Breast cancer is the most common type of cancer in women, and it’s also one of the leading causes of death for American women. Breast cancer typically starts in the cells that line milk-producing glands or other types of breast tissue. Based on their tissue of origin, these cancers can be classified into two primary categories – invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC). IDC is more common than ILC, but both are severe diseases.
This type of cancer can develop in post-pubescent women of any age, in any corner of the world. Statistics in the United States state that 1 in every eight women will be diagnosed with breast cancer in her lifetime.
There have been steady advances in breast cancer research in the last couple of decades. Breast cancer screening tests have become more sensitive and accurate. This has led to detecting breast cancer at early stages, when the disease is still curable.
This blog post will outline everything you need to know about this type of cancer, its risk factors, signs and symptoms, and treatment options.
Breast Cancer Risk Factors
A risk factor is anything that can increase your risk of developing a particular disease, whether it be environmental, genetic or as a result of lifestyle. Here we outline risk factors related to lifestyle (risk factors that can be changed) and those related to biology (risk factors that cannot be changed).
Risk Factors You Can Change
- Drinking alcohol
Having one or more alcoholic drinks per day is a known breast cancer risk factor. Women who have one drink per day have a 10% higher risk of developing breast cancer compared to women who don’t drink at all. Those who have two or more drinks per day increase their risk by 20%.
- Being overweight or obese
Postmenopausal women who are overweight or obese are more likely to develop breast cancer than women whose weight is in the normal range.
- Being physically inactive
The American Cancer Society recommends at least 150 to 300 minutes of moderate physical activity every week (close to or even more than 300 minutes is ideal). This leads to positive changes in the immune system, a lower body weight, and lower levels of hormones, all of which are associated with a lower risk for breast cancer.
- Pregnancy and breastfeeding
Breast cancer research established that women who don’t have children are more likely to develop breast cancer than women who have children. Additionally, women who give birth to their first child later in life (after 30) are at a higher risk of developing breast cancer.
However, breastfeeding for six months or more is linked to lower chances of getting this type of cancer later in life.
- Using birth control
Estrogen from oral contraceptives is a known risk factor for breast cancer, although the cancer risk decreases when a woman stops using oral contraceptives. The effect of other birth control methods (IUDs, vaginal rings, birth control implants, birth control shots, etc.) is still under investigation.
Risk Factors You Cannot Change
- Being born a female
Men can get breast cancer, but it’s far more common in women. Breast cancer is the most frequently diagnosed type of cancer among American females, and because men have less breast tissue than women do, they are at a lower risk for this disease.
- Age group
The older you get, the higher your chances of developing breast cancer. All things being equal, a woman of 25 has a significantly lower chance of developing breast cancer than a woman over 45 years of age.
- Genetic mutations
Specific gene mutations, such as BRCA1 and BRCA2 mutations, are linked to 7-10 % higher chances of developing breast cancer than women without these gene changes. Other gene mutations can also lead to a higher risk of developing breast cancer, but they are rarer.
- Personal and family history of the disease
If a woman has a family member who had or currently has breast cancer (maternal and/or paternal side), her chances of developing this type of cancer increase significantly, especially if this family member is a mother or a sister.
If a woman has had breast cancer in the past, she is more likely to develop it again.
- Radiation therapy to areas near the breast
Radiation therapy to the chest in the past can increase your chances of getting this type of cancer later in life.
Cancer Signs and Symptoms
Breast lumps are the first sign of this type of cancer, but there are other signs that may indicate something is wrong with your breasts. These include:
- Nipple discharge or blood coming from one nipple
- Changes in skin texture (dimpling, puckering, etc.)
- Breast pain that doesn’t go away
- Swelling, redness, or dimpling of the skin in your armpit area (where lymph nodes are)
- Nipple retraction, which means pulling inward instead of sticking out, and more
These symptoms can also point to other conditions, not necessarily breast cancer. If you notice any signs or symptoms, make an appointment with a doctor as soon as possible. Breast self-exams are also helpful for finding potential abnormalities, but they can’t replace routine checkups by medical professionals.
Cancer screening represents a series of tests for early detection when the cancer is not causing any symptoms yet. For breast cancer, women over 40 should get screened every year, especially between the ages of 45 and 54.
Breast cancer screening is typically performed using a mammogram, an imaging test that uses x-rays to visualize the breast tissues. Breast ultrasound is also a common type of screening for cancer. Breast MRI can be used when a mammogram comes back with unclear results or in high-risk women.
If anything abnormal is spotted during screening, women will usually undergo a biopsy, a tissue sample analyzed by a pathologist to identify cancer cells. Breast MRI and ultrasound can also be used for diagnostic purposes instead of or in addition to mammography alone.
To confirm (or deny) a breast cancer diagnosis and determine the stage of the disease, doctors will usually use one or more diagnostic procedures. Breast imaging tests are the standard first step in diagnosing this type of cancer.
Breast mammography is an x-ray that can see the tissue structure inside the breasts and detect potential abnormalities or tumors based on their size and location. Using mammography for diagnostics is not all that different from mammography screening – the doctor will still take x-rays of the breast while the woman is in a prone position.
Magnetic resonance imaging uses magnetic fields and radio waves that let doctors see detailed images of all areas inside the breasts. It is not a standard screening tool, but it can be used when a doctor suspects something is wrong with the breasts.
Compared to the diagnostic procedures outlined above, ultrasound is relatively inexpensive and can be done in an office setting. Breast ultrasound is a painless procedure that doesn’t use radiation. It is typically used in combination with mammography or MRI.
- New technologies
Since the medical community is always striving to provide better care, new technologies are constantly being developed to diagnose and treat breast cancer. For example, MBI or Scintimammography is an imaging test that can detect abnormalities even in dense breast tissue or when implants are present.
Even though new imaging tech can help discover breast cancer early on, it is still important to have a biopsy done to confirm the diagnosis. A biopsy consists of taking a tissue sample of the breast cells. Pathologists then analyze this sample to see if cancer cells are present.
Breast biopsies can be done in different ways:
- Fine needle aspiration (FNA)
- Core needle biopsy
- Surgical biopsy
Alongside a breast biopsy, it might also be required to perform a lymph node biopsy. Breast cancer can spread to the lymph nodes, so this procedure is essential in determining how advanced the disease has become.
After diagnosis and staging (determination of the tumor’s size, location, level of spread, and subtype), a treatment plan can be developed. Breast cancer is often treated surgically, but there are other options: chemotherapy, radiation therapy, hormone therapy, immunotherapy, or targeted therapies – all work by preventing cancer cell growth or killing cancer cells through a variety of biological mechanisms.
Breast Cancer Subtypes
Breast cancers can be classified into subtypes based on specific proteins or receptors that are present on cell surfaces. The three primary breast cancer subtypes include:
- Hormone-receptor-positive cancer – HR-positive breast cancer is the most common type of breast cancer in women. These cancer cells contain receptors for estrogen, progesterone, or both. Breast cancers that are HR-positive account for 70% to 80% of all breast cancer cases in the United States.
- Human epidermal growth factor receptor-2 positive cancer – HER2-positive breast cancer has a specific protein that is present on the surface of cancer cells (called the human epidermal growth factor receptor 2). Breast cancers with high levels of this receptor are more aggressive, which means they have a higher risk for spreading to other parts of the body.
- Triple-negative cancer – Breast cancer cells that don’t contain an estrogen receptor or progesterone receptor, nor do they have a high level of the HER2 protein, are classified as triple-negative.
These three subtypes behave differently (and respond differently to treatment), so it’s essential to classify breast cancer diagnosis.
Breast Cancer Treatment
Two main types of breast cancer surgery exist: breast-conserving surgery and mastectomy.
Breast-conserving surgery is a lumpectomy, which means that only the tumor and a little surrounding tissue are removed from the breast.
In contrast, a mastectomy removes an entire breast (or a large part of it). A mastectomy can be followed by other surgical procedures, such as breast reconstruction surgery.
A form of localized treatment, the radiation includes high-energy waves or particles directed at the tumor to kill cancer cells. Radiation therapy is used in combination with surgery and/or chemotherapy, but it can also be administered independently.
Two types of radiation treatments exist: external beam radiation and brachytherapy (internal radiotherapy). External beam radiation consists of a large machine that delivers a beam of radiation from outside the body. Internal radiotherapy delivers high doses of localized therapy into the tumor.
Radiation can be used before surgery (neoadjuvant) or after surgery (adjuvant radiation therapy) to destroy any remaining cancer cells that may have been left behind during treatment. It is also used to reduce the risk of breast cancer recurrence.
Chemotherapy (chemo) uses powerful chemicals injected into a vein or taken by mouth to kill fast-growing cells. Chemotherapy can damage healthy cells because it targets rapidly dividing cells, which means that it can affect healthy tissues and organs. This is why it is mainly used in treating metastatic breast cancer.
Breast cancers can be treated with neoadjuvant (before surgery) and/or adjuvant (after surgery) chemotherapy.
Chemotherapy drugs most commonly used in breast cancer treatment include:
- Carboplatin (Paraplatin)
- Cisplatin (Platinol, Platinol AQ)
- Cyclophosphamide (Endoxan, Neosar)
- Docetaxel (Taxotere)
- Doxorubicin (Adriamycin)
- Epirubicin (Ellence)
- Fluorouracil (Carac, Efudex)
- Paclitaxel (Taxol), and more
To treat HR-positive tumors, some women can receive hormonal therapy, which blocks the body’s ability to make estrogen or progesterone.
Hormonal therapies include:
- Drugs that block estrogen receptors – Fulvestrant, Toremifene, Tamoxifen
- Drugs that lower estrogen levels – Aromatase inhibitors (AIs), such as Letrozole, Exemestane, Anastrozole
Unlike chemotherapy, targeted therapy uses small molecules to specifically target the cancer cells. The targeted therapy molecules do not cause as many side effects as chemo because they are not as toxic to healthy cells.
Different types of targeted drugs are used based on the breast cancer subtype:
- HER2-positive cancer – antibody-drug conjugates (ado-trastuzumab emtansine, fam-trastuzumab deruxtecan), monoclonal antibodies (trastuzumab, margetuximab, pertuzumab)
- HR-positive cancer – CDK4/6 inhibitors (ribociclib, palbociclib, abemaciclib), PI3K inhibitor (alpelisib), mTOR inhibitor (everolimus)
- Triple-negative cancer – antibody-drug conjugate (sacituzumab govitecan)
Immunotherapy is a treatment option that has started to gain attention in recent years. Immunotherapy stimulates the body’s immune system to recognize and attack cancer cells, which is why it can be used against many different types of cancers.
In July 2021, a drug belonging to a group of immune checkpoint inhibitors called pembrolizumab was approved by the FDA for the treatment of metastatic triple-negative breast cancer.
Immune checkpoint inhibitors work by blocking the interaction between proteins expressed on the surface of cancer cells and immune system T-cells. The interaction between these proteins prevents the body’s immune system from killing cancer cells, which is why the drugs are called “checkpoint” inhibitors.
Breast Cancer Survivorship
The good news is that breast cancer mortality rates have been steadily declining in the last decade. Approximately 80% of breast cancer patients diagnosed with early-stage disease are expected to live at least ten years after diagnosis.
The bad news is that the quality of life of a breast cancer survivor may not be the same as that of someone who has never had cancer. Breast cancer survivors are more likely to have long-term effects from the disease, which can include chronic pain, heart damage due to chemotherapy or radiation treatment in some cases, fatigue, and sexual problems.
Breast cancer patients who have undergone a mastectomy may experience body image issues and emotional distress. Breast reconstruction surgery can help restore a woman’s breast after a mastectomy, but this procedure does not guarantee that all women will be happy with how they feel and look following surgery.
In addition, women who have entered early menopause due to therapy may face a range of challenges, including infertility, osteoporosis, and heart disease.
As in all cases of severe disease, breast cancer survivorship is a complex issue that requires more time to fully understand its effects on survivors’ lives.
A breast cancer diagnosis doesn’t have to be a death sentence. Breast cancer survival rates are steadily climbing thanks to continued research and breakthroughs in treatment options.
Being familiar with the risk factors and getting regularly screened for breast cancer are the best ways to detect the disease early and increase the likelihood that every woman will be able to overcome it.
Treatment options include surgery, chemotherapy, radiation therapy, targeted therapies, immunotherapy, and hormonal therapy. New methods are still being investigated.
Survivors of breast cancer may face certain challenges during their recovery process, which is why they must remain focused on the possibilities for better health in the future.
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