Breast Cancer

What Is Breast Cancer? What Causes Breast Cancer?

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.

The vast majority of breast cancer cases occur in females. This article focuses on breast cancer in women.
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.

The anatomy of a female breast

Breast anatomy normal scheme
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.

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.

What is the difference between 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.

What are the signs and symptoms of breast cancer?

A symptom is only felt by the patient, and is described to the doctor or nurse, such as a headache 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.

En Breast cancer illustrations Some of the possible early signs of breast cancer
According to the National Health Service, UK, women who detect any of the following signs or symptoms should tell their doctor:
  • 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

What are the causes of breast cancer?

Experts are not 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.

  • 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 estrogen for 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 Clinic says that if a woman wants to drink, she should not exceed one alcoholic beverage per day.

  • 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.

  • 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.

  • 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."
Breast Cancer UK says that up to 1 in 8 women in the UK will experience breast cancer at some point in their lives. The charity says this figure cannot be attributed to genetic and lifestyle factors alone.

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:

  • 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.

  • 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 does reduce 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.

    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), found that mammograms do not reduce breast cancer death rates.

    A team from the University of Copenhagen reported that women who have false-positive mammogram outcomes may suffer long-lasting stress and anxiety, in some cases this can last up to three years. They published their findings in Annals of Family Medicine (March 2013 issue).

    Researchers from the Barbara Ann Karmanos Cancer Institute in Detroit, Michigan, found that breast cancer mortality was higher among older women whose time-lapses between their last mammogram and their breast cancer diagnosis were longer. They presented their findings at the American Association for Cancer Research (AACR) Annual Meeting 2013.

    Team leader, Michael S. Simon, M.D., M.P.H., said "We found that for women age 75 and older, a longer time interval between the last mammogram and the date of breast cancer diagnosis was associated with a greater chance for dying from breast cancer."

  • 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."

  • Breast ultrasound - this type of scan may help doctors decide whether a lump or abnormality is a solid mass or a fluid-filled cyst.

  • Biopsy - 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.

  • 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.
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.  

Staging of Breast Cancer

Stage 0
Very early breast cancer or preinvasive cancer. This type
of cancer has NOT spread within or outside of your
breast (also called in situ or noninvasive cancer).

Stage I
Tumor smaller than 2 cm. (1 inch*). No cancer is found
in lymph nodes in the armpit, or outside the breast.

Stage II
  • Tumor smaller than 2 cm. (1 inch). Cancer is found in
    the lymph nodes in the armpit,
  • Tumor between 2 and 5 cm. (1 and 2 inches). Cancer may
  • or may not be found in the lymph nodes in rhe armpit,
  • Tumor larger than 5 cm. (2 inches). Cancer is nor found
    in the lymph nodes in the armpir.
Stage III
  • Tumor smaller than 5 cm. (2 inches) wirh cancer alsc
    in the lymph nodes that are stuck togerher.
  • Tumor larger than 5 cm. (2 inches), OR cancer is
    attached to other parts of the breast area including
    the chest wall, ribs, and muscles,
Inflammatory breast cancer. In this rare type of cancer,
the skin of the breast is red and swollen.
Stage IV
Tumor has spread to orher parts of rhe body, such as the
bones, lungs, liver, or brain.

* cm. means centimeters. One inch equals 2.5 centimeters. Inches listed above
are not exact measurements.

This information is courtesy of “A Woman’s Guide to Breast Cancer Diagnosis 
and Treatment,” Developed by the California Department of Health Services.

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A recent study by researchers from Brigham and Women’s Hospital and the University of Miami Miller School of Medicine has apparently identified additional hormone receptors which could be targeted to bolster existing treatment methods.

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