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Breast cancer is a kind of cancer that develops from breast cells.
Breast cancer usually starts off in the inner lining of milk ducts or the lobules that supply them with milk. A malignant tumor can spread to other parts of the body. A breast cancer that started off in the lobules is known as lobular carcinoma, while one that developed from the ducts is called ductal carcinoma.
Breast cancer is the most common invasive cancer in females worldwide. It accounts for 16% of all female cancers and 22.9% of invasive cancers in women. 18.2% of all cancer deaths worldwide, including both males and females, are from breast cancer.
Breast cancer rates are much higher in developed nations compared to developing ones. There are several reasons for this, with possibly life-expectancy being one of the key factors - breast cancer is more common in elderly women; women in the richest countries live much longer than those in the poorest nations. The different lifestyles and eating habits of females in rich and poor countries are also contributory factors, experts believe.
According to the National Cancer Institute, 232,340 female breast cancers and 2,240 male breast cancers are reported in the USA each year, as well as about 39,620 deaths caused by the disease.
Contents of this article:
The anatomy of a female breast
1. Chest wall. 2. Pectoralis muscles. 3. Lobules (glands that make milk). 4. Nipple surface. 5. Areola. 6. Lactiferous duct tube that carries milk to the nipple. 7. Fatty tissue. 8. Skin.
Image by Patrick J. Lynch and Morgoth666
A mature human female's breast consists of fat, connective tissue and thousands of lobules - tiny glands which produce milk. The milk of a breastfeeding mother goes through tiny ducts (tubes) and is delivered through the nipple.
The breast, like any other part of the body, consists of billions of microscopic cells. These cells multiply in an orderly fashion - new cells are made to replace the ones that died.
In cancer, the cells multiply uncontrollably, and there are too many cells, progressively more and more than there should be.
Cancer that begins in the lactiferous duct (milk duct), known as ductal carcinoma, is the most common type. Cancer that begins in the lobules, known as lobular carcinoma, is much less common.
Recent developments on breast cancer diagnosis
A new study suggests it may be possible to detect the early signs of breast cancer with a test that measures changes in zinc isotopes. The researchers, led by scientists from the University of Oxford in the UK, report their findings in the journal Metallomics.
According to a new study published in the journal Radiology, magnetic resonance imaging scans may help predict which women are most likely to develop breast cancer in the future.
An international group of independent breast cancer experts have met to evaluate the benefits of different methods of screening for breast cancer, arriving at the conclusion that mammography is best for reducing breast cancer mortality in women aged over 50.
A test that identifies genetic information in the blood picks up sensitive amounts of DNA that can be used to shape decisions about cancer treatment.
Symptoms of breast cancer
A symptom is only felt by the patient, and is described to the doctor or nurse, such as aheadache or pain. A sign is something the patient and others can detect, for example, a rash or swelling.
The first symptoms of breast cancer are usually an area of thickened tissue in the woman's breast, or a lump. The majority of lumps are not cancerous; however, women should get them checked by a health care professional.
Women who detect any of the following signs or symptoms should tell their doctor (NHS, UK):
- A lump in a breast
- A pain in the armpits or breast that does not seem to be related to the woman's menstrual period
- Pitting or redness of the skin of the breast; like the skin of an orange
- A rash around (or on) one of the nipples
- A swelling (lump) in one of the armpits
- An area of thickened tissue in a breast
- One of the nipples has a discharge; sometimes it may contain blood
- The nipple changes in appearance; it may become sunken or inverted
- The size or the shape of the breast changes
- The nipple-skin or breast-skin may have started to peel, scale or flake.
Causes of breast cancer?
Experts are not definitively sure what causes breast cancer. It is hard to say why one person develops the disease while another does not. We know that some risk factors can impact on a woman's likelihood of developing breast cancer. These are:
- Getting older - the older a woman gets, the higher is her risk of developing breast cancer; age is a risk factor. Over 80% of all female breast cancers occur among women aged 50+ years (after the menopause).
- Genetics - women who have a close relative who has/had breast or ovarian cancer are more likely to develop breast cancer. If two close family members develop the disease, it does not necessarily mean they shared the genes that make them more vulnerable, because breast cancer is a relatively common cancer.
The majority of breast cancers are not hereditary.
Women who carry the BRCA1 and BRCA2 genes have a considerably higher risk of developing breast and/or ovarian cancer. These genes can be inherited. TP53, another gene, is also linked to greater breast cancer risk. - A history of breast cancer - women who have had breast cancer, even non-invasive cancer, are more likely to develop the disease again, compared to women who have no history of the disease.
- Having had certain types of breast lumps - women who have had some types of benign (non-cancerous) breast lumps are more likely to develop cancer later on. Examples include atypical ductal hyperplasia or lobular carcinoma in situ.
- Dense breast tissue - women with more dense breast tissue have a greater chance of developing breast cancer.
- Estrogen exposure - women who started having periods earlier or entered menopause later than usual have a higher risk of developing breast cancer. This is because their bodies have been exposed to estrogenfor longer. Estrogen exposure begins when periods start, and drops dramatically during the menopause.
- Obesity - post-menopausal obese and overweight women may have a higher risk of developing breast cancer. Experts say that there are higher levels of estrogen in obese menopausal women, which may be the cause of the higher risk.
- Height - taller-than-average women have a slightly greater likelihood of developing breast cancer than shorter-than-average women. Experts are not sure why.
- Alcohol consumption - the more alcohol a woman regularly drinks, the higher her risk of developing breast cancer is. The Mayo Clinicsays that if a woman wants to drink, she should not exceed one alcoholic beverage per day.
- Radiation exposure - undergoing X-rays andCT scans may raise a woman's risk of developing breast cancer slightly. Scientists at the Memorial Sloan-Kettering Cancer Center found that women who had been treated with radiation to the chest for a childhood cancer have a higher risk of developing breast cancer.
- HRT (hormone replacement therapy) - both forms, combined and estrogen-only HRTtherapies may increase a woman's risk of developing breast cancer slightly. Combined HRT causes a higher risk.
- Certain jobs - French researchers found thatwomen who worked at night prior to a first pregnancy had a higher risk of eventually developing breast cancer.
Canadian researchers found that certain jobs, especially those that bring the human body into contact with possible carcinogens and endocrine disruptors are linked to a higher risk of developing breast cancer. Examples include bar/gambling, automotive plastics manufacturing, metal-working, food canning and agriculture. They reported their findings in the November 2012 issue of Environmental Health. - Cosmetic implants may undermine breast cancer survival - women who have cosmetic breast implants and develop breast cancer may have a higher risk of dying prematurely form the disease compared to other females, researchers from Canada reported in the BMJ (British Medical Journal) (May 2013 issue).
The team looked at twelve peer-reviewed articles on observational studies which had been carried out in Europe, the USA and Canada.
Experts had long-wondered whether cosmetic breast implants might make it harder to spot malignancy at an early stage, because they produce shadows on mammograms.
In this latest study, the authors found that a woman with a cosmetic breast implant has a 25% higher risk of being diagnosed with breast cancer when the disease has already advanced, compared to those with no implants.
Women with cosmetic breast implants who are diagnosed with breast cancer have a 38% higher risk of death from the disease, compared to other patients diagnosed with the same disease who have no implants, the researchers wrote.
After warning that there were some limitations in the twelve studies they looked at, the authors concluded "Further investigations are warranted into the long term effects of cosmetic breast implants on the detection and prognosis of breast cancer, adjusting for potential confounders."
Recent developments on breast cancer causes from MNT news
Collaboration between dozens of worldwide cancer research institutes has added to the ever-improving understanding of breast cancer genetics and personal profiling of the disease by unearthing two new genetic variants associated with a higher risk for the women carrying them.
Breastfeeding is associated with a 30% overall decreased risk of breast cancer recurrence among women who have previously had one subtype of the disease, according to a new study published in theJournal of the National Cancer Institute.
During the 1960s, the pesticide DDT was in widespread use around the globe. Though the chemical is now banned from use in the US and many other countries due to health concerns, a new study finds women who were exposed to higher levels of the chemical in utero more than 50 years ago may be at almost fourfold increased risk of breast cancer than women exposed to lower levels.
The odds of a woman developing breast cancer is significantly higher if bovineleukemia virus is present, a new study suggests. These odds, researchers say, are far higher than with other common risk factors associated with breast cancer, such as obesity, alcohol consumption or the use of postmenopausal hormones.
Invasive and non-invasive breast cancer
Invasive breast cancer - the cancer cells break out from inside the lobules or ducts and invade nearby tissue. With this type of cancer, the abnormal cells can reach the lymph nodes, and eventually make their way to other organs (metastasis), such as the bones, liver or lungs. The abnormal (cancer) cells can travel through the bloodstream or the lymphatic system to other parts of the body; either early on in the disease, or later.
Non-invasive breast cancer - this is when the cancer is still inside its place of origin and has not broken out. Lobular carcinoma in situ is when the cancer is still inside the lobules, while ductal carcinoma in situ is when they are still inside the milk ducts. "In situ" means "in its original place". Sometimes, this type of breast cancer is called "pre-cancerous"; this means that although the abnormal cells have not spread outside their place of origin, they can eventually develop into invasive breast cancer.
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