breast cancer breast cancer breast cancer is cancer that develops from breast tissue. signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, milk rejection, fluid coming from the nipple, a newly inverted nipple, or a red or scaly patch of skin. in those with distant spread of the disease, there may be bone pain, swollen lymph nodes, shortness of breath, or yellow skin. breast canceran illustration of breast cancerspecialtyoncologysymptomsa lump in a breast, a change in breast shape, dimpling of the skin, fluid from the nipple, a newly inverted nipple, a red scaly patch of skin on the breastrisk factorsbeing female, obesity, lack of exercise, alcohol, hormone replacement therapy during menopause, ionizing radiation, early age at first menstruation, having children late in life or not at all, older age, prior breast cancer, family history of breast cancer, klinefelter syndromediagnostic methodtissue biopsy mammographytreatmentsurgery, radiation therapy, chemotherapy, hormonal therapy, targeted therapyprognosisfive-year survival rate ≈85% (us, uk)frequency2.2 million affected (global, 2020)deaths685,000 (global, 2020) risk factors for developing breast cancer include obesity, a lack of physical exercise, alcoholism, hormone replacement therapy during menopause, ionizing radiation, an early age at first menstruation, having children late in life or not at all, older age, having a prior history of breast cancer, and a family history of breast cancer. about 5–10% of cases are the result of an inherited genetic predisposition, including brca mutations among others. breast cancer most commonly develops in cells from the lining of milk ducts and the lobules that supply these ducts with milk. cancers developing from the ducts are known as ductal carcinomas, while those developing from lobules are known as lobular carcinomas. there are more than 18 other sub-types of breast cancer. some, such as ductal carcinoma in situ, develop from pre-invasive lesions. the diagnosis of breast cancer is confirmed by taking a biopsy of the concerning tissue. once the diagnosis is made, further tests are done to determine if the cancer has spread beyond the breast and which treatments are most likely to be effective. the balance of benefits versus harms of breast cancer screening is controversial. a 2013 cochrane review found that it was unclear if mammographic screening does more harm than good, in that a large proportion of women who test positive turn out not to have the disease. a 2009 review for the us preventive services task force found evidence of benefit in those 40 to 70 years of age, and the organization recommends screening every two years in women 50 to 74 years of age. the medications tamoxifen or raloxifene may be used in an effort to prevent breast cancer in those who are at high risk of developing it. surgical removal of both breasts is another preventive measure in some high risk women. in those who have been diagnosed with cancer, a number of treatments may be used, including surgery, radiation therapy, chemotherapy, hormonal therapy, and targeted therapy. types of surgery vary from breast-conserving surgery to mastectomy. breast reconstruction may take place at the time of surgery or at a later date. in those in whom the cancer has spread to other parts of the body, treatments are mostly aimed at improving quality of life and comfort. outcomes for breast cancer vary depending on the cancer type, the extent of disease, and the person's age. the five-year survival rates in england and the united states are between 80 and 90%. in developing countries, five-year survival rates are lower. worldwide, breast cancer is the leading type of cancer in women, accounting for 25% of all cases. in 2018, it resulted in 2 million new cases and 627,000 deaths. it is more common in developed countries and is more than 100 times more common in women than in men. signs and symptoms breast cancer showing an inverted nipple, lump, and skin dimpling early signs of possible breast cancer breast cancer most commonly presents as a lump that feels different from the rest of the breast tissue. more than 80% of cases are discovered when a person detects such a lump with the fingertips. the earliest breast cancers, however, are detected by a mammogram. lumps found in lymph nodes located in the armpits may also indicate breast cancer. indications of breast cancer other than a lump may include thickening different from the other breast tissue, one breast becoming larger or lower, a nipple changing position or shape or becoming inverted, skin puckering or dimpling, a rash on or around a nipple, discharge from nipple/s, constant pain in part of the breast or armpit and swelling beneath the armpit or around the collarbone. pain ("mastodynia") is an unreliable tool in determining the presence or absence of breast cancer, but may be indicative of other breast health issues. another symptom complex of breast cancer is paget's disease of the breast. this syndrome presents as skin changes resembling eczema; such as redness, discoloration or mild flaking of the nipple skin. as paget's disease of the breast advances, symptoms may include tingling, itching, increased sensitivity, burning, and pain. there may also be discharge from the nipple. approximately half the women diagnosed with paget's disease of the breast also have a lump in the breast. inflammatory breast cancer is a rare (only seen in less than 5% of breast cancer diagnosis) yet aggressive form of breast cancer characterized by the swollen, red areas formed on the top of the breast. the visual effects of inflammatory breast cancer is a result of a blockage of lymph vessels by cancer cells. this type of breast cancer is seen in more commonly diagnosed in younger ages, obese women and african american women. as inflammatory breast cancer does not present as a lump there can sometimes be a delay in diagnosis. mammary secretory carcinoma (msc) is a rare form of the secretory carcinomas that occurs exclusively in the breast. it usually develops in adults but in a significant percentage of cases also affects children: msc accounts for 80% of all childhood breast cancers. msc lesions are typically slow growing, painless, small ductal breast tumours that have invaded the tissue around their ducts of origin, often spread to sentinel lymph nodes and/or axillary lymph nodes, but rarely metastasized to distant tissues. these tumours typically have distinctive microscopic features and tumour cells that carry a balanced genetic translocation in which part of the ntrk3 gene is fused to part of the etv6 gene to form a fusion gene, etv6-ntrk3. this fusion gene encodes a chimeric protein termed etv6-ntrk3. the ntrk3 part of etv6-ntrk3 protein has up-regulated tyrosine kinase activity that stimulates two signaling pathways, the pi3k/akt/mtor and mapk/erk pathways, which promote cell proliferation and survival and thereby may contribute to the development of msc. conservative surgery, modified radical mastectomy, and radical mastectomy have been the most frequent procedures used to treat adults, while simple mastectomy, local excision with sentinel lymph node biopsy, and complete axillary dissection have been recommended to treat children with msc. in all cases, long-term, e.g. >20 years, follow-up examinations are recommended. the relatively rare cases of msc that have metastasized to distant tissues have shown little or no responses to chemotherapy and radiotherapy. three patients with metastatic disease had good partial responses to entrectinib, a drug that inhibits the tyrosine kinase activity of the etv6-ntrk3 fusion protein. because of its slow growth and low rate of metastasis to distant tissues, individuals with msc have had 20 year survival rates of 93.16%. in rare cases, what initially appears as a fibroadenoma (hard, movable non-cancerous lump) could in fact be a phyllodes tumour. phyllodes tumours are formed within the stroma (connective tissue) of the breast and contain glandular as well as stromal tissue. phyllodes tumours are not staged in the usual sense; they are classified on the basis of their appearance under the microscope as benign, borderline or malignant. malignant tumours can result in metastatic tumours – secondary tumours (originating from the primary tumour) that spread beyond the site of origination. the symptoms caused by metastatic breast cancer will depend on the location of metastasis. common sites of metastasis include bone, liver, lung, and brain. when cancer has reached such an invasive state, it is categorized as a stage 4 cancer, cancers of this state are often fatal. common symptoms of stage 4 cancer include unexplained weight loss, bone and joint pain, jaundice and neurological symptoms. these symptoms are called non-specific symptoms because they could be manifestations of many other illnesses. rarely breast cancer can spread to exceedingly uncommon sites such as peripancreatic lymph nodes causing biliary obstruction leading to diagnostic difficulties. tumour in the breast visualized by breast-computertomography (breast-ct) most symptoms of breast disorders, including most lumps, do not turn out to represent underlying breast cancer. less than 20% of lumps, for example, are cancerous, and benign breast diseases such as mastitis and fibroadenoma of the breast are more common causes of breast disorder symptoms. risk factors main article: risk factors of breast cancer risk factors can be divided into two categories: modifiable risk factors (things that people can change themselves, such as consumption of alcoholic beverages), and fixed risk factors (things that cannot be changed, such as age and physiological sex). the primary risk factors for breast cancer are being female and older age. other potential risk factors include genetics, lack of childbearing or lack of breastfeeding, higher levels of certain hormones, certain dietary patterns, and obesity. one study indicates that exposure to light pollution is a risk factor for the development of breast cancer. if all adults maintained the healthiest possible lifestyles, including not drinking alcoholic beverages, maintaining a healthy body composition, never smoking, eating healthful food, and other actions, then almost a quarter of breast cancer cases worldwide could be prevented. the remaining three-quarters of breast cancer cases cannot be prevented through lifestyle changes. lifestyle