in vegetable and fibre

The female hormone estrogen may be a common element in some risk factors

  • Estrogen promotes cell growth in responsive tissues, such as breast and uterus, so any factor that increase estrogen exposure may raise the risk of breast cancer.
  • Fat cells also produce estrogen, and estrogen levels are high in obese women.
  • Alcohol can increase estrogen in the blood

Prevention

  • Lifestyle modification may reduce the risk
  • Exercise – helps control body weight and may reduce estrogen levels.
  • Diet – eating plenty of vegetables and monounsaturated fat over polyunsaturated fate.

Detection and Diagnosis

  • Early detection is promoted through a 3 part approach .1 Mammography - A mammogram is a low-dose breast x ray which can spot breast abnormalities before physical symptoms arise. A digital mammography may provide more accurate results in some women, as well as an MRI.

Experts recommend women over 40 get a mammogram done annually. .2 Clinical Breast Exams

  • Women between ages 20 and 39 should have a clinically breast exam every 3 years. Women over 40 should have one every year. .3 Be breast Aware : become more breast aware by
  • Knowing how your breast normally look and feel
  • Knowing what changes to look for
  • Looking for feelings and changes
  • Reporting any change to your physician
  • Following mammogram guideline by participating in your regional breast screening program.

If a lump is detected, it can be biopised or scanned by ultrasonography to determine whether its is cancerous. In 90% of cases, the lump is found to be harmless

Treatment (if lump is cancerous)

  • Lumpectomy – removal of lump and surrounding tissue
  • Mastectomy – removal of breast
  • Chemotherapy / radiation may also be used to eradicate as many cancerous cells as possible.
  • New drugs development for prevention and treatment
    • Selective estrogen-receptor modulators (SERM): which act like estrogen in some tissue but block estrogens effect in others. Best known SERM :tamoxifen and raloxifene
    • Trastuzumab (herceptin): is a special type of antibody that binds to a specific cancer-related target in the body

Biopsy: the removal and examination of a small piece of body tissue for the purpose of diagnosis.

Ultrasonography: an imaging method in which inaudible high- pitched sound (ultrasound) is bounced off body structures to create an image on a monitor.

Prostate Cancer

  • Most common cancer in men and second to lung cancer in number of death among men.
  • The prostate gland is situated at the base of the bladder in men.