Uncontrolled multiplication of abnormal cells.
Cancerous cells and tissues have abnormal growth rates, shapes, sizes, and functioning. Cancer may progress in stages from a localized tumour (confined to the site of origin) to direct extension (spread into nearby tissue or lymph nodes) and metastasis (spread to more distant sites via the blood or lymphatic system). This malignant growth pattern distinguishes cancerous tumours from benign ones. Cancer is also classified by grade, the extent to which cell characteristics remain specific to their tissue of origin. Both stage and grade affect the chances of survival. Genetic factors and immune status affect susceptibility. Triggers include hormones, viruses, smoking, diet, and radiation. Cancer can begin in almost any tissue, including blood (see leukemia) and lymph (see lymphoma). When it metastasizes, it remains a cancer of its tissue of origin. Early diagnosis and treatment increase the chance of cure. Treatment may include chemotherapy, surgery, and radiation therapy. See also bladder cancer; breast cancer; carcinogen; colorectal cancer; Kaposi sarcoma; laryngeal cancer; lung cancer; ovarian cancer; pancreatic cancer; prostate cancer; skin cancer; stomach cancer; uterine cancer.
colorectal cancer
Malignant tumour of the large intestine (colon) or rectum.
Risk factors include age (after age 50), family history of colorectal cancer, chronic inflammatory bowel diseases, benign polyps, physical inactivity, and a diet high in fat. Many of the symptoms are associated with abnormal digestion and elimination. Colorectal cancer is treated by surgery, chemotherapy, or radiation therapy.
breast cancer
Malignant tumour in a breast, usually in women after menopause.
Risk factors include family history of breast cancer, prolonged menstruation, late first pregnancy (after age 30), obesity, alcohol use, and some benign tumours. Most breast cancers are adenocarcinomas. Any lump in the breast needs investigation because it may be cancer. Treatment may begin with radical or modified mastectomy or lumpectomy (in which only the tumour is removed), followed by radiation therapy, chemotherapy, or removal of the ovaries or adrenal glands.
pancreatic cancer
Malignant tumour of the pancreas.
Risk factors include smoking, a diet high in fat, exposure to certain industrial products, and diseases such as diabetes and chronic pancreatitis. Pancreatic cancer is more common in men. Symptoms often do not appear until pancreatic cancer is advanced; they include abdominal pain, unexplained weight loss, and difficulty digesting fatty foods. Surgery, radiation therapy, chemotherapy, or some combination of these may be used to treat the disease.
lung cancer
Malignant tumour of the lung.
Four major types (squamous-cell carcinoma, adenocarcinoma, large-cell carcinoma, and small-cell carcinoma) have roughly equal prevalence. Most cases are due to long-term cigarette smoking. Heavy smoking and starting smoking earlier in life increase the risk. Passive inhalation (“secondhand smoke”) is linked to lung cancer in nonsmokers. Other risk factors include exposure to radon or asbestos. Symptoms, including coughing (sometimes with blood), chest pain, and shortness of breath, seldom appear until lung cancer is advanced, when treatment with surgery, chemotherapy, and radiation or some combination of the three is less effective. Most patients die within a year of diagnosis.
ovarian cancer
Risk factors include early age of first menstruation (before age 12), late onset of menopause (after age 52), absence of pregnancy, presence of specific genetic mutations, use of fertility drugs, and personal history of breast cancer. Symptoms such as abdominal swelling, pelvic pressure or pain, and unusual vaginal bleeding often do not appear until ovarian cancer is advanced. Surgery, sometimes followed by chemotherapy or radiation therapy, is an effective treatment for most ovarian cancers.
Bladder cancer
adder.
The most significant risk factor associated with bladder cancer is smoking. Exposure to chemicals called arylamines, which are used in the leather, rubber, printing, and textiles industries, is another risk factor. Most bladder cancers are diagnosed after the age of 60; men are affected more than women. Symptoms include blood in the urine, difficulty urinating, excessive urination, or, more rarely, painful urination. Bladder cancer can be treated with surgery, radiation therapy, or chemotherapy.
SKIN CANCER
Malignant tumour of the skin, including some of the most common human cancers.
Though recognizable at an early stage, it has a significant death rate. Light-skinned people have the highest risk but can reduce it by limiting exposure to sunlight and to ionizing radiation. The most common types arise in the epidermis (outer skin layer) and have become more frequent with the thinning of the atmosphere's ozone layer. The most serious form is melanoma, which is frequently fatal if not treated early with surgery. Cancers arising from the dermis are rare; the best-known is Kaposi sarcoma.
STOMACH CANCER
Malignant tumour of the stomach.
The main risk factors include a diet high in salted, smoked, or pickled foods; Helicobacter pylori infection; tobacco and alcohol use; age (over age 60); and a family history of stomach cancer. Males develop stomach cancer at approximately twice the rate of females. Symptoms may be abdominal pain or swelling, unexplained weight loss, vomiting, and poor digestion. Surgery is the only method for treating stomach cancer, although radiation therapy or chemotherapy may be used in conjunction with surgery or to relieve symptoms.
UTERINE CANCER
Malignant tumour of the uterus.
Cancers affecting the lining of the uterus (endometrium) are the most common cancers of the female reproductive tract. Risk factors include absence of pregnancy, early age of first menstruation (before age 12), late onset of menopause (after age 52), obesity, diabetes, and estrogen replacement therapy. Additional risk factors are a personal history of breast or ovarian cancer, age (over age 40), and a family history of uterine cancer. Whites are more likely to develop uterine cancer than are blacks. The major symptom is vaginal bleeding or discharge. Treatment may begin with simple or radical hysterectomy. Some uterine cancers are treated in part by hormonal therapy, radiation therapy, or chemotherapy.
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