What Is Breast Cancer?
Written by Penina Taylor
October is Breast Cancer Awareness Month, and there’s a lot to be aware of. While cancer is the second cause of death of women in the US, being beaten only by heart disease for women over the age of 19, according to the American Cancer Society, breast cancer is the second most common cancer among women after skin cancers. Breast cancer accounts for 30% of all new female cancers each year.
Cancer is a disease in which abnormal cells in the body grow uncontrollably and spread to other parts of the body. Cancer can start almost anywhere in the human body, which is made up of trillions of cells, but when it starts in the breast, it is called breast cancer. Although rare, men can also get breast cancer.
Survival rates today vs. years ago
The good news is that the survival rate for breast cancer continues to rise. The breast cancer 5-year survival rate – which is how all cancers are rated – is now between 90% and 98% (depending on if it was localized or not), whereas it was below 80% in 1950. That means that a woman today diagnosed with localized breast cancer has a 90-98% chance of being alive 5 years from now. This is significant as depending on age and other factors, the 5-year life expectancy of someone in the general population may be lower than that!
Are there different types of breast cancer?
When someone talks about breast cancer, they are not just talking about one disease. According to the National Breast Cancer Foundation, there are several types of breast cancer. Depending on which list you look at and how they separate them, there are at least 7 types of breast cancer. We will look at the 4 most common types.
Ductal Carcinoma In Situ (DCIS)
Approximately 20% of new breast cancer diagnoses will be ductal carcinoma in situ (DCIS). Nearly all women with this early stage of breast cancer can be cured.
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.
Although DCIS is in itself non-invasive, it 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.
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.
Invasive (infiltrating) ductal carcinoma (IDC)
This is the most common type of breast cancer. About 80% of invasive breast cancers are invasive (or infiltrating) ductal carcinomas (IDC).
IDC begins 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)
About 10% of invasive breast cancers are invasive lobular carcinomas (ILC).
ILC begins 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 20% of women with ILC might have cancer in both breasts at the time they are diagnosed.
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 (outcome).
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:
- IBC doesn’t look like a typical breast cancer. It often does not cause a breast lump, and it might not show up on a mammogram. This makes it harder to diagnose.
- IBC tends to occur in younger women (younger than 40 years of age).
- Black women appear to develop IBC more often than white women.
- IBC is more common among women who are overweight or obese.
- IBC tends to be more aggressive—it grows and spreads much more quickly—than more common types of breast cancer.
- IBC is always at a locally advanced stage when it’s first diagnosed because the breast cancer cells have grown into the skin. (This means it is at least stage III.)
- In about 1 of every 3 cases, IBC has already spread (metastasized) to distant parts of the body when it is diagnosed. This makes it harder to treat successfully.
- Women with IBC tend to have a worse prognosis (outcome) than women with other common types of breast cancer.
The good news is that the survival rate for breast cancer continues to rise.
What are the different stages of breast cancer?
When someone talks about being diagnosed with breast cancer, or any cancer for that matter, they often add the modifier of a stage. Stages describe whether or not the cancer has spread and if so, how far. It helps determine how serious the cancer is and how best to treat it. So what does it mean if someone has stage I cancer versus stage IV?
What stage the cancer is at is determined by examining tissue removed during an operation. The stages assigned to breast cancer are determined by a complex system of factors including: if there is an actual tumor (not all types of breast cancer have a tumor) and if so, its size and whether or not it has spread; how far it has spread (just lymph nodes, and how many, or also to other organs); does the cancer have the protein called an estrogen receptor? Does the cancer have the protein called a progesterone receptor?
Does the cancer make too much of a protein called HER2? How much do the cancer cells look like normal cells?
As you can see, explaining the stage of a particular case of breast cancer is quite complex, however, in general, stages of cancer can be broken down as follows:
Stage I: Cancer is localized to a small area and hasn’t spread to lymph nodes or other tissues.
Stage II: Cancer has grown, but it hasn’t spread.
Stage III: Cancer has grown larger and has possibly spread to lymph nodes or other tissues.
Stage IV: Cancer has spread to other organs or areas of the body. This stage is also referred to as metastatic or advanced cancer.
Though stages I through IV are the most common, there is also stage 0. This earliest phase describes cancer that is still localized to the area in which it started. Cancers that are still in stage 0 are usually easily treatable and are considered precancerous by most healthcare providers.
It is important to know that nearly 98% of cases of breast cancer are discovered not through mammograms but through self-exam – in other words, a woman discovers something unusual in her breasts by examining them herself. This is why it is important to do a self-exam on a regular basis. The earlier the abnormality is discovered, the higher the chances for a full recovery. Don’t leave it to chance; if you don’t already know how to do a breast self-exam, you can find detailed instructions on the National Breast Cancer Foundation’s website.
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