An Essential Guide to Understanding Breast Cancer

Published September 7, 2023

Breast cancer is the 2nd most common cancer in women in the United States, accounting for around 30% of all new female cancers each year.¹

It’s estimated that there's a 1 in 8 chance of a woman developing breast cancer in her lifetime.

But this also means there’s a 7 in 8 chance that she won’t.¹

Understanding the complexities of breast cancer can be challenging. But with the right information, you can gain knowledge and take steps towards a healthy future. In this guide, you’ll find an overview of breast cancer, information on genetic risk factors, guidelines on screening recommendations, signs and symptoms to watch out for, and much more.

What is breast cancer?

Cancer starts when cells begin to grow out of control. Usually, cells grow and divide to form new cells as the body needs them. But when cells grow out of control, they can form a mass of tissue called a tumor. Breast cancer is a type of cancer that develops in one or both breasts. 

The breast is an organ made up of different tissues, including milk ducts, lobules (the glands that produce milk), blood vessels, lymph nodes, fat, connective tissue, skin, and the nipple. Breast cancer can start in any of these tissues. Breast cancer can also metastasize (pronounced muh-ta-stuh-size), which means that cancer cells can break away from the original tumor and travel to other parts of the body through the blood or lymph system.

What are the different types of breast cancer?

The type of cancer depends on where in the breast it started and other factors, like the location of the tumor and if the cancer cells have spread to other parts of the body.

When breast cancer cells have spread into the surrounding breast tissue, it’s called invasive. The 2 main types of invasive breast cancer are²:

1. Invasive ductal carcinoma (IDC) is an invasive breast cancer that starts in the milk ducts. It’s the most common form of breast cancer and about 80% of breast cancers are this type. 
2. Invasive lobular carcinoma (ILC) is an invasive breast cancer that starts in the lobules. It’s the second most common form of breast cancer and about 10% of all breast cancers are this type.

When breast cancer cells haven’t spread into the surrounding breast tissue, it’s called noninvasive or in situ. This means the cancer hasn’t spread beyond the area where it first developed. Noninvasive breast cancers are also called precancers because they have the potential to develop into invasive breast cancer. The 2 main types of noninvasive breast cancer are²:

1. Ductal carcinoma in situ (DCIS) is a noninvasive breast cancer that starts in the milk ducts. DCIS is considered a precancer, meaning that it has the potential to develop into invasive breast cancer. It also increases a person’s risk of developing an invasive breast cancer later in life. About 16% of breast cancer diagnoses are this type. 
2. Lobular carcinoma in situ (LCIS) is a noninvasive breast condition that starts in the lobules. LCIS doesn’t spread outside the lobules and isn’t considered a true breast cancer. But LCIS can increase a person’s risk of developing invasive breast cancer in the future.

Are there other types of invasive breast cancer?

Some invasive breast cancers have unusual features or grow in an abnormal way. These types are less common but can be more serious.

Inflammatory breast cancer (IBC) is a rare and aggressive type of invasive breast cancer. It accounts for about 1% to 5% of all breast cancers. IBC develops when cancer cells block the lymphatic vessels in the skin of the breast. The lymphatic vessels are a network of tiny tubes that carry lymph fluid throughout the body. When cancer cells block the lymphatic vessels, it causes the breast to become red, swollen, and warm. These symptoms can be mistaken for a breast infection. But unlike other types of breast cancer, IBC often doesn’t cause a breast lump. It sometimes isn’t detected on a mammogram, which can make it harder to diagnose.³

Triple-negative breast cancer (TNBC) is an aggressive type of invasive breast cancer. It accounts for about 10% to 15% of all breast cancers. TNBC differs from other types of invasive breast cancer because it tends to grow faster and has fewer treatment options. TNBC cells don’t have any of the 3 receptors that other breast cancers can have⁴:

1. Estrogen
2. Progesterone
3. Human epidermal growth factor (HER2)

TNBC cells test negative on all 3 tests, which is why it’s called triple-negative. Because these receptors are missing, TNBC can’t be treated with the same methods as other types of breast cancer. But recent medical breakthroughs have opened new treatment options.³

Are there any uncommon types of breast cancer?

While some breast cancers are more common, others are rarer and start to grow in other types of cells in the breast. Below are a few of the less common types that can require unique approaches to treatment:

Paget disease of the breast is a rare type of breast cancer. It accounts for about 1% to 3% of all breast cancers. It starts in the milk ducts and spreads to the nipple and area around the nipple (areola). Sometimes, it can be mistaken for skin conditions like eczema or psoriasis. Symptoms can include a red, scaly rash (with itching or burning) on or around the nipple.⁵

Angiosarcoma (pronounced an-jee-oh-sahr-koh-muh) is a rare type of breast cancer. It accounts for less than 1% of all breast cancers. Angiosarcoma starts in the blood vessels or lymph vessels in the breast. It can involve the breast tissue or the skin of the breast. Some angiosarcomas are caused by a complication of previous radiation therapy to the breast. It can happen 8 to 10 years after receiving radiation therapy. Symptoms can include skin changes on the breast (like purple bumps) or lumps in the breast.⁶

What are metastatic breast cancer and recurrent breast cancer?

Metastatic (pronounced meh-tuh-stat-ik) breast cancer is a type of breast cancer that has spread to other parts of the body, like the bones, brain, or lungs. It’s the most advanced stage of breast cancer. Metastatic breast cancer is often called stage IV breast cancer. But there are different ways to stage metastatic breast cancer, and the stage will depend on the location of the cancer and how much it’s spread.

Recurrent breast cancer is breast cancer that has come back after it’s been treated. Recurrent breast cancer can be local, regional, or distant:

• Local recurrence means that the cancer has come back in the same breast (chest) area as the original tumor
• Regional recurrence means that the cancer has come back in the lymph nodes in the underarm or in or around the collarbone
• Distant recurrence means that the cancer has spread away from the original tumor to other parts of the body (metastatic)

Can men get breast cancer?

Breast cancer is often thought of as a disease that only affects women. Although it’s most common in women, anyone with breast tissue can develop breast cancer—including men. About 1% of all breast cancer cases are diagnosed in men.⁷

In the United States in 2023, the American Cancer Society estimates that⁸:

• About 2,800 men will be diagnosed with invasive breast cancer
• About 530 men will die from breast cancer

Who’s most at risk for breast cancer?

The risk of breast cancer increases with age. Women over the age of 50 are at the highest risk for breast cancer. But breast cancer can occur at any age, even in women under the age of 40. Other factors that can increase the risk of breast cancer are⁹:

• Family history: Women who have a family history of breast cancer or ovarian cancer are at increased-risk for developing breast cancer. This is especially true if the family history includes a first-degree relative (mother, sister, or daughter) or multiple family members on either side of the family who have had breast or ovarian cancer. Having a first-degree male relative with breast cancer also raises a woman’s risk
• Personal health history: Women who have had breast cancer are more likely to get breast cancer a second time. Some noncancerous breast diseases are also linked to a higher risk of breast cancer
• Reproductive history: Women who start their period before the age of 12 and start menopause after age 55 are at increased risk for breast cancer
• Genetic mutations: Women who have certain genetic mutations, such as BRCA1 or BRCA2, are at an increased risk of breast, ovarian, and other cancers
• Dense breasts: Women who have dense breasts have a higher risk of breast cancer than people with less dense breasts. This is also because dense breasts are more difficult to see on mammograms, which can make it harder to detect tumors
• Radiation therapy: Women who had radiation therapy to the chest or breasts are at increased risk for breast cancer later in life

What are the BRCA1 and BRCA2 genes?

BRCA stands for "breast cancer gene." There are 2 BRCA genes:

1. BRCA1
2. BRCA2

Everyone has 2 copies of the BRCA1 and BRCA2 genes. One copy is inherited from each parent. These genes help to repair damaged DNA, keep cells healthy, and protect you from getting certain cancers. But when these genes are mutated, they can increase the risk of developing breast, ovarian, and other cancers. However, even if a person inherits a BRCA1 or BRCA2 mutation from one parent—they still have the normal copy of the BRCA1 or BRCA1 gene from the other parent.¹⁰

So, what happens when a second mutation occurs that affects the normal copy of the gene? The person no longer has a functional BRCA1 or BRCA2 gene. This means those genes can no longer protect the person as they were meant to.¹⁰

But just because a person inherits a BRCA1 or BRCA2 mutation doesn’t mean they will get breast cancer. Inherited gene mutations other than BRCA1 or BRCA2 can also cause breast cancer. Genetic testing can identify mutations by analyzing several genes at the same time using multigene panels.¹⁰

What are the signs and symptoms of breast cancer?

Not everyone has the same symptoms of breast cancer. Some people don't have any signs at all. But some of the signs to look for are¹²:

• A new lump or swelling in the breast or underarm
• A change in the texture of the breast (dimpling or puckering)
• Redness, scaling, or flaking of the skin on the breast or nipple
• A change in the color of the skin on the breast or nipple
• A change in the shape of the nipple
• Any unusual discharge from the nipple, including blood
• Pain in any area of the breast
• Any change in the shape or size of the breast
• Redness, warmth, and swelling of the breast

How is breast cancer diagnosed?

Breast cancer is diagnosed through a combination of tests and procedures, such as:

• Physical exams
• Lab tests
• Breast ultrasounds
• Mammograms
• Breast magnetic resonance imaging (MRI) 
• Biopsies

A biopsy is the only way to know for sure if a person has breast cancer. But other tests and procedures can be very helpful in identifying breast cancer. A breast biopsy is a procedure when a needle is used to remove cells from a suspicious area in the breast. The cells are then examined under a microscope to see if they are cancerous.

If breast cancer is diagnosed, other tests are performed to see if the cancer has spread. This process is called staging. Breast cancer is typically staged on a scale of 0 to IV.¹³ Stage 0 means that the cancer hasn't spread from its original location. Stage IV means that the cancer has spread to other parts of the body.

When is the right time to start breast cancer screening?

The right age, tests, and screening intervals depend on your risk of developing breast cancer. 

The American Cancer Society has guidelines with recommendations on how often women should get screened for breast cancer. These guidelines emphasize the importance of regular screenings for early detection and treatment. The guidance provided by the American Cancer Society helps women make informed decisions about their health and stay on top of their breast cancer screenings.

Guidelines for women at average-risk for breast cancer

A woman is considered to be at average-risk for breast cancer if she doesn’t have any of these risk factors¹⁴:

• A personal history of breast cancer
• A strong family history of breast cancer
• A genetic mutation known to increase the risk of breast cancer (such as BRCA1 or BRCA2)
• Chest radiation therapy before the age of 30

Breast cancer screening recommendations for women at average-risk¹⁴:

• Women ages 40 to 44 have the option to start yearly mammograms
• Women ages 45 to 54 should have yearly mammograms
• Women 55 and above can switch to mammograms every other year or continue yearly mammograms based on preference. Screenings should continue based on health

Guidelines for woman at high-risk for breast cancer

A woman is considered to be at high-risk for breast cancer if she has any of these risk factors¹⁴:

• A lifetime risk of breast cancer of about 20% to 25% (or greater), according to risk assessment tools 
• A known BRCA1 or BRCA2 gene mutation based on having genetic testing
• A first-degree relative (parent, brother, sister, or child) with a BRCA1 or BRCA2 gene mutation (and haven’t had genetic testing themselves)  
• Chest radiation therapy between the ages of 10 and 30
• Has Bannayan-Riley-Ruvalcaba syndrome, Cowden syndrome, or Li-Fraumeni syndrome, or (or has first-degree relatives who do)

Breast cancer screening recommendations for women at high-risk¹⁴:

• Women who are at high-risk for breast cancer should get a breast MRI and a mammogram every year, typically starting at age 30

No doctor visit is required to buy your own lab test at questhealth.com. PWNHealth and its affiliates review your purchase to ensure it is medically appropriate before submitting the test order for processing. PWNHealth also reviews your test results and will contact you directly if they require prompt attention. Included in each purchase is the option to discuss your test results with an independent physician; however, you are also encouraged to speak with your primary healthcare provider.

References

1. American Cancer Society. Key Statistics for Breast Cancer. Accessed August 11, 2023. https://www.cancer.org/cancer/types/breast-cancer/about/how-common-is-breast-cancer.html. 
2. Breastcancer.org. Types of Breast Cancer. Accessed August 11, 2023. https://www.breastcancer.org/types.
3. American Cancer Society. Inflammatory Breast Cancer. Accessed August 11, 2023. https://www.cancer.org/cancer/types/breast-cancer/about/types-of-breast-cancer/inflammatory-breast-cancer.html. 
4. American Cancer Society. Triple-negative Breast Cancer. Accessed August 11, 2023. https://www.cancer.org/cancer/types/breast-cancer/about/types-of-breast-cancer/triple-negative.html. 
5. American Cancer Society. About Breast Cancer. Accessed August 11, 2023. https://www.cancer.org/content/dam/CRC/PDF/Public/8577.00.pdf. 
6. American Cancer Society. Angiosarcoma of the Breast. Accessed August 11, 2023. https://www.cancer.org/cancer/types/breast-cancer/about/types-of-breast-cancer/angiosarcoma-of-the-breast.html.
7. Centers for Disease Control and Prevention. Breast Cancer in Men. Accessed August 11, 2023. https://www.cdc.gov/cancer/breast/men/index.htm. 
8. American Cancer Society. Key Statistics for Breast Cancer in Men. Accessed August 11, 2023. https://www.cancer.org/cancer/types/breast-cancer-in-men/about/key-statistics.html. 
9. Centers for Disease Control and Prevention. What Are the Risk Factors for Breast Cancer? Accessed August 11, 2023. https://www.cdc.gov/cancer/breast/basic_info/risk_factors. 
10. Centers for Disease Control and Prevention. The BRCA1 and BRCA2 Genes. Accessed August 11, 2023. https://www.cdc.gov/genomics/disease/breast_ovarian_cancer/genes_hboc.htm. 
11. Centers for Disease Control and Prevention. BRCA Gene Mutations. Accessed August 11, 2023. https://www.cdc.gov/cancer/breast/young_women/bringyourbrave/hereditary_breast_cancer/brca_gene_mutations.htm. 
12. Centers for Disease Control and Prevention. What Are the Symptoms of Breast Cancer? Accessed August 11, 2023. https://www.cdc.gov/cancer/breast/basic_info/symptoms.htm. 
13. Breastcancer.org. Breast Cancer Stages. Accessed August 11, 2023. https://www.breastcancer.org/pathology-report/breast-cancer-stages. 
14. American Cancer Society. American Cancer Society Early Detection of Brease Cancer. Accessed August 11, 2023. https://www.cancer.org/cancer/types/breast-cancer/screening-tests-and-early-detection/american-cancer-society-recommendations-for-the-early-detection-of-breast-cancer.html. 
15. American Cancer Society. Can Breast Cancer in Men Be Found Early? Accessed August 11, 2023. https://www.cancer.org/cancer/types/breast-cancer-in-men/detection-diagnosis-staging/detection.html.

Source

1. Centers for Disease Control and Prevention. Breast Cancer. Accessed August 11, 2023. https://www.cdc.gov/cancer/breast/index.htm.