Breast Cancer


Breast cancer is the most commonly diagnosed cancer, besides skin cancer, found in women in the United States. Treatment advances are leading to more women with breast cancer living longer overall and without disease progression. The following information includes a brief description of how breast cancer develops and is classified, as well as an overview of the disease from diagnosis to follow-up care.

Development, Diagnosis and Classification

Breast cancer develops when one or several abnormal cells divide and multiply to become a mass of abnormal cells (tumor). A definitive diagnosis of breast cancer is made when a sample of tissue is extracted or removed from the tumor (breast biopsy) and analyzed by a pathologist. The breast biopsy may be performed as a needle biopsy or a surgical biopsy. Most breast cancers begin in the cells lining the milk ducts or the lobules that produce milk. When the pathologist analyzes the breast biopsy sample from a cancer, one of the first steps is to determine whether the cancerous tissue is invasive, non-invasive or a combination of both patterns. Most breast cancers that have formed a lump are invasive tumors, which means the cancer cells have extended beyond the outer lining of the microscopic ductal structures where they began. Invasive ductal carcinoma is the most common of several types of breast cancer.

Ductal carcinoma in situ (DCIS) is a form of noninvasive breast cancer. When the pathologist describes DCIS in a report of breast tissue that has been analyzed microscopically, it means that he/she sees cancer cells that are located within ductal units, but the walls of those ductal units are intact. Most cases of DCIS require cancer-directed therapy (surgery and, possibly, radiation therapy) to remove and/or treat the abnormal breast tissue. Lobular carcinoma in situ (LCIS) is a condition in which abnormal cells are confined to the lobules (milk-secreting glands) of the breast. This pattern is a sign of overactive breast tissue that may be present throughout both breasts. Patients with LCIS are at increased risk for future breast cancer development and may be recommended for more extensive breast cancer screening or to consider breast cancer prevention options. When detected in the absence of invasive cancer, neither DCIS nor LCIS are life-threatening conditions because they are not biologically capable of metastatic spread to other organs of the body.

Invasive breast cancers that are caught early can usually be treated successfully with combinations of local, regional and systemic therapies. Local and regional therapies are typically in the form of radiation therapy and/or surgery, designed to eliminate the cancerous tissue in the breast and, if necessary, the underarm lymph nodes (glands). Systemic therapy is drug treatment designed to eliminate microscopic cancer cells that might be hiding in other organs of the body, such as the liver, lungs or bones. Microscopic cancer cells hiding in other organs are too small to be seen on imaging tests, such as CT or bone scans, and they do not cause symptoms.

Figure 1. Anatomy of the Breast

While screening tests such as mammograms, ultrasound and magnetic resonance imaging (MRI) are commonly used to detect breast changes, a biopsy is the only way to know if cancer is present. For a biopsy, a sample of the suspicious area, called a biopsy specimen, is taken and tested in the lab by a pathologist. If your biopsy results indicate cancer, staging is the next step.

Breast cancer is categorized by stages, depending on whether tumor cells have broken off from the tumor and traveled through the lymphatic system to lymph nodes (tiny, bean-shaped organs that are part of the immune system), or through the bloodstream to other parts of the body. Learn more about staging here.

Table 1. Types of breast cancer

Type Characteristics
Ductal carcinoma in situ (DCIS) Remains confined to the milk ductal units
Invasive (Infiltrating)
Cribriform Cancer cells that invade connective tissue and have “holes”
Ductal Cancer cells arise from the milk ducts but have spread beyond the ductal walls into surrounding breast tissue (fatty tissue, connective tissue, lymphatics and/or vascular structures within the breast)
Inflammatory Breast cancer that is associated with redness and swelling of the breast, often without a distinct lump
Lobular Cancer cells arise from the lobules but have spread beyond the lobules into surrounding breast tissue (fatty tissue, connective tissue, lymphatics, and/or vascular structures within the breast)
Medullary Soft, fleshy tumor, often associated with inflammatory cells (called lymphocytes); usually has a better prognosis when compared to invasive ductal or invasive lobular cancers of the same size
Metaplastic A rapidly growing tumor that contains a mixture of cell types, including epithelial (glandular) cells and mesenchymal (bone, skin and muscular) cells
Mucinous (colloid) Mucus is primary component of tumor; less likely to spread to lymph nodes
Papillary Tumor has small, finger-like projections; often occurs with DCIS
Tubular Small tumor, less likely to spread beyond breast
Receptor subtypes
Hormone receptor (ER or PR) positive and HER2-negative Tumor is positive for either ER or PR and negative for HER2
HER2-positive Tumor is positive for HER2 and includes any ER or PR status
Triple-negative Tumor is negative for ER and PR and does not overexpress HER2

New Ways of Defining Breast Cancer

Researchers have discovered that breast cancer tumors vary in several important ways. The identification of tumor markers, or biomarkers, and the development of technology for genetic profiling (studying several genes in a tumor simultaneously) have led to an additional classification of breast cancer according to subtypes based on molecular or genetic changes. This distinction is important because treatments and monitoring milestones, such as the length of time without progression and response to therapy, vary by subtype. Research advances continue to provide additional treatment options for various types of breast cancer (see Tumor Markers).

Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is diagnosed when tests performed on a breast biopsy and/or surgically-resected invasive breast cancer tissue reveal that the tumor is negative for the hormone receptors estrogen (ER) and progesterone (PR) as well as the human epidermal growth factor (HER2). The absence of these three biomarkers limits treatment options because therapies that target the hormone receptors and/or HER2 will not be effective. TNBC also tends to be more aggressive compared to non-TNBC and is more likely to have microscopic cancer cells hiding in other organs (micrometastases). Chemotherapy is, therefore, more likely to be recommended after surgery. Some TNBC patients may benefit from receiving chemotherapy before they have surgery to remove the tumor in the breast; this sequence is called neoadjuvant chemotherapy and will often shrink the tumor so that the patient can have a less-disfiguring lumpectomy to remove the cancer. Clinical trials may also be an option.

Talk with your doctor about genetic testing and counseling. Some breast cancers are caused by mutations in the BRCA1 and BRCA2 genes, which can be inherited. Genetic testing is recommended for patients diagnosed with TNBC under age 60, regardless of family history. Knowing whether you have one of these mutations may help genetic counselors and your medical team identify treatments that are more tailored to you.

Inflammatory Breast Cancer

Inflammatory breast cancer (IBC) occurs when cancer cells block the lymph vessels that drain the skin of the breast. This fluid may then become backed up, causing swelling in the breast and overlying skin. This disease is so-named because the breast may look red or inflamed or may feel warm. An identifying characteristic is that the breast skin may look pitted, resembling an orange peel.

IBC may be difficult to diagnose because people often report atypical symptoms. IBC may not form lumps like other breast cancers and may not show up on a mammogram. Often, it is misdiagnosed as mastitis (an infection of breast tissue), which can also cause swelling and tenderness in the breast.

Most cases of IBC are diagnosed as invasive ductal carcinomas because the cancer forms in the cells that line the milk ducts and spreads beyond the ducts. IBC skin symptoms typically progress quickly (sometimes in a matter of weeks or months). This cancer is always staged as either Stage III or IV disease. Your doctor may perform CT or PET to see if the cancer has spread to other organs. If metastases are identified, the patient is categorized as having Stage IV breast cancer. IBC is an aggressive cancer, and it is typically more challenging to treat than other types of breast cancer. Talk with your doctor about treatment options, including clinical trials.

Clinical trials are often recommended for people with IBC. Not only will patients have access to leading-edge treatments, they will be contributing to the research of this disease simply by participating. Ongoing research is investigating new treatment options or drug combinations. Talk with your doctor to see if a clinical trial is right for you.

Top Ten Things You Should Know About Breast Cancer

  1. No two breast cancers are exactly alike.

    As a result, the “best” treatment plan for each woman differs. The personalized approach to breast cancer treatment involves making decisions on the basis of many factors, including the type of cancer, the stage of disease, the results of biomarker testing, the genetic make-up of the tumor and a woman’s individual preferences.

  2. Breast cancer can be treated in a variety of settings.

    Cancer treatment centers may be freestanding facilities or they may be affiliated with a community hospital or an academic teaching hospital. Some cancer centers have been recognized by the National Cancer Institute (NCI) for their scientific excellence and extensive cancer-related resources. These centers are described as “NCI-designated cancer centers.” Centers accredited by the National Accreditation Program for Breast Centers (NAPBC) also offer benefits for women with breast cancer. See list of centers.

  3. It is acceptable to seek a second opinion.

    Getting a second opinion from another pathologist with extensive expertise in examining breast cancers can be of benefit, especially if there was difficulty or controversy in interpreting the initial findings. Getting a second opinion about the recommended treatment plan can also be of benefit. Many health insurance policies will cover a second opinion if you or your doctor requests it. The delay of getting a second opinion usually does not affect the outcome of treatment, but be sure to ask your doctor about this.

  4. Clinical trials offer benefits to many women with breast cancer.

    People who have participated in a clinical trial have identified several advantages, including having access to the best available care, playing an active role in their own health care, and making a valuable contribution to cancer research. Some risks may also be involved. Talk to your doctor or another member of your treatment team to learn more about clinical trials for which you may be eligible. Learn more about clinical trials.

  5. A team of health care professionals will be involved in your care.

    Because most women with breast cancer receive more than one type of treatment, care is planned and given by a team of health care specialists rather than just one physician. The treatment team usually involves a breast surgeon or surgical oncologist, radiation oncologist, medical oncologist, breast radiologist, pathologist, and a breast reconstructive surgeon. Additional health care professionals, such as nurses, physician assistants, nutritionists, social workers and others may also collaborate to provide optimal care. See Multipidisciplinary Team for more information.

  6. You should be an active participant in decision-making.

    Learn as much as you can about your particular type of cancer so that you can be fully informed and prepared to participate in the decision-making about treatment. Your doctors will discuss options, and family and friends may offer advice. But the “right” treatment decision is the one that’s best for you, based on your own perceptions of quality of life. Consider asking each of the doctors on your team about the benefits and side effects of their portion of therapy. See Treatment Option Charts.

  7. Side effects of treatment can be alleviated.

    Treatments for breast cancer may cause side effects, but there are now many ways to manage them. Talk to your doctor about the potential side effects of the treatment or treatments you’ve chosen and ask if there are ways to prevent or reduce these side effects. Be sure to tell your doctor or other members of your treatment team about symptoms you have so they can be managed promptly.

  8. Help is available for financial and practical issues.

    A variety of resources are available to help with expenses related to prescriptions, travel and health care equipment. Advocacy groups and community-based organizations often offer help with child care, provide transportation and even supply wigs. Ask social workers in your cancer center for information on local resources and be sure to review our list of resources for financial assistance.

  9. Support groups offer comfort and strength.

    Support groups provide an opportunity to talk with people who are facing some of the same challenges or have undergone similar treatments. Sharing your experience with others and hearing about their experiences can help reduce feelings of isolation. Many support groups are available online if you’d rather interact with others that way. Be sure to review our list of support groups.

  10. You can take control.

    A diagnosis of breast cancer is overwhelming, and it is easy to feel as if your life is out of control. But you have the power to overcome the challenges of breast cancer. Don’t be afraid to tell your doctors about your treatment preferences. Take good care of yourself by getting proper nutrition, exercise and sleep. Do whatever it takes to help you heal and feel physically and emotionally healthy, whether it be meditation, yoga, relaxation techniques, spirituality or counseling. Spend time with family and friends and be specific about what you need — and don’t need — from them. Enjoy your favorite activities. Live every day to its fullest.




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