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.
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.
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.
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.
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.
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.”
Treatments for breast cancer
A multidisciplinary team will be involved in a breast cancer patient’s treatment. The team may consists of an oncologist, radiologist, specialist cancer surgeon, specialist nurse, pathologist, radiologist, radiographer, and reconstructive surgeon. Sometimes the team may also include an occupational therapist, psychologist, dietitian, and physical therapist.
The team will take into account several factors when deciding on the best treatment for the patient, including:
- The type of breast cancer
- The stage and grade of the breast cancer – how large the tumor is, whether or not it has spread, and if so how far
- Whether or not the cancer cells are sensitive to hormones
- The patient’s overall health
- The age of the patient (has she been through the menopause?)
- The patient’s own preferences.
The main breast cancer treatment options may include:
- Radiation therapy (radiotherapy)
- Biological therapy (targeted drug therapy)
- Hormone therapy
- Lumpectomy – surgically removing the tumor and a small margin of healthy tissue around it. In breast cancer, this is often called breast-sparing surgery. This type of surgery may be recommended if the tumor is small and the surgeon believes it will be easy to separate from the tissue around it.
- Mastectomy – surgically removing the breast. Simple mastectomy involves removing the lobules, ducts, fatty tissue, nipple, areola, and some skin. Radical mastectomy means also removing muscle of the chest wall and the lymph nodes in the armpit.
- Sentinel node biopsy – one lymph node is surgically removed. If the breast cancer has reached a lymph node it can spread further through the lymphatic system into other parts of the body.
- Axillary lymph node dissection – if the sentinel node was found to have cancer cells, the surgeon may recommend removing several nymph nodes in the armpit.
- Breast reconstruction surgery – a series of surgical procedures aimed at recreating a breast so that it looks as much as possible like the other breast. This procedure may be carried out at the same time as a mastectomy. The surgeon may use a breast implant, or tissue from another part of the patient’s body.
Radiation therapy (radiotherapy)
Controlled doses of radiation are targeted at the tumor to destroy the cancer cells. Usually, radiotherapy is used after surgery, as well as chemotherapy to kill off any cancer cells that may still be around. Typically, radiation therapy occurs about one month after surgery or chemotherapy. Each session lasts a few minutes; the patient may require three to five sessions per week for three to six weeks.
The type of breast cancer the woman has will decide what type of radiation therapy she may have to undergo. In some cases, radiotherapy is not needed.
Radiation therapy types include:
- Breast radiation therapy – after a lumpectomy, radiation is administered to the remaining breast tissue
- Chest wall radiation therapy – this is applied after a mastectomy
- Breast boost – a high-dose of radiation therapy is applied to where the tumor was surgically removed. The appearance of the breast may be altered, especially if the patient’s breasts are large.
- Lymph nodes radiation therapy – the radiation is aimed at the axilla (armpit) and surrounding area to destroy cancer cells that have reached the lymph nodes
- Breast brachytherapy – scientists at UC San Diego Moores Cancer Center revealed that patients with early-stage breast cancer in the milk ducts which has not spread, seem to benefit from undergoing breast brachytherapy with a strut-based applicator. This 5-day treatment is given to patients after they have undergone lumpectomy surgery. The researchers found that women who received strut-based breast brachytherapy had lower recurrence rates, as well as fewer and less severe side effects.
Medications are used to kill the cancer cells – these are called cytotoxic drugs. The oncologist may recommend chemotherapy if there is a high risk of cancer recurrence, or the cancer spreading elsewhere in the body. This is called adjuvant chemotherapy.
If the tumors are large, chemotherapy may be administered before surgery. The aim is to shrink the tumor, making its removal easier. This is called neo-adjuvant chemotherapy.
Chemotherapy may also be administered if the cancer has metastasized – spread to other parts of the body. Chemotherapy is also useful in reducing some of the symptoms caused by cancer.
Chemotherapy may help stop estrogen production. Estrogen can encourage the growth of some breast cancers.
Side effects of chemotherapy may include nausea, vomiting, loss of appetite, fatigue, sore mouth, hair loss, and a slightly higher susceptibility to infections. Many of these side effects can be controlled with medications the doctor can prescribe. Women over 40 may enter early menopause.
Hormone therapy (hormone blocking therapy)
Hormone therapy is used for breast cancers that are sensitive to hormones. These types of cancer are often referred to as ER positive (estrogen receptor positive) and PR positive (progesterone receptor positive) cancers. The aim is to prevent cancer recurrence. Hormone blocking therapy is usually used after surgery, but may sometimes be used beforehand to shrink the tumor.
If for health reasons, the patient cannot undergo surgery, chemotherapy or radiotherapy, hormone therapy may be the only treatment she receives.
Hormone therapy will have no effect on cancers that are not sensitive to hormones.
Hormone therapy usually lasts up to five years after surgery.
The following hormone therapy medications may be used:
- Tamoxifen – prevents estrogen from binding to ER-positive cancer cells. Side effects may include changes in periods, hot flashes, weight gain, headaches, nausea, vomiting, fatigue, and aching joints.
- Aromatase inhibitors – this type of medication may be offered to women who have been through the menopause. It blocks aromatase. Aromatase helps estrogen production after the menopause. Before the menopause, a woman’s ovaries produce estrogen. Examples of aromatase inhibitors include letrozole, exemestane, and anastrozole. Side effects may include nausea, vomiting, fatigue, skin rashes, headaches, bone pain, aching joints, loss of libido, sweats, and hot flashes.
Ovarian ablation or suppression
- – pre-menopausal women produce estrogen in their ovaries. Ovarian ablation or suppression stop the ovaries from producing estrogen. Ablation is done either through surgery or radiation therapy – the woman’s ovaries will never work again, and she will enter the menopause early.
- A luteinising hormone-releasing hormone agonist (LHRHa) drug called Goserelin will suppress the ovaries. The patient’s periods will stop during treatment, but will start again when she stops taking Goserelin. Women of menopausal age (about 50 years) will probably never start having periods again. Side effects may include mood changes, sleeping problems, sweats, and hot flashes.
Biological treatment (targeted drugs)
- Trastuzumab (Herceptin) – this monoclonal antibody targets and destroys cancer cells that are HER2-positive. Some breast cancer cells produce large amounts of HER2 (growth factor receptor 2); Herceptin targets this protein. Possible side effects may include skin rashes, headaches, and/or heart damage.
- Lapatinib (Tykerb) – this drug targets the HER2 protein. It is also used for the treatment of advanced metastatic breast cancer. Tykerb is used on patients who did not respond well to Herceptin. Side effects include painful hands, painful feet, skin rashes, mouth sores, extreme tiredness, diarrhea, vomiting, and nausea.
- Bevacizumab (Avastin) – stops the cancer cells from attracting new blood vessels, effectively causing the tumor to be starved of nutrients and oxygen. Side effects may include congestive heart failure, hypertension (high blood pressure), kidney damage, heart damage, blood clots, headaches, mouth sores. Although not approved by the FDA for this use, doctors may prescribe it “off-label”. Using this drug for breast cancer is controversial. In 2011, the FDA said that Avastin is neither effective nor safe for breast cancer.
- Low dose aspirin – research carried out on laboratory mice and test tubes has suggested that regular low-dose aspirin may halt the growth and spread of breast cancer. Cancer campaigners cautioned that although the current results show great promise, this research is at a very early stage and has yet to be shown to be effective on humans.