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Breast cancer is the most common cancer in women in the
United States. According to the American Cancer Society, it's estimated
that About 178,480 women in the United States will be found to have
invasive breast cancer in 2007. About 40,460 women will die from the
disease this year. Right now there are slightly over 2 million women
living in the United States who have been treated for breast cancer.
If you're worried about developing breast cancer, or if
you know someone who has been diagnosed with the disease, one way to
deal with your concerns is to get as much information as possible.
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In this section you'll find important background
information about what breast cancer is and how it develops.
Breast cancer is a malignant tumor that grows in one or both of the
breasts. Breast cancer usually develops in the ducts or lobules, also
known as the milk-producing areas of the breast.
Breast cancer is the second leading cause of cancer death in women
(after lung cancer). Although African-American women have a slightly
lower incidence of breast cancer after age 40 than Caucasian women, they
have a slightly higher incidence rate of breast cancer before age 40.
However, African-American women are more likely to die from breast
cancer at every age. Breast cancer is much less common in males; by
comparison, the disease is about 100 times more common among women. The
American Cancer Society estimates that in 2007 some 2,030 new cases of
invasive breast cancer will be diagnosed among men in the United States.
Types of breast cancer
There are several different types of breast cancer that can be divided
into two main categories - noninvasive cancers and invasive cancers.
Noninvasive cancer may also be called "carcinoma in situ." Noninvasive
breast cancers are confined to the ducts or lobules and they do not
spread to surrounding tissues. The two types of noninvasive breast
cancers are ductal carcinoma in situ (referred to as
DCIS) and lobular carcinoma in situ (referred to as
LCIS).
It is known that hormones in a woman's body, such as estrogen and
progesterone, can play a role in the development of breast cancer. In
breast cancer, estrogen causes a doubling of cancer cells every 36
hours. The growing tumor needs to increase its blood supply to provide
food and oxygen. Progesterone seems to cause stromal cells (the woman's
own cells to send out signals for more blood supply to feed the tumor. (Source:
Dr. V. Craig Jordan, vice president and scientific director for the
medical science division at Fox Chase Cancer Center in Philadelphia as
quoted in NY Times, Hormones And Cancer: By Gina Kolata, Published:
December 26, 2006)
- Non-invasive breast cancer.
The majority of non-invasive breast cancers are DCIS. In DCIS, the
cancer cells are found only in the milk duct of the breast. If DCIS
is not treated, it may progress to invasive cancer.
In LCIS, the abnormal cells are found only in the lobules of the
breast. Unlike DCIS, LCIS is not considered to be a cancer. It is
more like a warning sign of increased risk of developing an invasive
breast cancer in the same or opposite breast. While LCIS is a risk
factor for invasive cancer, it doesn't actually develop into
invasive breast cancer in many women.
- Invasive breast cancer.
Invasive or infiltrating breast cancers penetrate through normal
breast tissue (such as the ducts and lobules) and invade surrounding
areas. They are more serious than noninvasive cancers because they
can spread to other parts of the body, such as the bones, liver,
lungs, and brain.
There are several kinds of invasive breast cancers.
The most common type is invasive ductal carcinoma, which
appears in the ducts and accounts for about 80 percent of all breast
cancer cases. There are differences in the various types of invasive
breast cancer, but the treatment options are similar for all of them.
Not all breast cancers are alike
Not all breast cancers are alike - there are different stages of breast
cancer based on the size of the tumor and whether the cancer has spread.
For doctor and patient, knowing the stage of breast cancer is the most
important factor in choosing among treatment options. Doctors use a
physical exam, biopsy, and other tests to determine breast cancer stage.
Stages of Breast Cancer
The most common system used to describe the stages of breast cancer is
the AJCC/TNM (American Joint Committee on Cancer/Tumor-Nodes-Metastases)
system. This system takes into account the tumor size and spread,
whether the cancer has spread to lymph nodes, and whether it has spread
to distant organs (metastasis).
All of this information is then combined in a process called stage
grouping. The stage is expressed as a Roman numeral. After stage 0
(carcinoma in situ), the other stages are I through IV (1-4). Some of
the stages are further sub-divided using the letters A, B, and C. In
general, the lower the number, the less the cancer has spread. A higher
number, such as stage IV (4), means a more advanced cancer.
These are the stages of breast cancer:
Stage 0 -
Stage 0 is carcinoma in situ, early stage cancer that is confined to
the ducts or the lobules, depending on where it started. It has not
gone into the tissues in the breast nor spread to other organs in
the body.
- Ductal carcinoma in situ (DCIS): This is
the most common type of noninvasive breast cancer, when
abnormal cells are in the lining of a duct. DCIS is also
called intraductal carcinoma. DCIS sometimes becomes
invasive cancer if not treated.
- Lobular carcinoma in situ (LCIS): This
condition begins in the milk-making glands but does not go
through the wall of the lobules. LCIS seldom becomes
invasive cancer; however, having LCIS in one breast
increases the risk of cancer for both breasts.
Stage I -
Stage I is an early stage of invasive breast cancer. In Stage I,
cancer cells have not spread beyond the breast and the tumor is no
more than 2 centimeters (three-quarters of an inch) across.
Stage II - Stage II is one of the following:
- The tumor in the breast is no more than 2
centimeters (three-quarters of an inch) across. The cancer
has spread to the lymph nodes under the arm.
- The tumor is between 2 and 5 centimeters
(three-quarters of an inch to 2 inches). The cancer may have
spread to the lymph nodes under the arm.
- The tumor is larger than 5 centimeters (2
inches). The cancer has not spread to the lymph nodes under
the arm.
Stage III -
Stage III may be a large tumor, but the cancer has not spread beyond
the breast and nearby lymph nodes. It is locally advanced cancer.
- Stage IIIA
- Stage IIIA is one of the following:
- The tumor
in the breast is smaller than 5 centimeters (2 inches).
The cancer has spread to underarm lymph nodes that are
attached to each other or to other structures.
- The tumor
is more than 5 centimeters across. The cancer has spread
to the underarm lymph nodes.
- Stage IIIB
- Stage IIIB is one of the following:
- The tumor
has grown into the chest wall or the skin of the breast.
- The cancer
has spread to lymph nodes behind the breastbone.
-
Inflammatory breast cancer [insert link to page on
inflammatory breast cancer] is a rare type of Stage IIIB
breast cancer. The breast looks red and swollen because
cancer cells block the lymph vessels in the skin of the
breast.
- Stage IIIC
- Stage IIIC is a tumor of any size. It has spread in one of
the following ways:
- The cancer
has spread to the lymph nodes behind the breastbone and
under the arm.
- The cancer
has spread to the lymph nodes under or above the
collarbone.
Stage IV -
Stage IV is distant metastatic cancer. The cancer has spread to
other parts of the body.
Recurrent cancer - Recurrent cancer is cancer that
has come back (recurred) after a period of time when it could not be
detected. It may recur locally in the breast or chest wall as
another primary cancer, or it may recur in any other part of the
body, such as the bone, liver, or lungs, which is generally referred
to as metastatic cancer.
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