Cancer (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.
Tumour or neoplasm
Mass of abnormal tissue that arises from normal cells, has no useful function, and tends to grow.
- Cell abnormalities may include increased size or number or loss of characteristics that differentiate their tissue of origin.
- Cells in malignant tumours (see cancer) have a distorted size, shape, and/or structure. Less differentiated cells tend to grow faster.
- Malignant tumours invade tissues locally and spread (metastasize) in blood or lymph: the stronger the tendency to metastasize, the more malignant the tumour. Tumours may not cause pain until they press on or invade nerves.
- Both benign and malignant tumours can press on nearby structures, block vessels, or produce excess hormones, all of which can cause death. Benign tumours remain as a solid mass that can be removed by surgery if accessible; they can consist of various tissues and may become malignant; malignant tumours, though they may remain quiescent for a time, never become benign.
Leukemia
Cancer of blood-forming tissues with high levels of leukocytes.
- Radiation exposure and hereditary susceptibility are factors in some cases.
- In acute leukemias, anemia, fever, bleeding, and lymph-node swelling develop rapidly. Acute lymphocytic leukemia, found mostly in children, was once over 90% fatal in six months. Drug therapy can now cure more than half these children. Acute myelogenous (granulocytic) leukemia, found mostly in adults, has frequent remissions and recurrences, and few patients survive long.
- Chronic myelogenous leukemia most often begins in the 40s; weight loss, low fever, weakness, and other symptoms may not develop immediately. Chemotherapy helps the symptoms but may not prolong life.
- Chronic lymphocytic leukemia, mostly in the elderly, may be inactive for years. Survival rates are better than in myelogenous leukemia; most deaths are caused by infection or hemorrhage.
Lymphoma
Any of a group of malignant diseases (see cancer) that usually start in the lymph nodes or lymphoid tissues.
- The two major types
- Hodgkin disease and non-Hodgkin lymphoma, each have several subtypes.
- Diagnosis of either type requires biopsy, usually from the lymph nodes. Non-Hodgkin lymphomas may be diffuse (widespread) or nodular (concentrated in nodules); nodular lymphomas generally develop more slowly.
Prostate Cancer
Malignant tumour of the prostate gland.
Prostate cancer commonly occurs in men over age 50. Symptoms include frequent or painful urination, blood in the urine, sexual dysfunction, swollen lymph nodes in the groin, and pain in the pelvis, hips, back, or ribs. The likelihood of developing prostate cancer doubles if there is a family history. Treatment may include surgery, radiation therapy, hormone therapy, chemotherapy, or a combination of two or more of these approaches.
Mastectomy
- Surgical removal of a breast, usually because of breast cancer.
- If the cancer has spread, radical mastectomy may remove surrounding tissue and/or nearby structures, including chest muscles and lymph nodes. Modified radical mastectomy leaves at least the main chest muscle, has an equally high survival rate, and makes reconstruction easier. Simple mastectomy is removal of the breast only. Lumpectomy is removal of the tumour only.
- 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.
Hodgkin disease or lymphoreticuloma
Most common malignant lymphoma.
It starts with local, painless swelling of lymph nodes and sometimes of the spleen, liver, or other organs, followed by weight loss and weakness.
Diagnosis can be confirmed only by biopsy, usually from a lymph node. The cause remains unknown.
Treatment with chemotherapy, radiation, or both depends on the stage of the disease. More than 90% of patients diagnosed early can be cured, as can many with advanced disease.
Chemotherapy
Treatment of diseases, including cancer, with chemicals.
- Some cancer drugs interfere with cancer-cell division or enzyme processes.
- However, they have serious side effects, attacking some healthy cells and reducing resistance to infection.
- Certain steroids are used to treat breast cancer and prostate cancer, leukemia, and lymphomas. Derivatives of plants such as periwinkle (vincristine, vinblastine) and yew (taxol) have been found effective against Hodgkin disease, leukemia, and breast cancer.
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.
Source:Britannica Encyclopedia
