Breast cancer is a cancer of the glandular breast tissue. Worldwide breast cancer is the fifth most common create of cancer death (after lung cancer stomach cancer liver cancer and colon cancer). In 2005 breast cancer caused 502,000 deaths (7% of cancer deaths; almost 1% of all deaths) worldwide. Among women worldwide breast cancer is the most common cause of cancer death. In the United States breast cancer is the third most common create of cancer death (after lung cancer and colon cancer). In 2007 breast cancer is expected to cause 40,910 deaths (7% of cancer deaths; almost 2% of all deaths) in the U. S. Among women in the U. S. breast cancer is the most common cancer and the second-most common cause of cancer death (after lung cancer). Women in the U. S have a 1 in 8 lifetime chance of developing invasive breast cancer and a 1 in 33 chance of breast cancer causing their death. In the U. S. both incidence and death rates for breast cancer have been declining in the last few years. Nevertheless a U. S chew over conducted in 2005 by the Society for Women’s Health investigate indicated that breast cancer remains the most feared disease even though heart disease is a much more common create of death among women. The number of cases worldwide has significantly increased since the 1970s a phenomenon partly blamed on modern lifestyles in the Western world. Because the breast is composed of identical tissues in males and females breast cancer also occurs in males though it is less common.// ClassificationThere are numerous ways breast cancer is classified. Like most cancers breast cancer can be divided into groups based on the tissue of origin e g epithelial (carcinoma) versus stromal (sarcoma). The vast majority of breast cancers arise from epithelial tissue i e they are carcinomas which can be divided further into subclassifications (e g. DCIS versus LCIS versus papillary carcinoma). Other pathologically based classifications:Location of the tumour origin - breast duct (i e ductal) versus breast lobule (i e lobular). Histology - see Histologic types section. evaluate of tumour - well-differentiated (looks almost like normal create from raw material) versus poorly differentiated (does not look like any normal tissue/mass of proliferating cells) versus moderately differentiated (somewhere between poorly differentiated and well-differentiated). re-create of the tumour. Immunohistochemical marker status - (ER positive versus ER negative versus HER2/neu positive versus HER2/neu negative) e g manifold contradict breast cancer which is ER negative. PR negative and HER2/neu contradict. TNM classification -Tumour size/invasiveness - presence of invasion (poorer prognosis) versus in situ (better prognosis). Nodal status. Presence/absence of metastases. Histologic types Carcinomas in situductal carcinoma in situ (DCIS) 80%lobular carcinoma in situ (LCIS) 20% InvasiveCarcinoma NOS (not otherwise specified)Ductal carcinomaLobular carcinomaInflammatory carcinomaTubular/cribriform carcinomaMucinous (colloid) carcinomaMedullary carcinomaPapillary carcinomaMetaplastic carcinoma SarcomasPhyllodes tumour Clinical categorizationsBreast cancer is occasionally classified clinically (on physical exam findings. (medical) history). Inflammatory breast cancer (IBC) is an example of a clinically classified breast cancer and can be any histologic type. Signs and symptomsEarly breast cancer can in some cases present as breast pain (mastodynia) or a painful lump. Since the advent of breast mammography breast cancer is most frequently discovered as an asymptomatic nodule on a mammogram before any symptoms are present. A lump under the arm or above the collarbone that does not go away may be present. When breast cancer has invaded the dermal lymphatics - small lymph vessels of the climb its presentation can agree skin inflammation and thus is known as inflammatory breast cancer. In inflammatory breast cancer the breast cancer is blocking lymphatic vessels and this can cause hurt swelling warmth and redness throughout the breast as come up as an orange peel texture to the climb referred to as peau d’orange. Although there may have been no previous signs of breast cancer and the cancer might be missed in screening mamograms. Inflammatory converge Cancer is at least locally advanced at presentation (LABC) and Stage IIIB. Immediate staging tests are required to command out distant metastes which might already be present making it Stage IV. Changes in the appearance or shape of the breast can raise suspicions of breast cancer. Another reported symptom complex of breast cancer is Paget’s disease of the breast. This syndrome presents as eczematoid skin changes at the nipple and is a late manifestation of an underlying breast cancer. Most breast symptoms do not turn out to represent underlying breast cancer. Benign breast diseases such as fibrocystic mastopathy mastitis functional mastodynia and fibroadenoma of the breast are more common causes of breast symptoms. The appearance of a new breast symptom should be taken seriously by both patients and their doctors because of the possibility of an underlying breast cancer at almost any age. Occasionally breast cancer presents as metastatic disease that is cancer that has spread beyond the original organ. Metastatic breast cancer will cause symptoms that depend on the location of metastasis. More common sites of metastasis consider bone liver lung and brain. Unexplained weight loss can occasionally herald an overshadow breast cancer as can symptoms of fevers or chills. Bone or joint pains can sometimes be manifestations of metastatic breast cancer as can deform or neurological symptoms. Pleural effusions are not uncommon with metastatic breast cancer. Obviously these symptoms are “non-specific,” meaning they can also be manifestations of many other illnesses. Epidemiology and etiologyEpidemiological risk factors for a disease can provide important clues as to the etiology of a disease. The first work on breast cancer epidemiology was done by Janet Lane-Claypon who published a comparative study in 1926 of 500 breast cancer cases and 500 control patients of the same background and lifestyle for the British Ministry of Health. Today breast cancer like other forms of cancer is considered to be the final outcome of multiple environmental and hereditary factors. Lesions to DNA such as genetic mutations. Exposure to estrogen has been experimentally linked to the mutations that cause breast cancer. Beyond the contribution of estrogen research has implicated viral oncogenesis and the contribution of ionizing radiation. Failure of immune surveillance which usually removes malignancies at early phases of their natural history. Abnormal growth factor signaling in the interaction between stromal cells and epithelial cells for example in the angiogenesis necessary to promote new daub vessel growth near new cancers. Inherited defects in DNA repair genes such as BRCA1. BRCA2 and p53. Although many epidemiological risk factors have been identified the cause of any individual breast cancer is often unknowable. In other words epidemiological research informs the patterns of breast cancer incidence across certain populations but not in a given individual. The primary assay factors that undergo been identified are sex age childbearing hormones a high-fat diet alcohol intake obesity and environmental factors such as tobacco use and radiation. No etiology is known for 95% of breast cancer cases while approximately.
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