Breast cancer is a disease in which the cells within the breast grow uncontrollably and form a malignant tumor. The cancer tends to begin either in the cells of the lobules (milk-producing glands) or the pathways that drain milk from the lobules to the nipple (the ducts).

Breast cancer is the second-most common cancer in women after skin cancer. Note that men can also get breast cancer, although this happens in fewer than 1% of cases.

Breast Cancer Causes and Risk Factors

There is no single answer for what causes breast cancer. However, a variety of risk factors are associated with the disease.

While some breast cancer risk factors involve lifestyle choices and environmental circumstances, which are often considered to be controllable, others are based on a person’s genetic makeup and cannot be managed or altered.

Risk Factors of Breast Cancer
Age: As you age, your risk of breast cancer increases. Women age 55 and older are often found to have more invasive breast cancers.Genetics: Up to 10% of breast cancer diagnoses are considered hereditary, resulting from genetic mutations (such as BRCA1 or BRCA2) passed down from a parent.
Family History: While eight out of 10 women diagnosed with breast cancer have no family history of the disease, your risk nearly doubles if a first-degree relative (mother, daughter, sister) has/had it. If two first-degree relatives have/had it, your risk triples.Race and Ethnicity: In general, white women develop breast cancer more often than African-American women, but it is more common in African-American women under age 45. Asian, Hispanic, and Native American women have the lowest risk of being diagnosed and dying from the disease.
Weight: Since more fat tissue leads to higher estrogen levels, being overweight or obese can increase your risk of breast cancer, especially in postmenopausal women.Dense Breasts: Women with dense breasts are up to two times more likely to develop breast cancer than those with average breast density.
Early Menstruation: Women who started menstruating before the age of 12 have a slightly increased risk, likely due to longer exposure to estrogen and progesterone.Menopause after age 55: Similar to women who started menstruation early, those who go through menopause later also have an increased risk of developing breast cancer due to extended hormone exposure.
Alcohol Consumption: Studies show that your breast cancer risk increases with the amount of alcohol your drink. Women who drink two to five alcoholic beverages per day have a greater risk than non-drinkers.Tobacco: In addition to a myriad of other health complications, heavy smoking over a long time period is linked to a higher risk of breast cancer.
Late or no pregnancy: Women who had their first child after age 30 and those who never become pregnant have a slightly elevated breast cancer risk.Birth Control: Studies have found that women using oral contraceptives, injectable birth control, implants, IUDs, skin patches, and vaginal rings have a slightly higher risk than women who never used them.
Hormone Therapy: Studies also show that taking combined hormone replacement therapy for several years increases the risk of developing and dying from the disease.Chest Radiation: Women who have been treated with radiation therapy to the chest for another cancer have a significantly higher risk for breast cancer.
Night Work: Recent studies have suggested that women who work nights, such as doctors on a night shift, may have an increased risk of the disease, potentially due to changes in melatonin levels.Textured Breast Implants: At least one study by the FDA has shown that women who get a specific type of textured breast implant have a higher risk of developing breast cancer than other women.

Breast Cancer Symptoms

Unfortunately, in many cases there are no obvious signs or symptoms of breast cancer, which is why it is important to have regular screenings. Mammograms should be a normal part of an annual checkup for women who are 45 or older, although women who have a high risk of developing the disease may wish to be screened at an earlier age.

In some cases, an early sign of breast cancer may be a lump or mass in the breast. Cancerous lumps are often painless, hard, and may have uneven edges – although in some cases they can be rounded, soft, and tender. Also, the lump may not be on the breast itself, but may be nearby, such as under the arm.

Less Common Symptoms of Breast Cancer

  • Pain or swelling of the breast
  • Dimples or irritation on the skin
  • Thickening or redness of the nipple or skin of the breast
  • Pain or inward turning of the nipple
  • Discharge from the nipple (other than milk)

Some of these symptoms may indicate other health conditions or diseases, such as a cyst or some type of infection. If you experience any of the symptoms listed above, you should get them checked out by a doctor right away.

Learn About Other Cancers That Affect Women

Breast Cancer Diagnosis

The earlier breast cancer is detected and diagnosed, the better your chances are of fighting it. Whether it’s a lump you never felt before or visible changes in your skin, breast cancer symptoms can vary from person to person.

Your normal health care routine should include a weekly breast self-exam. If you notice any changes, you should schedule a doctor’s appointment immediately. Women over 40 and those with an increased risk of the disease are advised to have annual mammograms and physical exams.

Diagnostic Tests: If you’re experiencing breast cancer symptoms or the results of a screening test prove concerning, your doctor may run diagnostic tests, such as a biopsy, breast ultrasound, breast MRIs, or other breast imaging tests. Each test provides deeper insight into whether breast cancer is present and can help guide decisions on breast cancer treatment.

Monitoring Tests: If you are diagnosed with breast cancer, your doctor will use tests including bone scans, CT scans, MRIs, Ultrasounds, and PET scans to monitor your condition both during and after treatment. These tests will assess whether the therapies are working, whether the cancer has spread beyond the breast, and if there is a recurrence.

Because there are standard ways to detect breast cancer, a failure to diagnose the disease could be grounds for a legal action against a doctor who otherwise should have caught it. If you have been diagnosed with breast cancer and have never received a screening or diagnostic test, you may want to learn more about your legal rights.

Types of Breast Cancer

For the most part, breast cancer is a type of carcinoma (a cancer that begins in a skin tissue or the lining of an organ), and starts in the milk ducts or the lobules. Sarcomas, on the other hand, begin in the cells of fat, muscle, or connective tissue. In some rare cases, breast cancer can exist without the formation of a tumor or lump. It is also possible for a single breast tumor to be a combination of different breast cancer types.

Ductal Carcinoma In Situ (DCIS): As the most common non-invasive breast cancer, this starts inside the milk ducts and has yet to spread into normal surrounding breast tissue.

Invasive Ductal Carcinoma (IDC): The most common invasive breast cancer, IDC starts in a milk duct, breaks through the wall, and grows into the breast’s fatty tissue. Subtypes of invasive carcinoma  are named after the ways the cells are arranged:

  • Tubular Carcinoma of the Breast
  • Medullary Carcinoma of the Breast
  • Mucinous Carcinoma of the Breast
  • Papillary Carcinoma of the Breast
  • Cribriform Carcinoma of the Breast

Invasive Lobular Carcinoma (ILC): The second-most common form of breast cancer, this begins in the lobules and can spread to other parts of the body.

Inflammatory Breast Cancer: This rare invasive breast cancer accounts for up to 3% of all breast cancers. It causes the breast to become swollen and red, and develops rapidly.

Lobular Carcinoma In Situ (LCIS): Also known as lobular neoplasia, LCIS causes breast cells to look cancerous when no cancer is present. This abnormal cell growth increases your risk of developing invasive breast cancer later.

Paget’s Disease of the Nipple: Accounting for just 1% of all breast cancer cases, this rare cancer begins in the breast ducts and spreads to the nipple skin and areola.

Phyllodes Tumors of the Breast: These rare breast tumors form in the breast’s connective tissue and spread from there.

Breast Cancer Stages and Life Expectancy

Depending on how long the breast cancer has been present and how much it has spread, breast cancer diagnoses are given a stage, indicating the severity. Survival rates are significantly higher when breast cancer is diagnosed in its early stages.

Stage I: The breast cancer tumor is small and has either yet to spread to the lymph nodes, or only a miniscule area has spread in the sentinel lymph node.

Stage II: The breast cancer is larger than during stage I, and has spread to nearby lymph nodes.

Stage III: The tumor is larger still, and has spread into nearby tissue and lymph nodes in the underarm. It has not yet invaded distant parts of the body.

Stage IV: These metastatic cancers have spread not only beyond the breast and nearby lymph nodes, but to other parts of the body.

Breast Cancer Survival Rate

The overall 5-year survival rate for breast cancer patients is about 89.7%, according to the National Cancer Institute. However, survival rates and life expectancy among breast cancer patients vary significantly depending on the type of cancer and the stage at which it is diagnosed, as well as individual circumstances.

In general, survival rates are higher when treatment begins during the cancer’s early stages. For that reason, it is crucial to speak to your doctor immediately if you notice any signs or symptoms of breast cancer.

5-Year Survival Rates for Breast Cancer
Breast Cancer Stage5-Year Survival Rate
Stage INearly 100%
Stage II93%
Stage  III72%
Stage IV22%

Breast Cancer Prevention

There is no guaranteed way to prevent breast cancer. However, you can proactively limit your risk by following some of the best practices and preventative measures listed below.

Lifestyle Choices

Avoiding smoking, second-hand smoke inhalation, and frequent drinking may decrease your risk. Maintaining a healthy diet and weight are also recommended. In fact, a study by the Women’s Health Initiative found that a woman’s risk of developing breast cancer is reduced by 18% when she walks briskly for between 1.25 to 2.5 hours per week. To adhere to the American Cancer Society’s guidelines for adults, each week should include at least 150 minutes of moderate intensity activity or 75 minutes of vigorous exercise.

Pregnancy and Breastfeeding

Women who become pregnant at least once tend to have a lower rate of breast cancer than those who don’t. Breastfeeding is also linked to a lower risk of breast cancer.

Breast Cancer Screenings

Being screened regularly for breast cancer, especially if you are high-risk, can help to detect the disease earlier and prevent it from spreading. Starting at the age of 40, women may want to choose to get an annual mammogram, and women between the ages of 45 and 54 are encouraged to get annual screenings. Women age 55 and older may switch to getting breast cancer screenings every other year.

Healthy Diet

Studies show that a low-fat diet rich in a variety of fruits and vegetables may reduce the risk of breast cancer. For those women who have already had breast cancer, a similar diet may help to prevent a recurrence in the future.

Medications (Chemoprevention)

Some medications like tamoxifen and raloxifene – each of which may be used to treat breast cancer – can also work as a preventative measure in women who are at high risk of developing the disease. Multiple studies over the last 30 years have shown a decrease in breast cancer risk for women in high-risk groups, including at least one study that found the drug reduced the risk of several types of breast cancer (both invasive and non-invasive) by nearly 50% across a range of women in different age groups.

Surgery

Some women who have an elevated genetic risk for breast cancer may choose to have their breasts reduced using a procedure known as a preventative or prophylactic mastectomy. Another type of preventative surgery is to remove the ovaries, which will reduce the amount of estrogen in the body and thus reduce the risk of breast cancer.

Breast Cancer Treatments and Therapies

Breast cancer treatment depends largely on the type and stage of the cancer. It also takes into account the patient’s age, overall health, and personal preferences. Most people diagnosed with the disease will require some sort of surgery to remove the tumor, such as a lumpectomy (removing the tumor), mastectomy (removing one or both of the breasts), or the removal of lymph nodes from the underarm. A mastectomy is often the best option for patients with an advanced stage of cancer, a particularly large tumor, a history of previous treatment, or genetic disposition. After the mastectomy, many women choose to have reconstructive surgery to restore the appearance of the breast(s).

Surgery is rarely the sole treatment for breast cancer. Patients often require additional breast cancer treatment either before or after surgery, and sometimes both. This can include chemotherapy, radiation therapy, hormone therapy, and/or targeted drug therapies.

Chemotherapy

In patients with early-stage breast cancer, standard chemo regimens lower the risk of the cancer returning. In more advanced cases, chemo regimens may shrink or eliminate the cancer in 30-60% of patients.

Standard chemo regimens for breast cancer include:

  • AT: Adriamycin and Taxotere
  • AC ± T: Adriamycin and Cytoxan, with or without Taxol or Taxotere
  • CMF: Cytoxan, methotrexate, and
  • CEF: Cytoxan, Ellence, and fluorouracil
  • FAC: fluorouracil, Adriamycin, and Cytoxan
  • CAF: Cytoxan, Adriamycin, and fluorouracil
  • TAC: Taxotere, Adriamycin, and Cytoxan
  • GET: Gemzar, Ellence, and Taxol

Radiation

Also called radiotherapy, radiation is a highly targeted and effective way of destroying cancer cells that may persist in the breast after surgery.

Hormonal Therapy

These medicines treat hormone-receptor-positive breast cancers by lowering the amount of estrogen in the body and blocking its effect on breast cancer cells.

Targeted Therapies

Targeted breast cancer therapies focus on specific characteristics of cancer cells that are causing the cells to grow rapidly or abnormally. Many of these are immunotherapy drugs, which help kickstart or enhance the body’s natural immune system to fight the cancer.

There are currently eight drugs used for targeted breast cancer therapy:

  • Afinitor (everolimus)
  • Avastin (bevacizumab)
  • Herceptin (trastuzumab)
  • Ibrance (palbociclib)
  • Kadcyla (ado-trastuzumab emtansine)
  • Kisqali (ribociclib)
  • Parjeta (pertuzumab)
  • Tykerb (lapatinib)

Pregnant Women with Breast Cancer

For patients who are pregnant when diagnosed with breast cancer, treatment options become limited. While surgery and chemo are generally safe for both the mother and baby, other breast cancer treatments (such as targeted therapy, hormone therapy, and radiation therapy) may harm the baby and are not recommended during pregnancy.

While your regular screenings should help identify any signs of breast cancer, you should contact your doctor right away if you are experiencing breast cancer symptoms. The earlier you detect and diagnose the disease, the better your chances are of stopping its progression.