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Metastatic breast cancer, also referred to as metastases, advanced breast cancer, secondary tumours, secondaries or stage 4 breast cancer, is a stage of breast cancer where the disease has spread to distant sites beyond the axillary lymph nodes. There is no cure for breast cancer. There is no stage after IV. It usually occurs several years after the primary breast cancer, although it is sometimes diagnosed at the same time as the primary breast cancer or, rarely, before the primary breast cancer has been diagnosed.〔 Metastatic breast cancer cells frequently differ from the preceding primary breast cancer in properties such as receptor status. The cells have often developed resistance to several lines of previous treatment and have acquired special properties that permit them to metastasize to distant sites. Metastatic breast cancer can be treated, sometimes for many years, but it cannot be cured.〔(【引用サイトリンク】url=http://www.breastcancercare.org.uk/breast-cancer-information/about-breast-cancer/secondary-metastatic-breast-cancer )〕 Distant metastases are the cause of about 90% of deaths due to breast cancer.〔Fouad TM, Kogawa T, Liu DD et al. Overall survival differences between patients with inflammatory and noninflammatory breast cancer presenting with distant metastasis at diagnosis. Breast Cancer Res Treat 2015.〕 Breast cancer can metastasize anywhere in body but primarily metastasizes to the bone, lungs, regional lymph nodes, liver and brain, with the most common site being the bone. Treatment of metastatic breast cancer depends on location of the metastatic tumours and includes surgery, radiation, chemotherapy, biological, and hormonal therapy.〔(【引用サイトリンク】publisher=Canadian Cancer Society )〕 Typical environmental barriers in a metastatic event include physical (a basement membrane), chemical (reactive oxygen species or ROS, hypoxia and low pH) and biological (immune surveillance, inhibitory cytokines and regulatory extra-cellular matrix (ECM) peptides) components. Organ-specific anatomic considerations also influence metastasis; these include blood-flow patterns from the primary tumor and the homing ability of cancer cells to certain tissues. The targeting by cancer cells of specific organs is probably regulated by chemo-attractant factors and adhesion molecules produced by the target organ, along with cell-surface receptors expressed by the tumor cells. ==Symptoms== The symptoms produced by metastatic breast cancer vary by the location of the metastases. For instance: *Metastatic disease to the bone causes severe, progressive pain, and, less commonly, pathological fracture, erythema over the affected bone, and swelling. *Metastatic breast cancer to the brain causes the following symptoms: persistent, progressively worsening headache, visual changes, seizures, nausea or vomiting, vertigo, behavioral and personality changes, and increased intracranial pressure. *Metastatic disease to the liver causes jaundice, elevated liver enzymes, abdominal pain, loss of appetite, nausea, and vomiting *Metastatic breast cancer to the lung or pleura causes chronic cough, dyspnea, abnormal chest X-ray, and chest pain. *Other nonspecific systemic symptoms of metastatic breast cancer include fatigue, malaise, weight loss, and poor appetite. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「metastatic breast cancer」の詳細全文を読む スポンサード リンク
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