Breast cancer occurs almost entirely in women, but men can get breast cancer, too. It’s important to understand that most breast lumps are benign and not cancer (malignant). Non-cancer breast tumors are abnormal growths, but they do not spread outside of the breast. They are not life threatening, but some types of benign breast lumps can increase a woman's risk of getting breast cancer. Any breast lump or change needs to be checked by a health care professional to find out if it is benign or malignant (cancer) and if it might affect your future cancer risk.
Ductal Carcinoma In Situ (DCIS)
DCIS is also called intraductal carcinoma or stage 0 breast cancer. DCIS is a non-invasive or pre-invasive breast cancer. This means the cells that line the ducts have changed to cancer cells but they have not spread through the walls of the ducts into the nearby breast tissue.
Because DCIS hasn’t spread into the breast tissue around it, it can’t spread (metastasize) beyond the breast to other parts of the body.
However, DCIS can sometimes become an invasive cancer. At that time, the cancer has spread out of the duct into nearby tissue, and from there, it could metastasize to other parts of the body.
Right now, there’s no good way to know for sure which will become invasive cancer and which ones won’t, so almost all women with DCIS will be treated.
Invasive Breast Cancer (IDC/ILC)
Breast cancers that have spread into surrounding breast tissue are known as invasive breast cancers.
Most breast cancers are invasive, but there are different types of invasive breast cancer. The two most common are invasive ductal carcinoma and invasive lobular carcinoma.
Inflammatory breast cancer is also a type of invasive breast cancer.
Invasive (infiltrating) ductal carcinoma (IDC)This is the most common type of breast cancer. About 8 in 10 invasive breast cancers are invasive (or infiltrating) ductal carcinomas (IDC).
IDC starts in the cells that line a milk duct in the breast. From there, the cancer breaks through the wall of the duct, and grows into the nearby breast tissues. At this point, it may be able to spread (metastasize) to other parts of the body through the lymph system and bloodstream.
Invasive lobular carcinoma (ILC)
ILC starts in the breast glands that make milk (lobules). Like IDC, it can spread (metastasize) to other parts of the body. Invasive lobular carcinoma may be harder to detect on physical exam and imaging, like mammograms, than invasive ductal carcinoma. And compared to other kinds of invasive carcinoma, it is more likely to affect both breasts. About 1 in 5 women with ILC might have cancer in both breasts at the time they are diagnosed.
Less common types of invasive breast cancerThere are some special types of breast cancer that are sub-types of invasive carcinoma. They are less common than the breast cancers named above and each typically make up fewer than 5% of all breast cancers. These are often named after features of the cancer cells, like the ways the cells are arranged.
Some of these may have a better prognosis than the more common IDC. These include:
Triple-negative Breast Cancer
Triple-negative breast cancer (TNBC) accounts for about 10-15% of all breast cancers. The term triple-negative breast cancer refers to the fact that the cancer cells don’t have estrogen or progesterone receptors (ER or PR) and also don’t make any or too much of the protein called HER2. (The cells test "negative" on all 3 tests.) These cancers tend to be more common in women younger than age 40, who are Black, or who have a BRCA1 mutation.
TNBC differs from other types of invasive breast cancer in that it tends to grow and spread faster, has fewer treatment options, and tends to have a worse prognosis (outlook).
Triple-negative breast cancer can have the same signs and symptoms as other common types of breast cancer.
Once a breast cancer diagnosis has been made using imaging tests and a biopsy, the cancer cells will be checked for certain proteins. If the cells do not have estrogen or progesterone receptors (ER or PR), and also do not make any or too much of the HER2 protein, the cancer is considered to be triple-negative breast cancer.
Inflammatory Breast Cancer
Inflammatory breast cancer (IBC) is rare and accounts for only 1% to 5% of all breast cancers. Although it is a type of invasive ductal carcinoma, its symptoms, outlook, and treatment are different. IBC causes symptoms of breast inflammation like swelling and redness, which is caused by cancer cells blocking lymph vessels in the skin causing the breast to look "inflamed."
Inflammatory breast cancer (IBC) differs from other types of breast cancer in many ways:
Inflammatory breast cancer (IBC) can cause a number of signs and symptoms, most of which develop quickly (within 3 to 6 months), including:
If you have any of these symptoms, it does not mean that you have IBC, but you should see a doctor right away. Tenderness, redness, warmth, and itching are also common symptoms of a breast infection or inflammation, such as mastitis if you’re pregnant or breastfeeding. Because these problems are much more common than IBC, your doctor might suspect infection at first as a cause and treat you with antibiotics.
Treatment with antibiotics may be a good first step, but if your symptoms don’t get better in 7 to 10 days, more tests need to be done to look for cancer. Let your doctor know if it doesn't help, especially if the symptoms get worse or the affected area gets larger. The possibility of IBC should be considered more strongly if you have these symptoms and are not pregnant or breastfeeding, or have been through menopause. Ask to see a specialist (like a breast surgeon) if you’re concerned.
IBC grows and spreads quickly, so the cancer may have already spread to nearby lymph nodes by the time symptoms are noticed. This spread can cause swollen lymph nodes under your arm or above your collar bone. If the diagnosis is delayed, the cancer can spread to distant sites.
How is inflammatory breast cancer diagnosed?Imaging testsIf inflammatory breast cancer (IBC) is suspected, one or more of the following imaging tests may be done:
Angiosarcoma of the Breast
Angiosarcoma is a rare cancer that starts in the cells that line blood vessels or lymph vessels. Many times, it's a complication of previous radiation treatment to the breast. It can happen 8-10 years after getting radiation treatment to the breast.
Angiosarcoma can cause skin changes like purple-colored nodules and/or a lump in the breast. It can also occur in the affected arms of women with lymphedema, but this is not common. (Lymphedema is swelling that can develop after surgery or radiation therapy to treat breast cancer.)
One or more of the following imaging tests may be done to check for breast changes:biopsy, removing a small piece of the breast tissue and looking at it closely in the lab. Only a biopsy can tell for sure that it is cancer.
Paget Disease of the Breast
Paget disease of the breast is a rare type of breast cancer involving the skin of the nipple and the areola (the dark circle around the nipple). Paget disease usually affects only one breast. In 80-90% of cases, it’s usually found along with either ductal carcinoma in situ (DCIS) or infiltrating ductal carcinoma (invasive breast cancer).
The skin of the nipple and areola often looks crusted, scaly, and red. There may be blood or yellow fluid coming out of the nipple. Sometimes the nipple looks flat or inverted. It also might burn or itch. Your doctor might try to treat this as eczema first, and if it does not improve, recommend a biopsy.
Most people with Paget disease of the breast also have tumors in the same breast. One or more of the following imaging tests may be done to check for other breast changes:biopsy, removing a small piece of the breast tissue and looking at it closely in the lab. In some cases, the entire nipple may be removed. Only a biopsy can show for sure that it is cancer.
Phyllodes Tumors of the Breast
Phyllodes tumors (or phylloides tumors) are rare breast tumors that start in the connective (stromal) tissue of the breast, not the ducts or glands (which is where most breast cancers start). Most phyllodes tumors are benign and only a small number are malignant (cancer).
Phyllodes tumors are most common in women in their 40s, but women of any age can have them. Women with Li-Fraumeni syndrome (a rare, inherited genetic condition) have an increased risk for phyllodes tumors.
Phyllodes tumors are often divided into 3 groups, based on how they look under a microscope:
Phyllodes tumors are usually felt as a firm, painless breast lump, but some may hurt. They tend to grow large fairly quickly, and they often stretch the skin.
Sometimes these tumors are seen first on an imaging test (like an ultrasound or mammogram), in which case they’re often hard to tell apart from fibroadenomas.
The diagnosis can often be made with a core needle biopsy, but sometimes the entire tumor needs to be removed (during an excisional biopsy) to know for sure that it’s a phyllodes tumor, and whether it's malignant or not.
Breast cancers can start from different parts of the breast. Each breast is made up of glands, ducts, and fatty tissue. In women, the breast makes and delivers milk to feed newborns and infants. The amount of fatty tissue in the breast determines the size of each breast.
The breast has different parts: