Breast cancer is a type of cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk.
Cancers originating from ducts are known as ductal carcinomas, while those originating from lobules are known as lobular carcinomas.
Breast cancer occurs in humans and other mammals. While the overwhelming majority of human cases occur in women, male breast cancer can also occur.
The benefit versus harms of breast cancer screening is controversial. The characteristics of the cancer determine the treatment, which may include surgery, medications (hormonal therapy and chemotherapy), radiation and/or immunotherapy.
Surgical provides the single largest benefit, and to increase the likelihood of cure, several chemotherapy regimens are commonly given in addition. Radiation is used after breast-conserving surgery and substantially improves local relapse rates and in many circumstances also overall survival.
Worldwide, breast cancer accounts for 22.9% of all cancers (excluding non-melanoma skin cancers) in women.
In 2008, breast cancer caused 458,503 deaths worldwide (13.7% of cancer deaths in women). Breast cancer is more than 100 times more common in women than in men, although men tend to have poorer outcomes due to delays in diagnosis.
Prognosis and survival rates for breast cancer vary greatly depending on the cancer type, stage, treatment, and geographical location of the patient. Survival rates in the Western world are high; for example, more than 8 out of 10 women (84%) in England diagnosed with breast cancer survive for at least 5 years.
In developing countries, however, survival rates are much poorer.
The first noticeable symptom of breast cancer is typically a lump that feels different from the rest of the breast tissue. More than 80% of breast cancer cases are discovered when the woman feels a lump.
The earliest breast cancers are detected by a mammogram. Lumps found in lymph nodes located in the armpits can 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.
Inflammatory breast cancer is a particular type of breast cancer which can pose a substantial diagnostic challenge. Symptoms may resemble a breast inflammation and may include itching, pain, swelling, nipple inversion, warmth and redness throughout the breast, as well as an orange-peel texture to the skin referred to as peau d'orange the absence of a discernible lump delays detection dangerously.
Another reported symptom complex of breast cancer is Paget's disease of the breast. This syndrome presents as eczematoid skin changes such as redness and mild flaking of the nipple skin. As Paget's advances, symptoms may include tingling, itching, increased sensitivity, burning, and pain. There may also be discharge from the nipple. Approximately half of women diagnosed with Paget's also have a lump in the breast.
In rare cases, what initially appears as a fibroadenoma (hard movable lump) could in fact be a phyllodes tumor. Phyllodes tumors are formed within the stroma (connective tissue) of the breast and contain glandular as well as stromal tissue. Phyllodes tumors are not staged in the usual sense; they are classified on the basis of their appearance under the microscope as benign, borderline, or malignant.
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. Common sites of metastasis include bone, liver, lung and brain.
Unexplained weight loss can occasionally herald an occult breast cancer, as can symptoms of fevers or chills. Bone or joint pains can sometimes be manifestations of metastatic breast cancer, as can jaundice or neurological symptoms. These symptoms are called non-specific, meaning they could be manifestations of many other illnesses.
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 cancer and benign breast diseases such as mastitis and fibroadenoma of the breast are more common causes of breast disorder symptoms.
Nevertheless, the appearance of a new symptom should be taken seriously by both patients and their doctors, because of the possibility of an underlying breast cancer at almost any age.
A lack of physical activity has been linked to ~10% of cases.
The association between breast feeding and breast cancer has not been clearly determined with some studies finding support for an association and others not.
In the 1980s the abortion–breast cancer hypothesis posited that induced abortion increased the risk of developing breast cancer. This hypothesis has been the subject of extensive scientific inquiry which has concluded that neither miscarriages nor abortions are associated.
There may be an association between oral contraceptives and the development of premenopausal breast cancer. Whether or not this association is causal is debated and if there is indeed a link the absolute effect is small.
In those with BRCA1 or BRCA2 mutations or a family history modern OCPs do not appear to affect the subsequent risk of breast cancer.
There is a relationship between diet and breast cancer including an increased risk with a high fat diet, alcohol intake, and obesity. Dietary iodine deficiency may also play a role.
Other risk factors include radiation, and shift-work. A number of chemicals have also been linked including: polychlorinated biphenyls, polycyclic aromatic hydrocarbons, organic solvents and a number of pesticides.
Although the radiation from mammography is a low dose, it is estimated that yearly screening from 40 to 80 years of age will cause ~225 cases of fatal breast cancer per million women screened.
In those with zero, one or two affected relatives, the risk of breast cancer before the age of 80 is 7.8%, 13.3%, and 21.1% with a subsequent mortality from the disease of 2.3%, 4.2%, and 7.6% respectively.
In those with a first degree relative with the disease the risk of breast cancer between the age of 40 and 50 is double that of the general population.
In less than 5% of cases, genetics plays a more significant role by causing a hereditary breast–ovarian cancer syndrome. This includes those who carry the BRCA1 and BRCA2 gene mutation.
These mutations account for up to 90% of the total genetic influence with a risk of breast cancer of 60–80% in those affected.
These modifications might prevent 38% of breast cancers in the US, 42% in the UK, 28% in Brazil and 20% in China.
The benefits with moderate exercise such as brisk walking are seen at all age groups including postmenopausal women.
Prophylactic bilateral mastectomy may be considered in people with BRCA1 and BRCA2 mutations.
The selective estrogen receptor modulators (such as tamoxifen) reduce the risk of breast cancer but increase the risk of thromboembolism.
The benefits of breast cancer reduction continues for at least five years after stopping these medications.
As a result, breast cancer is one of the more common cancers found during pregnancy, although it is still rare, because only about 1 in 1,000 pregnant women experience any sort of cancer.
Diagnosing a new cancer in a pregnant woman is difficult, in part because any symptoms are commonly assumed to be a normal discomfort associated with pregnancy.
As a result, cancer is typically discovered at a somewhat later stage than average in many pregnant or recently pregnant women.
Some imaging procedures, such as MRIs (magnetic resonance imaging), CT scans, ultrasounds, and mammograms with fetal shielding are considered safe during pregnancy; some others, such as PET scans are not.
Treatment is generally the same as for non-pregnant women. However, radiation is normally avoided during pregnancy, especially if the fetal dose might exceed 100 cGy.
In some cases, some or all treatments are postponed until after birth if the cancer is diagnosed late in the pregnancy.
Early deliveries to speed the start of treatment are not uncommon. Surgery is generally considered safe during pregnancy, but some other treatments, especially certain chemotherapy drugs given during the first trimester, increase the risk of birth defects and pregnancy loss (spontaneous abortions and stillbirths).
Elective abortions are not required and do not improve the likelihood of the mother surviving or being cured.
Radiation treatments may interfere with the mother's ability to breastfeed her baby because it reduces the ability of that breast to produce milk and increases the risk of mastitis. Also, when chemotherapy is being given after birth, many of the drugs pass through breast milk to the baby, which could harm the baby.
Cancers originating from ducts are known as ductal carcinomas, while those originating from lobules are known as lobular carcinomas.
Breast cancer occurs in humans and other mammals. While the overwhelming majority of human cases occur in women, male breast cancer can also occur.
The benefit versus harms of breast cancer screening is controversial. The characteristics of the cancer determine the treatment, which may include surgery, medications (hormonal therapy and chemotherapy), radiation and/or immunotherapy.
Surgical provides the single largest benefit, and to increase the likelihood of cure, several chemotherapy regimens are commonly given in addition. Radiation is used after breast-conserving surgery and substantially improves local relapse rates and in many circumstances also overall survival.
Worldwide, breast cancer accounts for 22.9% of all cancers (excluding non-melanoma skin cancers) in women.
In 2008, breast cancer caused 458,503 deaths worldwide (13.7% of cancer deaths in women). Breast cancer is more than 100 times more common in women than in men, although men tend to have poorer outcomes due to delays in diagnosis.
Prognosis and survival rates for breast cancer vary greatly depending on the cancer type, stage, treatment, and geographical location of the patient. Survival rates in the Western world are high; for example, more than 8 out of 10 women (84%) in England diagnosed with breast cancer survive for at least 5 years.
In developing countries, however, survival rates are much poorer.
The first noticeable symptom of breast cancer is typically a lump that feels different from the rest of the breast tissue. More than 80% of breast cancer cases are discovered when the woman feels a lump.
The earliest breast cancers are detected by a mammogram. Lumps found in lymph nodes located in the armpits can 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.
Inflammatory breast cancer is a particular type of breast cancer which can pose a substantial diagnostic challenge. Symptoms may resemble a breast inflammation and may include itching, pain, swelling, nipple inversion, warmth and redness throughout the breast, as well as an orange-peel texture to the skin referred to as peau d'orange the absence of a discernible lump delays detection dangerously.
Another reported symptom complex of breast cancer is Paget's disease of the breast. This syndrome presents as eczematoid skin changes such as redness and mild flaking of the nipple skin. As Paget's advances, symptoms may include tingling, itching, increased sensitivity, burning, and pain. There may also be discharge from the nipple. Approximately half of women diagnosed with Paget's also have a lump in the breast.
In rare cases, what initially appears as a fibroadenoma (hard movable lump) could in fact be a phyllodes tumor. Phyllodes tumors are formed within the stroma (connective tissue) of the breast and contain glandular as well as stromal tissue. Phyllodes tumors are not staged in the usual sense; they are classified on the basis of their appearance under the microscope as benign, borderline, or malignant.
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. Common sites of metastasis include bone, liver, lung and brain.
Unexplained weight loss can occasionally herald an occult breast cancer, as can symptoms of fevers or chills. Bone or joint pains can sometimes be manifestations of metastatic breast cancer, as can jaundice or neurological symptoms. These symptoms are called non-specific, meaning they could be manifestations of many other illnesses.
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 cancer and benign breast diseases such as mastitis and fibroadenoma of the breast are more common causes of breast disorder symptoms.
Nevertheless, the appearance of a new symptom should be taken seriously by both patients and their doctors, because of the possibility of an underlying breast cancer at almost any age.
Risk factors
Main article: Risk factors of breast cancer
The primary risk factors for breast cancer are female sex and older age. Other potential risk factors include: lack of childbearing or breastfeeding, higher hormone levels, diet and obesity.Lifestyle
See also: List of breast carcinogenic substances
Smoking
tobacco appears to increase the risk of breast cancer with the greater
the amount smoke and the earlier in life smoking began the higher the
risk. In those who are long term smokers the risk is increased 35% to 50%.A lack of physical activity has been linked to ~10% of cases.
The association between breast feeding and breast cancer has not been clearly determined with some studies finding support for an association and others not.
In the 1980s the abortion–breast cancer hypothesis posited that induced abortion increased the risk of developing breast cancer. This hypothesis has been the subject of extensive scientific inquiry which has concluded that neither miscarriages nor abortions are associated.
There may be an association between oral contraceptives and the development of premenopausal breast cancer. Whether or not this association is causal is debated and if there is indeed a link the absolute effect is small.
In those with BRCA1 or BRCA2 mutations or a family history modern OCPs do not appear to affect the subsequent risk of breast cancer.
There is a relationship between diet and breast cancer including an increased risk with a high fat diet, alcohol intake, and obesity. Dietary iodine deficiency may also play a role.
Other risk factors include radiation, and shift-work. A number of chemicals have also been linked including: polychlorinated biphenyls, polycyclic aromatic hydrocarbons, organic solvents and a number of pesticides.
Although the radiation from mammography is a low dose, it is estimated that yearly screening from 40 to 80 years of age will cause ~225 cases of fatal breast cancer per million women screened.
Genetics
Some genetic susceptibility may play a minor role in most cases. Overall, however, genetics is believed to be the primary cause of 5–10% of all cases.In those with zero, one or two affected relatives, the risk of breast cancer before the age of 80 is 7.8%, 13.3%, and 21.1% with a subsequent mortality from the disease of 2.3%, 4.2%, and 7.6% respectively.
In those with a first degree relative with the disease the risk of breast cancer between the age of 40 and 50 is double that of the general population.
In less than 5% of cases, genetics plays a more significant role by causing a hereditary breast–ovarian cancer syndrome. This includes those who carry the BRCA1 and BRCA2 gene mutation.
These mutations account for up to 90% of the total genetic influence with a risk of breast cancer of 60–80% in those affected.
Medical conditions
Certain breast changes: atypical hyperplasia and lobular carcinoma in situ found in benign breast conditions such as fibrocystic breast changes are correlated with an increased breast cancer risk.Prevention
Women may reduce their risk of breast cancer by maintaining a healthy weight, drinking less alcohol, being physically active and breastfeeding their children.These modifications might prevent 38% of breast cancers in the US, 42% in the UK, 28% in Brazil and 20% in China.
The benefits with moderate exercise such as brisk walking are seen at all age groups including postmenopausal women.
Prophylactic bilateral mastectomy may be considered in people with BRCA1 and BRCA2 mutations.
The selective estrogen receptor modulators (such as tamoxifen) reduce the risk of breast cancer but increase the risk of thromboembolism.
The benefits of breast cancer reduction continues for at least five years after stopping these medications.
Pregnancy
Cancers found during or shortly after pregnancy appear at approximately the same rate as other cancers in women of a similar age.As a result, breast cancer is one of the more common cancers found during pregnancy, although it is still rare, because only about 1 in 1,000 pregnant women experience any sort of cancer.
Diagnosing a new cancer in a pregnant woman is difficult, in part because any symptoms are commonly assumed to be a normal discomfort associated with pregnancy.
As a result, cancer is typically discovered at a somewhat later stage than average in many pregnant or recently pregnant women.
Some imaging procedures, such as MRIs (magnetic resonance imaging), CT scans, ultrasounds, and mammograms with fetal shielding are considered safe during pregnancy; some others, such as PET scans are not.
Treatment is generally the same as for non-pregnant women. However, radiation is normally avoided during pregnancy, especially if the fetal dose might exceed 100 cGy.
In some cases, some or all treatments are postponed until after birth if the cancer is diagnosed late in the pregnancy.
Early deliveries to speed the start of treatment are not uncommon. Surgery is generally considered safe during pregnancy, but some other treatments, especially certain chemotherapy drugs given during the first trimester, increase the risk of birth defects and pregnancy loss (spontaneous abortions and stillbirths).
Elective abortions are not required and do not improve the likelihood of the mother surviving or being cured.
Radiation treatments may interfere with the mother's ability to breastfeed her baby because it reduces the ability of that breast to produce milk and increases the risk of mastitis. Also, when chemotherapy is being given after birth, many of the drugs pass through breast milk to the baby, which could harm the baby.
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