Breast cancer is a type of cancer that usually forms in the ducts or lobules of the breast. Lobules are the glands that produce milk, and ducts are the tubes that transport milk to the nipples.
As of January 2021, over 3.8 million women in the United States have a history of breast cancer. It’s estimated that there will be another
Male breast cancer is less common, but about
In this article, we’ll highlight the most important facts you should know about breast cancer.
There are many types of breast cancer. Here are the most common forms.
In situ breast cancer
Breast cancer is classified as in situ when it’s contained to the milk ducts or glands and hasn’t spread to other breast tissue. Within this class, there are a few different types.
Ductal carcinoma in situ
Ductal carcinoma in situ is when cancer is limited to the ducts of your breasts. It makes up about
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Lobular carcinoma in situ
Lobular carcinoma in situ is an uncommon condition characterized by abnormal cells in the glands that produce milk. It’s considered a
It’s important to note that lobular carcinoma in situ often doesn’t show up on mammograms.
Invasive breast cancers
Invasive breast cancer occurs when cancer cells spread from the ducts and glands into your breast’s fat or connective tissue.
Invasive ductal carcinoma
Invasive ductal carcinoma is the most common type of breast cancer and makes up about
Invasive lobular carcinoma
Invasive lobular carcinoma makes up about
Invasive lobular carcinoma tends to be harder to detect than invasive ductal carcinoma. It occurs when cancer begins in the glands that produce milk and spread to nearby tissue. It also has the potential to spread to distant parts of your body if not treated early.
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It’s
According to data from the
Breast cancer by state
According to data from the Centers for Disease Control and Prevention (CDC), the states with the highest rates of breast cancer are:
| State | Age-adjusted rate per 100,000 women each year |
|---|---|
| District of Columbia | 145.9 |
| Hawaii | 144.3 |
| New Jersey | 138.4 |
| Minnesota | 138.3 |
| Montana | 137.5 |
The states with the lowest breast cancer rates are:
| State | Age-adjusted rate per 100,000 women each year |
|---|---|
| Wyoming | 107.6 |
| Arizona | 109.0 |
| Alaska | 111.2 |
| Utah | 112.4 |
| Texas | 112.6 |
Breast cancer by ethnicity
Breast cancer rates vary between
| Ethnicity | Rates per 100,000 women per year |
|---|---|
| Non-Hispanic white | 128.1 |
| African American | 124.3 |
| Hispanic/Latinx | 91.0 |
| Native American/Alaska Native | 91.9 |
| Asian American/Pacific Islander | 88.3 |
Researchers still don’t fully understand why breast cancer develops in some people but not others. However, a number of risk factors have been identified.
Sex and age
People assigned female sex at birth have a much higher chance of developing breast cancer than males. Your chances of developing breast cancer also increase with age.
In
Family history
Nearly
Reproductive factors
Starting menstruation before age 12 or menopause after age 55 is
Having your first pregnancy after age 30, never having a full-term pregnancy, and not breastfeeding are also linked to an increased risk of developing breast cancer.
Breast density
If you have an increased amount of glandular and connective tissue in your breasts, it can be more difficult to identify cancer cells in a mammogram. This increases the chances that breast cancer may go undetected.
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Exposure to estrogen
Using birth control pills is linked to an increased risk of developing breast cancer due to the increased exposure to estrogen. However, these hormones don’t increase your risk once you’ve stop using them for more than
Hormone replacement therapy is also thought to increase the risk of developing breast cancer in women.
Other factors
According to the
- lack of regular exercise
- being overweight or obese after menopause
- frequent alcohol consumption
and possibly:
- smoking
- exposure to cancer-causing chemicals
- working a night-shift job
Know the symptoms
Breast cancer symptoms vary between people, and some may not have any noticeable signs. Experiencing one of the following symptoms doesn’t necessarily mean you have breast cancer, but it does indicate that you should visit a doctor for an examination:
- lump in your breast or armpit
- pain or swelling in your breast
- irritation or dimpling
- redness or flaking skin
- changes in the size or shape of your breast
- discharge from your nipple (other than breast milk)
- pain around your nipple
Damage to the DNA of healthy cells can lead cancer cells to form. These cells rapidly divide and can develop into tumors. It’s still not clear why some people develop breast cancer while others do not. However, a combination of genetic and environmental factors are thought to play a role.
Genetic factors
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According to the National Cancer Institute, the 5-year relative survival rate for breast cancer in women is about
By stage, the 5-year relative survival rates are:
- Localized: 99.0 percent
- Regional: 85.8 percent
- Distant: 29.0 percent
The American Cancer Society lists the 5-year relative survival rate as
Survival rate by ethnicity
According to the CDC, the death rate per 100,000 cases is:
| Ethnicity | Deaths per 100,000 people |
|---|---|
| Non-Hispanic white | 19.4 |
| Black/African American | 26.9 |
| Native American/Alaska Native | 11.5 |
| Asian American /Pacific Islander | 11.9 |
| Hispanic/Latinx | 13.5 |
Black women have the
Other breast cancer facts
Here are some other facts to know about breast cancer:
- Aside from skin cancer, breast cancer is the
most common cancer in the United States. - Breast cancer is the second most common cause of cancer death in women behind lung cancer.
- The death rate of breast cancer declined by
39 percent between 1989 to 2015 in the United States. - Risk factors for the development of breast cancer in men include exposure to radiation, obesity, mutation in the genes BRCA 1 and 2, a family history of breast or ovarian cancer, Klinefelter syndrome, testicular disorders, diabetes, and gynecomastia.
Breast cancer is the second most common cause of female cancer death in the United States. Nearly 1 in 8 women will experience invasive breast cancer at some point in their life.
Researchers still don’t know why some people develop breast cancer and others don’t, but certain risk factors are known to increase your chances, such as certain gene mutations, delayed menopause, and use of hormonal birth control.