Signs and symptoms[edit]
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.[15] The earliest breast cancers are detected by a mammogram.[16]Lumps found in lymph nodes located in the armpits[15] 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.[17] Pain ("mastodynia") is an unreliable tool in determining the presence or absence of breast cancer, but may be indicative of other breast health issues.[15][16][18]
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;[15] as inflammatory breast cancer doesn't show as a lump there's sometimes a delay in diagnosis.
Another reported 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 of women diagnosed with Paget's disease of the breast also have a lump in the breast.[19]
In rare cases, what initially appears as a fibroadenoma (hard, movable non-cancerous 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.[20]
Occasionally, breast cancer presents as metastatic disease—that is, cancer that has spread beyond the original organ. The symptoms caused by metastatic breast cancer will depend on the location of metastasis. Common sites of metastasis include bone, liver, lung and brain.[21] Unexplained weight loss can occasionally signal 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.[22]
Most symptoms of breast disorders, including most lumps, do not turn out to represent underlying breast cancer. Fewer than 20% of lumps, for example, are cancerous,[23] 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.[24]
Risk factors[edit]
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 biological sex).[25]
The primary risk factors for breast cancer are female sex and older age.[26] Other potential risk factors include: genetics,[27] lack of childbearing or lack of breastfeeding,[28] higher levels of certain hormones,[29][30] certain dietary patterns, and obesity. Recent studies have indicated that exposure to light pollution is a risk factor for the development of breast cancer.[31]
Lifestyle[edit]
See also: List of breast carcinogenic substances
Smoking tobacco appears to increase the risk of breast cancer, with the greater the amount smoked and the earlier in life that smoking began, the higher the risk.[32] In those who are long-term smokers, the risk is increased 35% to 50%.[32] A lack of physical activity has been linked to ~10% of cases.[33] Sitting regularly for prolonged periods is associated with higher mortality from breast cancer. The risk is not negated by regular exercise, though it is lowered.[34]
There is an association between use of hormonal birth control and the development of premenopausal breast cancer,[25][35] but whether oral contraceptives use may actuallycause premenopausal breast cancer is a matter of debate.[36] If there is indeed a link, the absolute effect is small.[36][37] Additionally it is not clear if the association exists with newer hormonal birth controls.[37] In those with mutations in the breast cancer susceptibility genes BRCA1 or BRCA2, or who have a family history of breast cancer, use of modern oral contraceptives does not appear to affect the risk of breast cancer.[38][39]
The association between breast feeding and breast cancer has not been clearly determined; some studies have found support for an association while others have not.[40] In the 1980s, the abortion–breast cancer hypothesis posited that induced abortion increased the risk of developing breast cancer.[41] This hypothesis was the subject of extensive scientific inquiry, which concluded that neither miscarriages nor abortions are associated with a heightened risk for breast cancer.[42]
There is a relationship between diet and breast cancer, including an increased risk with a high fat diet,[43] alcohol intake,[44] and obesity,[45] related to higher cholesterol levels.[46]Dietary iodine deficiency may also play a role.[47]
Other risk factors include radiation,[48] and shift-work.[49] A number of chemicals have also been linked including: polychlorinated biphenyls, polycyclic aromatic hydrocarbons,organic solvents[50] and a number of pesticides.[51] Although the radiation from mammography is a low dose, it is estimated that yearly screening from 40 to 80 years of age will cause approximately 225 cases of fatal breast cancer per million women screened.[52]
Genetics[edit]
Some genetic susceptibility may play a minor role in most cases.[53] Overall, however, genetics is believed to be the primary cause of 5–10% of all cases.[54] 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.[55] 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.[56]
In less than 5% of cases, genetics plays a more significant role by causing a hereditary breast–ovarian cancer syndrome.[53] This includes those who carry the BRCA1 andBRCA2 gene mutation.[53] These mutations account for up to 90% of the total genetic influence with a risk of breast cancer of 60–80% in those affected.[54] Other significant mutations include: p53 (Li–Fraumeni syndrome), PTEN (Cowden syndrome), and STK11 (Peutz–Jeghers syndrome), CHEK2, ATM, BRIP1, and PALB2.[54] In 2012, researchers said that there are four genetically distinct types of the breast cancer and that in each type, hallmark genetic changes lead to many cancers.[57]
Medical conditions[edit]
Breast changes like atypical ductal hyperplasia[58] and lobular carcinoma in situ,[59][60][61] found in benign breast conditions such as fibrocystic breast changes, are correlated with an increased breast cancer risk. Diabetes mellitus might also increase the risk of breast cancer.[62]
No comments:
Post a Comment