BREAST CANCER DEFINITION
Breast cancer is cancer that forms in the cells of the breasts.
After skin cancer, breast cancer is the most common cancer diagnosed in women in the United States.
Breast cancer can occur in both men and women, but it’s far more common in women.
Substantial support for breast cancer awareness and research funding has helped improve the screening and diagnosis and advances in the treatment of breast cancer. Breast cancer survival rates have increased, and the number of deaths steadily has been declining, which is largely due to a number of factors such as earlier detection, a new personalized approach to treatment and a better understanding of the disease.
BREAST CANCER CAUSES
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 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.
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.
BREAST CANCER PATHOPHYSIOLOGY
There are trillions of cells in the body. These cells have a tightly regulated cell cycle that controls their growth, maturity, division and death. During childhood normal cells divide faster to allow the person to grow. Once adulthood is reached the cells divide to replace worn-out cells and to repair injuries. This cell division and growth is controlled by the cellular blue print or DNA and genes that lie within the cell’s nucleus.
Cancer begins when cells in a part of the body start to grow out of control. All types of cancer, irrespective of their origin, occur due to this disturbed growth of cells that leads to formation of tumours and lesions. In addition, the cancer cells possess some rogue like properties:
- They have longer life spans and instead of dying continue to grow and form new, abnormal cells
- Cancer cells can also invade other tissues. This is something that normal cells cannot do. This property is called metastasis.
- Cancer cells grow into tumors that are supplied by a new network of blood vessels. This is called angiogenesis and is unique in maintaining the blood supply and supply of nutrients to the cancer cells.
BREAST CANCER SYMPTOMS
Signs and symptoms of breast cancer may include:
- A breast lump or thickening that feels different from the surrounding tissue
- Bloody discharge from the nipple
- Change in the size, shape or appearance of a breast
- Changes to the skin over the breast, such as dimpling
- A newly inverted nipple
- Peeling, scaling or flaking of the pigmented area of skin surrounding the nipple (areola) or breast skin
- Redness or pitting of the skin over your breast, like the skin of an orange
BREAST CANCER DIAGNOSIS
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 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.
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 NehmatHoussami 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.
BREAST CANCER TREATMENT
Your doctor determines your breast cancer treatment options based on your type of breast cancer, its stage and grade, size, and whether the cancer cells are sensitive to hormones. Your doctor also considers your overall health and your own preferences.
Most women undergo surgery for breast cancer and also receive additional treatment before or after surgery, such as chemotherapy, hormone therapy or radiation.
There are many options for breast cancer treatment, and you may feel overwhelmed as you make complex decisions about your treatment. Consider seeking a second opinion from a breast specialist in a breast center or clinic. Talk to other women who have faced the same decision.
Breast cancer surgery
Operations used to treat breast cancer include:
- Removing the breast cancer (lumpectomy). During lumpectomy, which may be referred to as breast-sparing surgery or wide local excision, the surgeon removes the tumor and a small margin of surrounding healthy tissue. Lumpectomy is typically reserved for smaller tumors.
- Removing the entire breast (mastectomy). Mastectomy is surgery to remove all of your breast tissue. Most mastectomy procedures remove all of the breast tissue — the lobules, ducts, fatty tissue and some skin, including the nipple and areola (simple mastectomy).
In a skin-sparing mastectomy, the skin over the breast is left intact to improve reconstruction and appearance. Depending on the location and size of the tumor, the nipple may also be spared.
- Removing a limited number of lymph nodes (sentinel node biopsy). To determine whether cancer has spread to your lymph nodes, your surgeon will discuss with you the role of removing the lymph nodes that are the first to receive the lymph drainage from your tumor.
If no cancer is found in those lymph nodes, the chance of finding cancer in any of the remaining lymph nodes is small and no other nodes need to be removed.
- Removing several lymph nodes (axillary lymph node dissection). If cancer is found in the sentinel node, your surgeon will discuss with you the role of removing additional lymph nodes in your armpit.
- Removing both breasts. Some women with cancer in one breast may choose to have their other (healthy) breast removed (contralateral prophylactic mastectomy) if they have a very increased risk of cancer in the other breast because of a genetic predisposition or strong family history.
Most women with breast cancer in one breast will never develop cancer in the other breast. Discuss your breast cancer risk with your doctor, along with the benefits and risks of this procedure.
Complications of breast cancer surgery depend on the procedures you choose. Surgery carries a risk of bleeding and infection.
Some women choose to have breast reconstruction after surgery. Discuss your options and preferences with your surgeon.
Consider a referral to a plastic surgeon before your breast cancer surgery. Your options may include reconstruction with a breast implant (silicone or water-filled) or reconstruction using your own tissue. These operations can be performed at the time of your mastectomy or at a later date.
Radiation therapy uses high-powered beams of energy, such as X-rays, to kill cancer cells. Radiation therapy is typically done using a large machine that aims the energy beams at your body (external beam radiation). But radiation can also be done by placing radioactive material inside your body (brachytherapy).
External beam radiation is commonly used after lumpectomy for early-stage breast cancer. Doctors may also recommend radiation therapy to the chest wall after mastectomy for larger breast cancers or cancers that have spread to the lymph nodes.
Side effects of radiation therapy include fatigue and a red, sunburn-like rash where the radiation is aimed. Breast tissue may also appear swollen or more firm. Rarely, more-serious problems may occur, such as damage to the heart or lungs or, very rarely, second cancers in the treated area.
Chemotherapy uses drugs to destroy cancer cells. If your cancer has a high risk of returning or spreading to another part of your body, your doctor may recommend chemotherapy to decrease the chance that the cancer will recur. This is known as adjuvant systemic chemotherapy.
Chemotherapy is sometimes given before surgery in women with larger breast tumors. The goal is to shrink a tumor to a size that makes it easier to remove with surgery.
Chemotherapy is also used in women whose cancer has already spread to other parts of the body. Chemotherapy may be recommended to try to control the cancer and decrease any symptoms the cancer is causing.
Chemotherapy side effects depend on the drugs you receive. Common side effects include hair loss, nausea, vomiting, fatigue and an increased risk of developing infection. Rare side effects can include premature menopause, infertility (if premenopausal), damage to the heart and kidneys, nerve damage, and, very rarely, blood cell cancer.
Hormone therapy — perhaps more properly termed hormone-blocking therapy — is often used to treat breast cancers that are sensitive to hormones. Doctors sometimes refer to these cancers as estrogen receptor positive (ER positive) and progesterone receptor positive (PR positive) cancers.
Hormone therapy can be used after surgery or other treatments to decrease the chance of your cancer returning. If the cancer has already spread, hormone therapy may shrink and control it.
Treatments that can be used in hormone therapy include:
- Medications that block hormones from attaching to cancer cells. Selective estrogen receptor modulator (SERM) medications act by blocking estrogen from attaching to the estrogen receptor on the cancer cells, slowing the growth of tumors and killing tumor cells.
SERMs include tamoxifen, raloxifene (Evista) and toremifene (Fareston).
Possible side effects include hot flashes, night sweats and vaginal dryness. More-significant risks include blood clots, stroke, uterine cancer and cataracts.
- Medications that stop the body from making estrogen after menopause. Called aromatase inhibitors, these drugs block the action of an enzyme that converts androgens in the body into estrogen. These drugs are effective only in postmenopausal women.
Aromatase inhibitors include anastrozole (Arimidex), letrozole (Femara) and exemestane (Aromasin).
Side effects include hot flashes, night sweats, vaginal dryness, joint and muscle pain, as well as an increased risk of bone thinning (osteoporosis).
- A drug that targets estrogen receptors for destruction.The drug fulvestrant (Faslodex) blocks estrogen receptors on cancer cells and signals to the cell to destroy the receptors. Fulvestrant is used in postmenopausal women. Side effects that may occur include nausea, hot flashes and joint pain.
- Surgery or medications to stop hormone production in the ovaries. In premenopausal women, surgery to remove the ovaries or medications to stop the ovaries from making estrogen can be an effective hormonal treatment.
Targeted drug treatments attack specific abnormalities within cancer cells. Targeted drugs used to treat breast cancer include:
- Trastuzumab (Herceptin). Some breast cancers make excessive amounts of a protein called human growth factor receptor 2 (HER2), which helps breast cancer cells grow and survive. If your breast cancer cells make too much HER2, trastuzumab may help block that protein and cause the cancer cells to die. Side effects may include headaches, diarrhea and heart problems.
- Pertuzumab (Perjeta). Pertuzumab targets HER2 and is approved for use in metastatic breast cancer in combination with trastuzumab and chemotherapy. This combination of treatments is reserved for women who haven’t yet received other drug treatments for their cancer. Side effects of pertuzumab may include diarrhea, hair loss and heart problems.
- Ado-trastuzumab (Kadcyla). This drug combines trastuzumab with a cell-killing drug. When the combination drug enters the body, the trastuzumab helps it find the cancer cells because it is attracted to HER2. The cell-killing drug is then released into the cancer cells. Ado-trastuzumab may be an option for women with metastatic breast cancer who’ve already tried trastuzumab and chemotherapy.
- Lapatinib (Tykerb). Lapatinib targets HER2 and is approved for use in advanced or metastatic breast cancer. Lapatinib can be used in combination with chemotherapy or hormone therapy. Potential side effects include diarrhea, painful hands and feet, nausea, and heart problems.
- Bevacizumab (Avastin). Bevacizumab is no longer approved for the treatment of breast cancer in the United States. Research suggests that although this medication may help slow the growth of breast cancer, it doesn’t appear to increase survival times.