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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:
1) 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).
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.
3) 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.
4) 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.
5) Dense breast tissue
Women with more dense breast tissue have a greater chance of developing breast cancer.
6) 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 estrogen for longer. Estrogen exposure begins when periods start, and drops dramatically during the menopause.
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.
Taller-than-average women have a slightly greater likelihood of developing breast cancer than shorter-than-average women. Experts are not sure why.
9) Alcohol consumption
The more alcohol a woman regularly drinks, the higher her risk of developing breast cancer is. The Mayo Clinic says that if a woman wants to drink, she should not exceed one alcoholic beverage per day.
10) Radiation exposure
Undergoing X-rays and CT 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.
11) HRT (hormone replacement therapy)
Both forms, combined and estrogen-only HRT therapies may increase a woman's risk of developing breast cancer slightly. Combined HRT causes a higher risk.
12) Certain jobs
French researchers found that women 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
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 the Journal of the National Cancer Institute.
New research published in PLOS ONE finds a link between a protein essential for milk production and an increased metastasis of breast cancer. The protein in question appears to aid breast cancer's advance through two separate pathways.
When it comes to the rising rates of obesity, sugar is deemed a key culprit. But high sugar intake may not only lead to weight gain; a new study claims it can increase the risk of breast cancer and hasten spread of the disease to the lungs.
Each year, tens of thousands of cases of breast cancer in the US and Europe are linked to alcohol consumption, and it is also linked to an increased risk of cancer recurrence in women with early-stage breast cancer. Now, a new study provides a direct link between alcohol, estrogen and a cancer-causing gene.
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.
Diagnosing breast cancer
Women are usually diagnosed with breast cancer after a routine breast cancer screening, or after detecting certain signs and symptoms and seeing their doctor about them.
If a woman detects any of the breast cancer signs and symptoms described above, she should speak to her doctor immediately. The doctor, often a primary care physician (general practitioner, GP) initially, will carry out a physical exam, and then refer the patient to a specialist if he/she thinks further assessment is needed.
Below are examples of diagnostic tests and procedures for breast cancer:
1) Breast exam
The physician will check both the patient's breasts, looking out for lumps and other possible abnormalities, such as inverted nipples, nipple discharge, or change in breast shape. The patient will be asked to sit/stand with her arms in different positions, such as above her head and by her sides.
2) X-ray (mammogram)
Commonly used for breast cancer screening. If anything unusual is found, the doctor may order a diagnostic mammogram.
Breast cancer screening has become a controversial subject over the last few years. Experts, professional bodies, and patient groups cannot currently agree on when mammography screening should start and how often it should occur. Some say routine screening should start when the woman is 40 years old, others insist on 50 as the best age, and a few believe that only high-risk groups should have routine screening.
In July, 2012, The American Medical Association said that women should be eligible for screening mammography from the age of 40, and it should be covered by insurance.
In a Special Report in The Lancet (October 30th, 2012 issue), a panel of experts explained that breast cancer screening reduces the risk of death from the disease. However, they added that it also creates more cases of false-positive results, where women end up having unnecessary biopsies and harmless tumors are surgically removed.
In another study, carried out by scientists at the The Dartmouth Institute for Healthy Policy & Clinical Practice in Lebanon, N.H., and reported in the New England Journal of Medicine (November 2012 issue), researchers found that mammograms do not reduce breast cancer death rates.
3) 2D combined with 3D mammograms
3D mammograms, when used in collaboration with regular 2D mammograms were found to reduce the incidence of false positives, researchers from the University of Sydney's School of Public Health, Australia, reported in The Lancet Oncology.
The researchers screened 7,292 adult females, average age 58 years. Their initial screening was done using 2D mammograms, and then they underwent a combination of 2D and 3D mammograms.
Professor Nehmat Houssami and team found 59 cancers in 57 patients. 66% of the cancers were detected in both 2D and combined 2D/3D screenings. However, 33% of them were only detected using the 2D plus 3D combination.
The team also found that 2D plus 3D combination screenings were linked to a much lower number of false positives. When using just 2D screenings there were 141 false positives, compared to 73 using the 2D plus 3D combination.
Prof. Houssami said "Although controversial, mammography screening is the only population-level early detection strategy that has been shown to reduce breast cancer mortality in randomized trials. Irrespective of which side of the mammography screening debate one supports, efforts should be made to investigate methods that enhance the quality of, and hence potential benefit from, mammography screening.
We have shown that integrated 2D and 3D mammography in population breast-cancer screening increases detection of breast cancer and can reduce false-positive recalls depending on the recall strategy. Our results do not warrant an immediate change to breast-screening practice, instead, they show the urgent need for randomised controlled trials of integrated 2D and 3D versus 2D mammography."
4) Breast ultrasound
This type of scan may help doctors decide whether a lump or abnormality is a solid mass or a fluid-filled cyst.
A sample of tissue from an apparent abnormality, such as a lump, is surgically removed and sent to the lab for analysis. It the cells are found to be cancerous, the lab will also determine what type of breast cancer it is, and the grade of cancer (aggressiveness). Scientists from the Technical University of Munich found that for an accurate diagnosis, multiple tumor sites need to be taken.
6) Breast MRI (magnetic resonance imaging) scan
A dye is injected into the patient. This type of scan helps the doctor determine the extent of the cancer. Researchers from the University of California in San Francisco found that MRI provides a useful indication of a breast tumor's response to pre-surgical chemotherapy much earlier than possible through clinical examination.
Recent developments on breast cancer diagnosis
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.
Breast cancer screening could be made more accurate with the help of an oral pill that "lights up" cancerous tumors. This is according to new research recently presented at the 251st National Meeting & Exposition of the American Chemical Society in San Diego, CA.
Breast cancer staging
Staging describes the extent of the cancer in the patient's body and is based on whether it is invasive or non-invasive, how large the tumor is, whether lymph nodes are involved and how many, and whether it has metastasized (spread to other parts of the body).
A cancer's stage is a crucial factor in deciding what treatment options to recommend, and in determining the patient's prognosis.
Staging is done after cancer is diagnosed. To do the staging, the doctor may order several different tests, including blood tests, a mammogram, a chest X-ray, a bone scan, a CT scan, or a PET scan.
On the next page we look at the available treatments for breast cancer and ways in which you can reduce your chances of getting breast cancer.