Breast Cancer

Medically Reviewed By William C. Lloyd III, MD, FACS
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What is breast cancer?

Breast cancer is a type of cancer that occurs when there is an uncontrolled growth of abnormal cells in the breast. Breast cancer can spread, or metastasize, to other parts of the body.

After skin cancer, breast cancer is the most common cancer affecting women in the United States. In 2018, more than 250,000 women were diagnosed with breast cancer. One in 8 American women will get breast cancer at some point during her lifetime. This translates to an average risk of about 12%.

Men can also develop breast cancer. Annually, about 2,500 men will face the diagnosis in the United States.

A family history of breast cancer and certain gene mutations increase the risk of developing breast cancer. BRCA1 and BRCA2 gene mutations can quadruple a woman’s risk of breast cancer, but only about 10% of breast cancers are linked to such mutations. Most breast cancers develop in women without a family history of it. Risk factors also include obesity, elevated alcohol use, and increased amounts of the hormone estrogen.

About 80% of breast cancer cases in women are invasive. This is breast cancer that has grown into nearby breast tissue or has spread to lymph nodes or other areas of the body. The remaining cases are non-invasive, or carcinoma in situ. This cancer has not spread anywhere and remains in its original area of the breast.

When doctors diagnose breast cancer in an early stage of growth, treatment is often successful and breast cancer survival rate is high. The prognosis for later stages of breast cancer is improving with ever more advanced and targeted treatments, but breast cancer screening with mammograms at age 40 and older is key to an early diagnosis and cure.

Prognosis of breast cancer depends on the type of breast cancer and the stage of advancement; your age, medical history, and coexisting conditions or diseases; and available treatments.

What are the different types of breast cancer?

There are several types of breast cancer including:

  • Ductal carcinoma in situ (DCIS), which develops and remains in the cells lining the milk ducts. About 20% of new cases are this very early and treatable type.
  • Invasive ductal carcinoma, which starts in the milk ducts and invades nearby breast tissue. This is the most common type.

  • Invasive lobular carcinoma, which starts in the glands that produce milk and invades nearby breast tissue. About 10% of breast cancers are this type.

Rarer types of breast cancer include inflammatory breast cancer, Paget’s disease of the nipple, phyllodes tumor, and angiosarcoma.

What are the symptoms of breast cancer?

The hallmark symptom of breast cancer is a breast lump, but many women do not detect a lump or experience symptoms in early stages of breast cancer.

A breast lump that is malignant is generally not painful, but pain can occur in some cases. There are a variety of causes of breast lumps, such as fibrocystic breasts or breast cysts. However, a doctor should evaluate any type of breast lump for possible breast cancer.

A malignant breast lump can occur by itself, or there may be other symptoms as well. Symptoms of breast cancer include:

  • Breast deformity or misshapen breast

  • Breast lump

  • Breast pain

  • Change in the look and feel of the skin of the breast, such as dimpling or puckering

  • Change in the size, shape or appearance of the breast

  • New onset of inverted nipple

  • Nipple discharge or tenderness

  • Rash or sore on the breast or nipple

  • Swelling of one arm

  • Weight loss

What are the stages of breast cancer?

The size of the cancerous tumor and how far it has spread determines the stage of breast cancer. Doctors use imaging procedures and breast biopsy results to assign a stage. The stages include:

  • Stage 0 is ductal carcinoma in situ (DCIS).

  • Stage I (1) is the earliest form of invasive breast cancer, less than 2 cm in diameter (less than 1 inch).

  • Stage II (2) is also an early form of invasive breast cancer, but the tumor is either larger than stage 1 or has spread to local lymph nodes.

  • Stage III (3) is locally advanced breast cancer that has spread to nearby tissues and lymph nodes.

  • Stage IV (4) is metastatic breast cancer that has spread to a distant body site(s). For breast cancer, common sites include the bones, lungs, brain, liver, and distant lymph nodes. 

What causes breast cancer?

The underlying cause of breast cancer is currently not known. However, it is believed that some cases of breast cancer are genetic and may be linked to certain defects of genes called BRCA1 and BRCA2.

Normally, cells in the breast that are old or damaged will stop reproducing and die. These cells are replaced by healthy young cells. Breast cancer occurs when old or damaged cells divide and multiply uncontrollably. This results in the development of a malignant mass of tissue (tumor) in the breast.

Without treatment, breast cancer cells can continue to multiply, spread to other parts of the body, and interfere with more of the body’s vital processes.

What are the risk factors for breast cancer?

There are many factors that are thought to increase your chances of developing cancer, including breast cancer. It’s important to remember that not all people with risk factors will develop breast cancer.

Risk factors for breast cancer include:

  • Beginning menstruation before age 12

  • Being older than 50 years of age. The rate of breast cancer is highest in women over the age of 70.

  • Caucasian race; however, in women under 45, breast cancer is more common in Black women than in women of other races.

  • Drinking more than 1 to 2 alcoholic drinks per day

  • Elevated estrogen levels in your body

  • Exposure to high doses of radiation, such as from radiation therapy in the chest area

  • Going through menopause after age 55

  • Having certain defects of BRCA1 and BRCA2 genes. Up to 10% of cancers are linked to genetic mutations. These mutations can quadruple a woman’s risk of the disease. Women also develop cancer earlier with these mutations.

  • Increased height

  • Never having children or having a first child after age 30

  • Obesity (after menopause)

  • Personal or family history of breast cancer. If a woman has a mother, sister or daughter with breast cancer, her risk of the disease nearly doubles. However, 85% of breast cancers occur in women with no family history of the disease. 

  • Taking drugs that contain the hormone estrogen

  • Having taken diethylstilbestrol (DES), a drug prescribed in the 1940s to 1960s to prevent miscarriage

How do you prevent breast cancer?

Most cases of breast cancer occur by chance. There is no single factor determining that risk. Still, you have control over some of the risk factors for breast cancer. You may be able to lower your risk of breast cancer by:

  • Eating a diet that is low in fat and salty and smoked foods, and high in fiber and fruits and vegetables
  • Maintaining a healthy weight
  • Not drinking alcohol or limiting alcohol intake to one drink per day for women and two drinks per day for men
  • If breast cancer runs in your family, considering genetic testing for breast cancer mutations and exploring prevention strategies, such as a prophylactic double mastectomy
  • If you decide to birth children, breastfeeding at least several months

Hormone replacement therapy and breast cancer risk

Taking a combination of estrogen and a progestin for postmenopausal symptoms is associated with a slightly increased risk of breast cancer, based on a large study conducted many years ago (Women’s Health Initiative). The longer a woman is on hormone replacement therapy (HRT), the higher the risk. HRT is also associated with greater breast density, which makes it harder to find signs of breast cancer on a mammogram.

Most providers advise only taking hormones if your menopause symptoms are affecting your quality of life, and to re-evaluate your needs every year. Talk with your Ob/gyn or primary healthcare provider about the benefits and risks of HRT based on your personal and family medical history.

Self-exam for breast cancer

In addition to yearly mammograms after age 40 and annual breast exams by your Ob/gyn or primary care provider, you can perform self-exams for breast cancer at home. While self-exams are not definitive in detecting breast cancer, they are an important tool in identifying changes in the breasts that may require further evaluation by your doctor.

At least once a month (after your period, if you are still menstruating), self-examine your breast with these steps:

  • Look at your breasts in the mirror to check for any visual changes, such as unusual color, shape or size; dimpling or puckering in the skin; newly inverted nipple; fluid or discharge from the nipple(s); or redness, rash or swelling. Do this first with your arms at your sides, then again with your arms raised.

  • While standing, raise one arm and use the opposite hand to examine the breast on the side with your raised arm. Use increasing degrees of pressure to feel around your breast, using a circular pattern to make sure you cover the full area, including under the armpit. Also check the area around the nipple and the nipple itself for any unusual discharge. Repeat for the other breast.

  • Lie down on a flat surface and repeat the manual exam of both breasts.

If you see or feel something unusual, make a prompt appointment to see your doctor for further evaluation. There are many reasons for breast changes, and many are not cancerous. However, the sooner you can receive an accurate diagnosis, the sooner you can begin treatment if needed.

What are the diet and nutrition tips for breast cancer?

The best breast cancer diet is one that helps you reach and maintain a healthy weight, as obesity is a significant risk factor for breast cancer and many other types of cancer. A healthy diet also helps lower your risk of other conditions, including diabetes and heart disease.

There are many studies on diet and breast cancer. Some research indicates that a diet high in fruits, vegetables, and dairy products, but low in red and processed meats, may lower the risk of breast cancer. Eating fresh, unprocessed food may also help you stay healthy as you undergo treatment for breast cancer.

A healthy diet includes:

  • Fish at least once a week

  • Fresh or frozen fruits and vegetables

  • Less red meat and fewer processed cold cuts

  • Less sugar, including sugary drinks

  • Little to no alcohol; no more than one drink per day for women and two drinks per day for men

Ask your healthcare provider for guidance before making significant changes to your diet. Many cancer treatment centers have dietitians on staff to help cancer patients with diet and nutrition. Consider working with this professional to enhance your existing diet or begin a more healthy lifestyle.

How do doctors diagnose breast cancer?

Mammogram screening finds most breast cancers in early stages. Often, this is before breast cancer symptoms, including a lump, even develop. Diagnostic imaging tests are necessary if a mammogram shows something suspicious or a woman finds a lump. However, the only way to know for sure if an area is cancerous is to biopsy the breast tissue in the area.

Breast tumor grading

Diagnosis includes staging and grading the tumor because the breast cancer stage and grade are critical in determining the prognosis and best treatment options. Pathologists grade the tumor by its appearance under the microscope (well or poorly differentiated cells) and by testing for the presence of specific receptors on the surface of the tumor cells.

Cell receptors are specialized proteins. The three main receptors on breast cancer tumor cells are estrogen receptors, progesterone receptors, and HER2 (human epidermal growth factor receptor 2). These receptors act as doorways for estrogen, progesterone, or human epidermal growth factor, respectively, to enter the cell. Once they enter the cell, they stimulate the cell to multiply. Tumors can have one, two or three types of receptors, or none of them.

Tumors with hormone receptors (for estrogen and/or progesterone) are hormone receptor-positive breast cancers. This is the case for most breast cancers. When HER2 is present, the cancer is HER2 positive. This is the case for about 20% of breast cancers. About 10% are positive for HER2 and one hormone receptor and a small number are positive for all three receptors.

When a tumor lacks all three receptors, it is triple-negative breast cancer. Among other factors, this makes the cancer cells more resistant to treatment. Up to 20% of breast cancers are this more aggressive form.

What are the treatments for breast cancer?

The goal of breast cancer treatment is to permanently cure the cancer or to bring about a complete remission of the disease. Remission means there is no longer any sign of the disease in the body, although it may recur or relapse later.

Breast cancer treatment plans are individualized for the type of breast cancer and stage of advancement; your age, medical history, and coexisting diseases or conditions; your personal preferences; and other factors.

Treatment options for breast cancer

Breast cancer treatment may include a combination of:

  • Chemotherapy drugs to kill actively growing cancer cells

  • Dietary counseling to help people with cancer maintain their strength and nutritional status

  • Hormone therapy drugs to block the effects of estrogen for certain types of breast cancer that are stimulated by estrogen

  • Immunotherapy drugs to stimulate the body’s ability to target and fight off cancer cells

  • Lumpectomy to remove a cancerous breast lump in early stage cancer while leaving the rest of the breast intact

  • Mastectomy to remove part or all of the affected breast, which may include removal of nearby lymph nodes and part of the chest muscles

  • Pain medications

  • Palliative cancer care to improve the overall quality of life for families and patients with serious diseases

  • Participation in a clinical trial to test promising new therapies and treatments for breast cancer

  • Physical therapy to help strengthen the body, increase alertness, reduce fatigue, and improve functional ability during and after cancer treatment

  • Radiation therapy to destroy cancer cells. Radiation therapy can also be useful to relieve symptoms of metastatic breast cancer tumors.

  • Targeted therapy drugs to kill specific types of breast cancer cells with less damage to healthy cells

Complementary treatments

Some complementary treatments can help people to better deal with breast cancer and its treatments. These treatments, sometimes referred to as alternative therapies, are used in conjunction with traditional medical treatments.

Complementary treatments are not meant to substitute for traditional medical care. Be sure to notify your doctor if you are taking nutritional supplements or homeopathic (nonprescription) remedies, as they may interact with the prescribed medical therapy.

Complementary treatments may include:

  • Acupuncture

  • Massage therapy

  • Nutritional dietary supplements, herbal remedies, tea beverages, and similar products

  • Yoga

Hospice care

In cases in which breast cancer has progressed to an advanced stage and is not responding to treatment, the goal of treatment shifts away from curing the disease. Hospice care helps people in their last phases of an incurable disease to live as fully and comfortably as possible. Hospice care involves medically controlling pain and other symptoms. Hospice nurses and volunteers provide psychological and spiritual guidance as well as services to assist the patient’s family.

How does breast cancer affect quality of life?

Nearly 4 million people in the United States are living with breast cancer. This includes people who have completed treatment and those still receiving it. With a fairly high survival rate, it is common for women to live decades without a recurrence. Still, it requires ongoing monitoring and, in some cases, lifelong treatment. Whether or not treatment is complete and successful, breast cancer can take a toll on life.

Health-related quality of life (HRQoL) describes how a disease affects a person’s overall well-being. It includes mental, physical and emotional health. It also includes social and sexual functioning and your ability to perform daily functions and roles. Non-health factors, such as finances, can play a role in HRQoL as well.

It’s not surprising that breast cancer can affect quality of life. During treatment, it can be difficult to deal with side effects and symptoms, such as fatigue. Mastectomy or other surgeries can have both physical and emotional impacts. Doctors and healthcare providers recognize this aspect of cancer treatment. Managing issues and worries that affect HRQoL is an important part of cancer care. And this continues after treatment as women transition to survivorship.

Breast cancer does not always have a negative effect on life. Some women report positive effects on spirituality, general outlook on life, and taking pleasure in daily moments. Researchers are exploring the benefits of exercise, social support, and mentoring others with the disease on long-term HRQoL in breast cancer survivors.

What are the potential complications of breast cancer?

Complications of breast cancer are caused by a rapid growth of abnormal cells. These cells can travel through the bloodstream and lymphatic system to other areas of the body, most often the bones, lungs and liver. There they can multiply rapidly and develop new malignant tumors that interfere with normal organ function.

Complications of breast cancer metastasis include:

You can best lower your risk of complications by following the treatment plan you and your healthcare team design specifically for you.

What is the survival rate and prognosis for breast cancer?

Doctors often talk about cancer survival as a 5-year survival rate. This rate shows how many people with the disease are still alive five years after diagnosis.

For breast cancer, a relative survival rate is a more common measure. It compares the survival of women with breast cancer to those in the general population. This rate shows how much the disease can shorten life. A relative survival rate of 80% means someone with the disease is 80% as likely as someone in the general population to be alive after five years.

The 5-year relative survival rates for breast cancer stages are as follows:

  • Stage 0 or I: 100%

  • Stage II: 93%

  • Stage III: 72%

  • Stage IV: 22%

For the most recent available data year (2018), 42,465 women died of breast cancer.

It’s important to remember that each cancer case—and person—is different. Statistics may also be based on older data and might not reflect current advances in therapies and treatments. Your doctor will discuss your individual prognosis in the context of your diagnosis, medical history, and available treatment options.

Breast cancer awareness

Breast cancer treatment has come a long way in the last 30 years. The incidence of breast cancer in the United States has been declining since the year 2000. The breast cancer death rate has been declining as well, especially in women younger than 50 years of age. There are more than 3.8 million U.S. breast cancer survivors.

October is Breast Cancer Awareness Month, marked by the color pink.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Sep 17
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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