Breast cancer is the most common type of cancer diagnosed in women in the United States. It is also the leading cause of cancer mortality. Breast cancer can occur in both men and women, but it's more common in women. Early detection, prevention via genetic counseling, and a personalized approach to treatment have resulted in improved survival and lower deaths.
Below is a table that shows risk by age. Overall, for your entire lifetime, your risk is 1 in 8.
|If current age is...||Probability of breast cancer developing in next 10 years is:**||Or 1 in...|
|20||0.05% or < 1%||1985|
|30||0.44% or < 0.5%||2229|
|40||1.46% or < 1.5%||68|
|50||2.73% or < 2.8%||37|
|60||3.82% or < 3.9%||26|
|70||4.14% or <4.2%||24|
|Lifetime risk||12.22% or < 0.14%||7-8|
Table: Age-specific Probabilities of Developing Breast Cancer.
Most cases of breast cancer occur without symptoms, but there are some warning signs. These include changes in the appearance of skin overlying or nipples, presence of lumps, pain that can be localized or overall; constant or intermittent, itching, or staining of bras, shirts, or bed sheets.
Types of Breast Cancer
There are 8 kinds of breast cancer:
- Ductal carcinoma in situ (DCIS) is cancer in milk duct cells but is not considered invasive.
- Invasive Ductal carcinoma - cancer that forms in the duct cells.
- Inflammatory breast cancer - cancer cells block the lymphatic vessels in the skin covering the breast, causing the characteristic red, swollen appearance of the breast.
- Lobular carcinoma in situ (LCIS) - Lobular carcinoma in situ (LCIS) is an uncommon condition in which abnormal cells form in the milk glands (lobules) in the breast. LCIS isn't cancer.
- Invasive lobular carcinoma- milk-producing glands (lobules) become cancerous.
- Angiosarcoma - form in the lining of the blood and lymph vessels of the breast.
- Paget's disease of the breast - starts on the nipple and extends to the dark circle of skin (areola) around the nipple.
- Recurrent breast cancer - breast cancer that returns after initial therapy. If it is in another location, it is called metastatic.
Symptoms of Breast Cancer
Signs and symptoms of breast cancer may include:
- A breast lump or hardened area that feels different from the surrounding tissue
- Change in the size, shape, or appearance of a breast
- Changes to the skin over the breast, such as dimpling
- A recently inverted nipple
- Scaling, peeling, or crusting of the areola which is the pigmented area of skin surrounding the nipple or breast skin
- Redness or pitting (indented areas) of the skin over your breast, similar to the skin of an orange
- Retraction or pulling off a section of the tissue that makes a dent or depression
Breast cancer occurs when some breast cells begin to grow abnormally and faster until they form a lump or mass. Cells may spread (metastasize) through your breast to your lymph nodes or other parts of your body through blood vessels.
Researchers have identified hormonal, lifestyle, and environmental factors that may increase your risk of breast cancer such as smoking, alcohol, obesity, and radiation exposure. Women who take estrogen and progesterone postmenopausal have a slightly increased risk of developing breast cancer.
Besides family history, many women who develop breast cancer have no known risk factors other than simply being women.
Family history of breast cancer increases your risk of developing it and the increase in risk is even greater in families when it occurs premenopausal, bilateral, ovarian cancer, or where multiple generations are affected. It is estimated that between 5% and 10% of breast cancer result from inherited mutations.
The most well-known are breast cancer gene 1 (BRCA1) and breast cancer gene 2 (BRCA2), both of which significantly increase the risk of both breast and ovarian cancer. Both maternal and paternal family histories should be taken into account.
Genetic counseling is warranted if there is the BRCA1-2 and if there is a family history of other associated cancers such as thyroid, pancreatic, melanoma, gastric, ovarian sex cord tumors, colorectal, prostate (especially before age 55-60), endometrial, adrenocortical, childhood sarcoma, leukemia/lymphoma, and brain tumors.
Other factors that are associated with an increased risk of breast cancer include:
- Being a woman (100 times more likely than if you are a man).
- A personal history of breast conditions such as a breast biopsy that was found to be lobular carcinoma in situ (LCIS) or atypical hyperplasia of the breast.
- A personal history of breast cancer. If you've had breast cancer in one breast, you have an increased risk of having cancer in the other breast.
- Radiation exposure. If you received radiation treatments to your chest as a child or young adult, your risk of breast cancer is increased.
- Obesity. Being obese increases your risk of breast cancer.
- Beginning your period at a younger age. Beginning your period before age 12 increases your risk of breast cancer.
- Beginning menopause at an older age. If you began menopause at an older age, you're more likely to develop breast cancer.
- Having your first child at an older age. After age 30 may have an increased risk of breast cancer.
- Having never been pregnant. Women who have never been pregnant have a greater risk of breast cancer.
- Postmenopausal hormone therapy. Women who take hormone therapy such as estrogen and progesterone for menopause have an increased risk of breast cancer.
- Drinking alcohol. More than one drink a day is considered unhealthy for cancer risk and other diseases.
Making changes in your daily life may help reduce your risk of breast cancer. Breastfeeding and exercise decrease your risk of breast cancer. Other suggestions to lower risk are:
- Breast cancer screening with mammograms.
- Become familiar with your breasts through a breast self-exam for breast awareness.
- Drink alcohol in moderation, if at all.
- Exercise most days of the week. Aim for at least 30 minutes of exercise on most days of the week.
- Limit postmenopausal hormone therapy. To reduce the risk of breast cancer, use the lowest dose of hormone therapy possible for the shortest amount of time.
- Maintain a healthy weight. If your weight is healthy, work to maintain that weight.
- Choose a healthy diet. Women who eat a Mediterranean diet supplemented with extra-virgin olive oil and mixed nuts may have a reduced risk of breast cancer.
Diagnosing breast cancer
Tests and procedures used to diagnose breast cancer include:
Breast exam. You and your doctor will check both of your breasts and lymph nodes in your armpit, feeling for any lumps or other abnormalities. The following are causes for concern:
- New Lump or contour change
- Skin tethering or pulling
- Nipple inversion
- Dilated veins
- Sores or ulcerations
- Swelling or dimpling texture
- Fixed or immovable with respect to underlying tissue, skin, or muscle
- Mammogram. A mammogram is an X-ray of the breast but is less useful in dense breasts which account for 50% of breasts.
- Breast ultrasound. uses sound waves to produce images of structures deep within the body and can tell a fluid-filled mass (cyst) versus a solid mass. Cysts are benign and solid masses can be either benign or cancerous.
- Removing a sample of breast cells for testing (biopsy). A biopsy is the only definitive way to make a diagnosis of breast cancer. A specialized needle guided by X-ray extracts a piece of the issue.
- Breast magnetic resonance imaging (MRI). An MRI machine uses magnets and radio waves to create pictures of the interior of your breast. Before a breast MRI, you receive an injection of dye. No radiation is used.
Breast cancer stages range from 0 to IV with 0 indicating cancer that is noninvasive or contained within the milk ducts. Stage IV breast cancer, also called metastatic breast cancer, indicates cancer that has spread to other areas of the body.
Breast cancer staging also takes into account your cancer's grade, which is how abnormal the cells appear under a microscope; the presence of tumor markers, such as receptors for estrogen, progesterone, and HER2; and proliferation factors.
Most women undergo surgery for breast cancer and many also receive additional treatment after surgery, such as chemotherapy, hormone therapy, or radiation. Chemotherapy might also be used before surgery in certain situations.
Surveillance Epidemiology and End Results (SEER). Cancer Stat Facts: Female Breast Cancer. National Cancer Institute. Available at http://seer.cancer.gov/statfacts/html/breast.html#incidence-mortality.
Jatoi I, Anderson WF, Rosenberg PS. Qualitative age-interactions in breast cancer: a tale of two diseases? doi: 10.1097/COC.0b013e3181844d1c. Am J Clin Oncol. 2008 Oct. 31(5):504-6.
Pal T, Permuth-Wey J, Betts JA, Krischer JP, Fiorica J, Arango H, et al. BRCA1 and BRCA2 mutations account for a large proportion of ovarian carcinoma cases. Cancer. 2005 Dec 15. 104(12):2807-16.
Kelsey JL, Bernstein L. Epidemiology, and prevention of breast cancer. Annu Rev Public Health. 1996. 17:47-67.
Colditz GA, Rosner B. Cumulative risk of breast cancer to age 70 years according to risk factor status: data from the Nurses' Health Study. Am J Epidemiol. 2000 Nov 15. 152(10):950-64.
Cuzick J, DeCensi A, Arun B, Brown PH, Castiglione M, Dunn B, et al. Preventive therapy for breast cancer: a consensus statement. Lancet Oncol. 2011 May. 12(5):496-503.
Santen RJ, Boyd NF, Chlebowski RT, Cummings S, Cuzick J, Dowsett M, et al. Critical assessment of new risk factors for breast cancer: considerations for development of an improved risk prediction model. Endocr Relat Cancer. 2007 Jun. 14(2):169-87.
Speroff L. The Million Women Study and breast cancer. Maturitas. 2003 Sep 25. 46(1):1-6.