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Cancer Group of diseases Due to the uncontrolled division of cells
May cause tissue damage by: blocking passageways, e.g. in the gut destroying nerves eroding bone
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This benign mole on the skin has a regular appearance and coloration.
Distinct from benign tumors because they spread and infiltrate the tissues around them. This benign mole on the skin has a regular appearance and coloration. A malignant melanoma (skin cancer) is assymetrical, with an irregular border, and an uneven color.
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Cancer Is An Old Disease
Cancer is not a new disease; it has been detected in the remains off human bodies buried thousands of years ago. Cancer is not restricted to the human species. Most other animals suffer from cancer. Evidence of it has even been found in the fossilized bones of dinosaurs.
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White blood cells (leukocytes)
Types of Cancer Carcinoma The most common form of cancer. Arises from the cells forming skin, the glands (such as the prostate and mammary), the uterus, and the membranes of the respiratory and gastro-intestinal tracts. Carcinomas spread through lymph vessels. Lymphatic cancer Malignant tumor of the lymph tissue. Spreads to other parts of the body through lymph vessels. Sarcoma Malignant tumor arising in connective tissues, such as muscle, bone, cartilage, and the tissue covering muscles and fat. Spread through blood vessels. Osteosarcoma of the foot White blood cells (leukocytes) Leukemia Cancer of the tissues that form blood in the bone marrow. Characterized by uncontrolled production and accumulation of abnormal white blood cells.Spreads through blood and lymph vessels.
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The Incidence of Cancer
The likelihood of developing cancer varies with age. Although the incidence of cancer appears to be greater in humans in recent times, this may simply be because more people are living to an older age and are therefore more likely to develop cancer. Percentage age related incidence of cancer Percentage of people getting cancer
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Susceptibility to Cancer
A person’s susceptibility to cancer is determined by: Chemicals Viruses Familial (inherited) factors Alcohol and diet Ionizing radiation Smoking
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Cancer Cells The growth of a cancer begins when:
Normal cell The growth of a cancer begins when: The genes controlling cell growth and multiplication are transformed into oncogenes by agents called carcinogens. Oncogenes increase the change of a normal cell developing into a tumor cell and increase the malignancy of tumor cells. The oncogenes are passed on to all offspring cells. A small group of abnormal cells is established, and these divide more rapidly than the surrounding cells. Cancer cells are generally undifferentiated. (i.e. they no longer perform the specialized function of their host tissue). Years may pass before the cancer cells multiply enough to disrupt normal bodily function and cause symptoms. Carcinogens Cell seems normal but is predisposed to proliferate excessively Cell begins to proliferate too much, but otherwise normal Cell undergoes structural changes Cell looks obviously abnormal and grows uncontrollably Malignant cell
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Features of a Cancer Cell
Metabolism may be disturbed and the cell ceases to function in its usual way. The bloated, lumpy shape is readily distinguishable from a healthy cell, which has a flat, scaly appearance. Cancer cells may have unusual numbers of chromosomes. Cancer cells can go on dividing indefinitely if they have a continual supply of nutrients. They are said to be immortal. Cancerous cells lose their attachments to neighboring cells.
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Cancer Symptoms The vast array of symptoms produced by the many different kinds of cancers depends on: site of growth tissue of origin extent of the growth Symptoms may include: lumps (the growth of tumors) bleeding disruption of function of the organ affected. T K Photo: CDC Renal carcinoma Note how much of the normal kidney tissue (K) has been replaced by gray and yellow tumor tissue (T).
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Cancer Symptoms Severe recurrent headaches Persistent hoarseness
Difficulty swallowing Coughing up bloody phlegm Lump or change in breast shape, bleeding or discharge from nipple Persistent abdominal pain Change in shape/size of testes. Vaginal bleeding/spotting between periods or after menopause Blood in urine, with no pain on urination. Change in bowel habits Blemish or mole that enlarges, bleeds, or itches Rapid weight loss without an apparent cause Sore, scab, or ulcer that fails to heal within 3 weeks
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Treating Cancer The treatment of cancer is primarily surgical as removal of a tumor may often be a complete cure. If the tumor cannot be surgically removed, or it is likely that metastases remain after surgery, the patient will be treated using: radiotherapy and/or chemotherapy Chemotherapy Radiotherapy
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Common side effects of chemotherapy
Hair loss Chemotherapy is the treatment of cancer by drugs that act selectively on the cancer cells. Anticancer drugs act either by: destroying tumor cells or stopping them from multiplying Unfortunately, the drugs used in these treatments may also detrimentally affect many normal tissues because they act on all rapidly dividing cells, not just tumor cells. Oral ulcers Reduced white blood cell production Thinning of the intestinal lining No gamete production
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A linear accelerator used for radiotherapy
Ionizing radiation (normally a source of damage to DNA) is used to treat cancer tumors. As radiation passes through diseased tissue, it destroys or slows the development of abnormal cells. With the correct dosage of radiation, normal cells suffer very little and there is no long-term damage. Side effects are usually short-lived and involve minor burning of the skin or some localized hair loss. A linear accelerator used for radiotherapy Radiation generator Patient lies on adjustable table Machine can be tilted to allow radiation of the tumor from various directions
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The three oldest methods
The Truth About Cancer The three oldest methods
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Breast Cancer Breast cancer is the most common cancer in women in the developed world (1 in every 3 cancer diagnoses). One woman in eight develops breast cancer. One third of these women die of the disease. Approximately 1% of cases occur in men. Like all cancers, the incidence of breast cancer increases with age. It is almost unknown before age 25,but the incidence rises markedly in the age group. Most deaths from breast cancer occur because the disease has already spread (metastasized) beyond the breast. Once the cancer has metastasized, average survival time is 2 years. Age related incidence of breast cancer in women Data: BreastScreen Victoria
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Causes of Breast Cancer
About 70% of breast cancer cases are thought to be estrogen related because the incidence of breast cancer is higher in women: where menstruation began early where menopause was late with no children, or late age for the first pregnancy There is a definite inherited susceptibility: women with mothers or sisters that have had breast cancer are at greater risk. A link between breast cancer and high fat intake is suggested but not well established. In Japan, where a low-fat diet predominates, the disease is rare. Yet Japanese women living in the United States and eating a higher-fat diet have the same rate of breast cancer as American women generally. There is a familial susceptibility to breast cancer A traditional Japanese diet is low in fat
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Fat deposits Cancer cells may detach from the tumor mass and enter the blood vessels and lymph ducts where they can form secondary tumors. Cancer: Malignant tumor of the breast tissue. Cysts: fluid filled sacs not associated with cancer. Nipple Fibroadenoma: One of a number of common benign tumors.
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Detecting Breast Cancer
Regular self-examination to detect lumps in the breast tissue is the primary method of detection. If cancer is discovered, X-rays, ultrasound scanning, and blood tests will determine if the disease has spread to other parts of the body. Mammography is a common detection method and involves an X-ray of the breast. Mammography can detect tumors less than 1.5 cm in diameter. Where there is a possibility that a lump may be a malignant tumor, a biopsy will be performed. In a biopsy, a sample of the affected breast tissue is taken with a hollow needle and examined under a microscope. Breast self-examination is a recommended practice for women
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Treatment of Breast Cancer
Surgical removal of a tumor achieves a cure (as defined by survival for 20 years) in one third of women with early breast cancer. Lumpectomy: only the area of cancerous tissue is removed. Quadrantectomy: Removal of the tumor plus a wedge of surrounding tissue. Radical mastectomy: removal of the entire breast, chest muscle, associated lymph nodes, and fat and skin.
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A large elliptical incision is made encompassing the entire breast.
All the breast tissue including the skin and some of the fat, is removed, down to the level of the muscle. This is done to ensure that all of the cancerous tissue is removed. All bleeding vessels are tied off and drainage tubes are inserted.
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