Breast cancer is one of the most common types of cancer. Understanding your risks can help you receive proper screening for early detection.
Breast cancer 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.
There are currently 4 million women in the United States who have a history of breast cancer. It’s estimated that in 2024, there will be another
Male breast cancer is less common, but estimates suggest that about
Keep reading to learn 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, including ductal carcinoma in situ and lobular carcinoma in situ.
Ductal carcinoma in situ (DCIS)
DCIS refers to abnormal cells in milk ducts that haven’t spread. Some experts consider DCIS to be pre-cancerous, while others categorize it as noninvasive cancer.
There are several categories and grades of DCIS, which help doctors determine the likelihood of it becoming invasive breast cancer.
Read more about the different types of DCIS.
Lobular carcinoma in situ (LCIS)
LCIS is an uncommon condition characterized by abnormal cells in the milk glands. It’s not cancerous, but it can increase your risk of developing some types of breast cancer later on.
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. It makes up about 70% to 80% of breast cancers, according to the
Invasive ductal carcinoma occurs when cancer cells spread from your milk ducts into the surrounding breast tissue. If not caught early, it can potentially spread to other parts of your body through the lymphatic system.
Invasive lobular carcinoma
Invasive lobular carcinoma makes up about
Invasive lobular carcinoma tends to be harder to see on a mammogram or ultrasound than invasive ductal carcinoma. It occurs when cancer begins in the glands that produce milk and spreads to nearby tissue. It can also spread to distant body parts if not treated early.
About
Breast cancer by state
According to 2021 data from the Centers for Disease Control and Prevention (CDC), the states with the highest rates of breast cancer that year were:
| State | Number of new breast cancer cases per 100,000 females |
|---|---|
| Connecticut | 157.9 |
| District of Columbia | 147.2 |
| New Hampshire | 146.4 |
| Maine | 146.1 |
| North Carolina | 145.9 |
The states with the lowest breast cancer rates in 2021 were:
| State | Number of new breast cancer cases per 100,000 females |
|---|---|
| Nevada | 113.0 |
| Arizona | 113.8 |
| New Mexico | 119.4 |
| Vermont | 137.6 |
| South Alaska | 123.5 |
Breast cancer by race and ethnicity
This same 2021 report shows that breast cancer rates vary based on race and ethnicity in the United States:
| Race or ethnicity | Rates per 100,000 women per year |
|---|---|
| white, non-Hispanic | 139 |
| black, non-Hispanic | 132 |
| Hispanic | 106 |
| American Indian and Alaska Native, non-Hispanic | 117 |
| Asian and Pacific Islander, non-Hispanic | 114 |
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
Females have a much higher chance of developing breast cancer than males. Your chances of developing breast cancer also increase with age.
Approximately
Genetics
You may have a higher risk of breast cancer if you have certain genetic variants. Some of the genes that can increase breast cancer risk based on variants include:
- BRCA1
- BRCA2
- CDH1
- PALB2
Read more about genetic and hereditary risk factors for breast cancer.
Reproductive history
Starting menstruation before age 12 or menopause after age 55 is linked to an increased risk of developing breast cancer due to an increased amount of estrogen exposure.
Having your first child after the
This increased exposure comes from going through a higher number of menstrual cycles.
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.
Having dense breasts also appears
Read on about breast density and how it can impact breast cancer risk.
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 stopped 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
- having obesity or overweight after menopause
- frequent alcohol consumption
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 suggest you should visit a doctor for an exam:
- a lump in your breast or armpit
- swelling in your breast
- irritation or dimpling
- redness, other color changes, or flaking skin
- changes in the size or shape of your breast
- discharge from your nipple (other than breast milk)
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.
According to the
The ACS lists the 5-year relative survival rate as
They also note that Black women have the
Learn more about the disproportionate impact breast cancer has on Black women.
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 while others don’t, but certain risk factors are known to increase your chances, such as certain gene mutations, delayed menopause, and using hormonal birth control.
Detecting breast cancer in the early stages — before it spreads to other parts of your body — gives you the best outlook.