Get the Facts—Breast Cancer Basics
Breast cancer is the most common cancer among American women (excluding skin
cancers).
But incidences of breast cancer have been decreasing since 1999, and deaths due
to breast cancer have been decreasing since 1990. Whether you've been diagnosed
with breast cancer, are a breast cancer survivor, or are caring for someone with
the disease, it's important to get the facts and to keep looking forward with hope.
What is breast cancer?
In breast cancer, certain cells in the breast grow uncontrollably, forming a
solid mass called a tumor.
The breast is an organ for making milk. To make a substance, the human body uses
glands. The female breast is mostly made up of glands called lobules that make milk,
as well as tiny tubes called ducts that carry milk from the lobules to the nipples.
Also in the breast is fatty tissue called stroma that surrounds the lobules, ducts,
blood vessels, and lymphatic vessels.
There are several different types of cancers that can form in the breast. Doctors
generally group the types together based on where in the breast they start, meaning
in what type of cells they're found. The main cells in the breast that can become
cancerous are those of the lobules and the ducts.
Hormones can affect breast cancer
Not all breast cancers are caused by excess hormones.
But, for some women, the key female hormones—estrogen and progesterone—promote the
growth of certain types of breast cancer cells.
Many types of breast cancer cells have what are called estrogen and/or progesterone
"receptors," or proteins on the outsides of the cells that can attach to hormones.
Women with receptor-positive cancers tend to have better treatment outcomes with
hormone therapy than those with non-hormone-related cancers.
What are the different types of breast cancer?
Most breast cancers start in either the ducts or the lobules.
So the two main types of breast cancer are called ductal carcinomas (cancers that
start in the ducts) and lobular carcinomas (cancers that start in the lobules).
Each of these types has further subtypes, such as carcinoma in situ and invasive
carcinoma.
Ductal carcinoma is the most common type of breast cancer.
Often an early form of breast cancer, this cancer begins in the cells that line
the breast's milk ducts. Here are the main types of ductal carcinoma:
- Ductal carcinoma in situ, or DCIS, is cancer that has not spread to other tissues
from the ducts
- The most common type of ductal carcinoma and the most common type of breast cancer
overall is invasive or infiltrating ductal carcinoma, or IDC. Nearly 8 out of 10
women with breast cancer have IDC. On mammograms, IDC lesions can appear star-like
or rounded in shape. This cancer can spread into the other parts of the breast tissue
and to other parts of the body
Lobular carcinoma is less common than ductal carcinoma.
This type of cancer begins in the cells of the breast's lobes, or lobules. Lobules
are glands that make milk. Here are some of the main types of lobular carcinoma:
- Lobular carcinoma in situ (LCIS) is found only in the lobules. This type of lobular
carcinoma does not spread to other tissues very often
- Invasive or Infiltrating lobular carcinoma, or ILC, accounts for about 5% of all
breast cancer diagnoses and often starts with a subtle thickening in the upper-outer
quadrant of the breast. Infiltrating lobular carcinomas often respond well to hormone
therapy. This cancer can spread to nearby breast tissues and other parts of the
body
Triple-negative breast cancer and medullary carcinoma are 2 other types that
affect some women.
Triple-negative breast cancer (TNBC) is distinguished by the fact that it doesn't
have the same hormone receptors that other types of breast cancer do. This aggressive
type of cancer makes up 15% of breast cancer diagnoses.
Triple-negative breast cancer often affects young women and African-American women.
And women under 40 years of age are slightly more than 1.5 times more likely to
develop triple-negative breast cancer.
Women with a mutation on a gene called BRCA1 are also more likely to develop triple-negative
breast cancer. This is especially true if they develop cancer before the age of
50.
Medullary carcinoma also, also accounts for about 15% of all breast cancer diagnoses.
Medullary carcinoma often occurs in women in their late 40s and 50s. Its cells tend
to resemble the gray matter (medulla) of the brain, hence the name for this type
of cancer.
There are several other, less common types of breast cancer.
These include a condition called Paget's disease of the nipple, inflammatory breast
cancer (IBC), male breast cancer, and several other types.
- Paget's disease is a rare condition in which cancer cells collect in the
nipple. This cancer can then spread from the ducts of the nipple to the
nipple's surface. The nipple and areola (the dark circle of skin around the nipple)
can then become red, itchy, and irritated. Paget's disease accounts for fewer than
5% of breast cancer cases in the US. But 97% of people with Paget's disease also
have another cancer somewhere else in the breast
- Inflammatory breast cancer (IBC) is very aggressive. This rare
type of breast cancer causes the lymph vessels in the skin of the breast to become
blocked. This cancer is called "inflammatory" because it often makes the breast
look swollen and red—"inflamed." IBC accounts for 1% to 5% of all breast cancer
cases in the United States. Inflammatory breast cancer tends to occur more often
in younger women, and African-American women appear to be at higher risk than white
women
- Men can develop breast cancer—but they're very unlikely to. Less
than 1% of all breast cancers occur in men. For the most part, men don't produce
a lot of female hormones, so they don't develop breast gland tissue. Sometimes,
however, men can have abnormal levels of certain hormones, or they may take certain
medicines that raise these levels. As a result, these men have increased amounts
of breast tissue and can develop breast cancer
These are just a few of the rare cancers of the breast.
Others exist, each accounting for a smaller percentage of overall breast cancer
diagnoses.
Types of breast cancer accounting for no more than 1% to 3% of total US breast cancer
diagnoses include tubular carcinoma (which has an excellent 10-year survival rate
of 95%), mucinous or colloid carcinoma, papillary carcinoma, and adenocystic carcinoma.
Find out more about breast cancer, how it's diagnosed and staged, and how it
can be treated.
Through CancerInformation.com, sanofi-aventis offers in-depth information on breast
cancer—from detection methods and risk factors to the various stages of the disease
and the ways it is treated. Get empowered through information.
Visit CancerInformation.com to find out more