Breast cancer is the second most common cancer among women, and according to U.S. government estimates, 1 in 8 women will develop this disease in her lifetime, while 281,550 will be diagnosed in the U.S. during 2021.
On International Breast Cancer Awareness Day, according to the American Cancer Society, breast cancer is the most common cancer among American women.
Currently, the average U.S. woman's lifetime risk of developing breast cancer is about 13 percent. This means there is a 1 in 8 chance of getting it.
It is expected that this year about 49,290 new cases of infiltrating ductal carcinoma (the most common among breast cancers) will be diagnosed, while about 42,170 women will die from this disease.
In recent years, incidence rates have increased by 0.5 percent per year.
Currently, breast cancer is the second leading cause of cancer death in women, behind only lung cancer. A woman's chance of dying from breast cancer is about 1 in 39 - about 2.6 percent.
Since 2007, breast cancer death rates have remained stable in women under age 50, and have continued to decline in older women.
There are currently more than 3.8 million breast cancer survivors in the United States. This number includes women who are still in treatment and those who have completed treatment.
These declines are believed to be due to screening tests, better access to information, and improved treatments.
But what is breast cancer?
Breast cancer occurs when breast cells begin to grow out of control.
Breast cancer cells usually form a tumor that can often be seen on an x-ray or felt as a lump or mass. It occurs almost exclusively in women, but men can also get it.
It is important to know that most breast lumps are benign (not malignant or cancerous). Noncancerous or benign breast lumps are abnormal growths, but they do not spread outside the breast. These lumps are not life-threatening, although some types of benign lumps may increase the risk of malignancy.
Any lump or change in the breast should be examined by a doctor.
Where does breast cancer originate?
Cancers can start in different parts of the breast. Most begin in the ducts that carry milk to the nipple (ductal cancers), some begin in the glands that produce milk (lobular cancers), and there are other types that are less common, such as phyllodes tumor and angiosarcoma.
A small number of cancers begin in other breast tissues. These are called sarcomas and lymphomas and are not actually considered malignant.
How does it spread?
Breast cancer can spread when cancer cells reach the blood or lymph system and spread to other parts of the body.
The lymphatic system is a network of lymphatic vessels throughout the body that connects to the lymph nodes - small, bean-shaped clusters of immune system cells.
The clear fluid inside the lymph vessels, called lymph, contains tissue byproducts and waste material, as well as immune system cells. The lymph vessels carry lymph fluid out of the breasts. In the case of breast cancer, cancer cells can enter the lymph vessels and begin to grow in the lymph nodes.
Most of the lymphatic vessels in the breast drain into:
- Lymph nodes located under the arm (axillary nodes)
- Lymph nodes surrounding the collarbone (supraclavicular (above the collarbone) and infraclavicular (below the collarbone) lymph nodes)
- The lymph nodes inside the chest and near the breastbone (internal mammary lymph nodes).
If cancer cells have spread to your lymph nodes, there is a greater chance that the cells have moved through the lymphatic system and spread - metastasized - to other parts of the body.
The more lymph nodes there are with breast cancer cells, the greater the chance of finding cancer in other organs. Because of this, finding cancer in one or more lymph nodes often affects the treatment plan. Surgery to remove one or more lymph nodes is usually needed to find out if the cancer has spread.
However, not all women with cancer cells in their lymph nodes metastasize, and some women without cancer cells in their lymph nodes may develop metastases later in life.
Breast Cancer Risks and Prevention
While there is no absolute way to prevent breast cancer, there are steps you can take to reduce your risk.
A risk factor is anything that increases your chance of getting a disease. However, even if you have one or even many risk factors, it does not mean that you will necessarily get the disease.
The consumption of alcoholic beverages is clearly associated with an increased risk of breast cancer, and it increases with the amount consumed. Compared to women who do not drink alcohol, those who have 1 alcoholic drink a day have a small increase - about 7 to 10 percent - while women who have 2 to 3 drinks a day have about a 20 percent higher risk than those who do not drink alcohol.
The overweight or obesity after menopause is another risk factor. Before menopause, the ovaries make the most estrogen, and fat tissue makes only a small part of the total amount. After menopause (when the ovaries stop producing estrogen), most of a woman's estrogen comes from fat tissue. Too much fat tissue after menopause can raise estrogen levels and increase the chance of breast cancer.
The evidence linking physical activity to reduced breast cancer risk, especially in women who have gone through menopause, is growing. All that remains to be determined is how much activity is necessary. Some studies have found that even just a couple of hours a week may be beneficial, although more activity seems to be better.
Women who have not had children or those who had their first child after age 30 generally have a slightly higher risk.
Most studies suggest that breastfeeding may slightly decrease the risk of breast cancer, especially if it lasts for 1 year or longer. But this has been very difficult to study, especially in places like the United States, where breastfeeding for such a long period of time is not common.
If you are a woman at increased risk for breast cancer - for example, because of a significant family history, a known genetic mutation that increases breast cancer risk, such as in the BRCA1 or BRCA2 gene, or if you have had ductal carcinoma in situ or lobular carcinoma in situ - there are some helpful steps to reduce your chances of getting breast cancer or to help find it early:
- Genetic Counseling and Testing for Breast Cancer Risk
- Careful observation for early signs
- Medications to reduce risk
- Preventive (prophylactic) surgery
Your doctor can help determine your risk for breast cancer, and can tell you if any of these options may be appropriate.
This year marks the 30th anniversary of the National Breast and Cervical Cancer Early Detection Program, which provides free breast and cervical cancer screenings to low-income, uninsured and underinsured women in every state, as well as many organizations and territories.
For information on how to get screened through this program, you can visit the site https://www.cdc.gov/cancer/nbccedp/screenings.htm. For more information on breast cancer you can visit www.cancer.gov/breast. National Cancer Institute information specialists are also available to help answer disease-related questions in English and Spanish at 1-800-422-6237.
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