Breast Cancer Statistic

 About 1 in 8 women in the United States (between 12 and 13%) will develop invasive breast
cancer over the course of her lifetime.
 women In 2010, an estimated 207,090 new cases of invasive breast cancer are expected to be
diagnosed in women in the U.S., along with 54,010 new cases of non-invasive (in situ) breast
cancer.
 About 1,970 new cases of invasive breast cancer will be diagnosed in men in 2010. Less than 1%
of all new breast cancer cases occur in men.
 From 1999 to 2006, breast cancer incidence rates in the U.S. decreased by about 2% per year.
One theory is that this decrease was partially due to the reduced use of hormone replacement
therapy (HRT) by women after the results of a large study called the Women’s Health Initiative
were published in 2002. These results suggested a connection between HRT and increased
breast cancer risk.
 About 39,840 women in the U.S. are expected to die in 2010 from breast cancer, though death
rates have been decreasing since 1991. These decreases are thought to be the result of
treatment advances, earlier detection through screening, and increased awareness.
 For women in the U.S., breast cancer death rates are higher than those for any other cancer,
besides lung cancer.
 Besides skin cancer, breast cancer is the most commonly diagnosed cancer among U.S. women.
More than 1 in 4 cancers in women (about 28%) are breast cancer.
 Compared to African American, white women are slightly more likely to develop breast cancer,
but less likely to die of it. One possible reason is that African American women tend to have
more aggressive tumors, although why this is the case is not known. Women of other ethnic
backgrounds — Asian, Hispanic, and Native American — have a lower risk of developing and
dying from breast cancer than white women and African American women.
 In 2010, there are more than 2.5 million breast cancer survivors in the U.S.
 A woman’s risk of breast cancer approximately doubles if she has a first-degree relative (mother,
sister, daughter) who has been diagnosed with breast cancer. About 20-30% of women
diagnosed with breast cancer have a family history of breast cancer.
 About 5-10% of breast cancers can be linked to gene mutations (abnormal changes) inherited
from one’s mother or father. Mutations of the BRCA1 and BRCA2 genes are the most common.
Women with these mutations have up to an 80% risk of developing breast cancer during their
lifetime, and they are more likely to be diagnosed at a younger age (before menopause). An
increased ovarian cancer risk is also associated with these genetic mutations. In men, about 1 in
10 breast cancers are believed to be due to BRCA2 mutations and even fewer cases to BRCA1
mutations.
 About 70-80% of breast cancers occur in women who have no family history of breast cancer.
These occur due to genetic abnormalities that happen as a result of the aging process and life in
general, rather than inherited mutations.
 The most significant risk factors for breast cancer are gender (being a woman) and age (growing
older).
Breast Cancer Risk Factors

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Page last modified on: November 25, 2008

A “risk factor” is anything that increases your risk of developing breast cancer. Many of the most
important risk factors for breast cancer are beyond your control, such as age, family history, and
medical history. However, there are some risk factors you can control, such as weight, physical
activity, and alcohol consumption.

Be sure to talk with your doctor about all of your possible risk factors for breast cancer. There
may be steps you can take to lower your risk of breast cancer, and your doctor can help you
come up with a plan. Your doctor also needs to be aware of any other risk factors beyond your
control, so that he or she has an accurate understanding of your level of breast cancer risk. This
can influence recommendations about breast cancer screening — what tests to have and when to
start having them.

Risk factors you can control

Weight. Being overweight is associated with increased risk of breast cancer, especially for
women after menopause. Fat tissue is the body’s main source of estrogen after menopause, when
the ovaries stop producing the hormone. Having more fat tissue means having higher estrogen
levels, which can increase breast cancer risk.

Diet. Diet is a suspected risk factor for many types of cancer, including breast cancer, but studies
have yet to show for sure which types of foods increase risk. It’s a good idea to restrict sources
of red meat and other animal fats (including dairy fat in cheese, milk, and ice cream), because
they may contain hormones, other growth factors, antibiotics, and pesticides. Some researchers
believe that eating too much cholesterol and other fats are risk factors for cancer, and studies
show that eating a lot of red and/or processed meats is associated with a higher risk of breast
cancer. A low-fat diet rich in fruits and vegetables is generally recommended. For more
information, visit our page on healthy eating to reduce cancer risk in the Nutrition section.

Exercise. Evidence is growing that exercise can reduce breast cancer risk. The American Cancer
Society recommends engaging in 45-60 minutes of physical exercise 5 or more days a week.

Alcohol consumption. Studies have shown that breast cancer risk increases with the amount of
alcohol a woman drinks. Alcohol can limit your liver’s ability to control blood levels of the
hormone estrogen, which in turn can increase risk.

Smoking. Smoking is associated with a small increase in breast cancer risk.

Exposure to estrogen. Because the female hormone estrogen stimulates breast cell growth,
exposure to estrogen over long periods of time, without any breaks, can increase the risk of
breast cancer. Some of these risk factors are under your control, such as:

 taking combined hormone replacement therapy (estrogen and progesterone; HRT) for several
years or more, or taking estrogen alone for more than 10 years
 being overweight
 regularly drinking alcohol

Recent oral contraceptive use. Using oral contraceptives (birth control pills) appears to slightly
increase a woman’s risk for breast cancer, but only for a limited period of time. Women who
stopped using oral contraceptives more than 10 years ago do not appear to have any increased
breast cancer risk.

Stress and anxiety. There is no clear proof that stress and anxiety can increase breast cancer
risk. However, anything you can do to reduce your stress and to enhance your comfort, joy, and
satisfaction can have a major effect on your quality of life. So-called “mindful measures” (such
as meditation, yoga, visualization exercises, and prayer) may be valuable additions to your daily
or weekly routine. Some research suggests that these practices can strengthen the immune
system.

Risk factors you can’t control

Gender. Being a woman is the most significant risk factor for developing breast cancer.
Although men can get breast cancer, too, women’s breast cells are constantly changing and
growing, mainly due to the activity of the female hormones estrogen and progesterone. This
activity puts them at much greater risk for breast cancer.

Age. Simply growing older is the second biggest risk factor for breast cancer. From age 30 to 39,
the risk is 1 in 233, or .43%. That jumps to 1 in 27, or almost 4%, by the time you are in your
60s.

Family history of breast cancer. If you have a first-degree relative (mother, daughter, sister)
who has had breast cancer, or you have multiple relatives affected by breast or ovarian cancer
(especially before they turned age 50), you could be at higher risk of getting breast cancer.

Personal history of breast cancer. If you have already been diagnosed with breast cancer, your
risk of developing it again, either in the same breast or the other breast, is higher than if you
never had the disease.

Race. White women are slightly more likely to develop breast cancer than are African American
women. Asian, Hispanic, and Native American women have a lower risk of developing and
dying from breast cancer.

Radiation therapy to the chest. Having radiation therapy to the chest area as a child or young
adult as treatment for another cancer significantly increases breast cancer risk. The increase in
risk seems to be highest if the radiation was given while the breasts were still developing (during
the teen years).

Breast cellular changes. Unusual changes in breast cells found during a breast biopsy (removal
of suspicious tissue for examination under a microscope) can be a risk factor for developing
breast cancer. These changes include overgrowth of cells (called hyperplasia) or abnormal
(atypical) appearance.

Exposure to estrogen. Because the female hormone estrogen stimulates breast cell growth,
exposure to estrogen over long periods of time, without any breaks, can increase the risk of
breast cancer. Some of these risk factors are not under your control, such as:

 starting menstruation (monthly periods) at a young age (before age 12)

 going through menopause (end of monthly cycles) at a late age (after 55)
 exposure to estrogens in the environment (such as hormones in meat or pesticides such as DDT,
which produce estrogen-like substances when broken down by the body)

Pregnancy and breastfeeding. Pregnancy and breastfeeding reduce the overall number of
menstrual cycles in a woman’s lifetime, and this appears to reduce future breast cancer risk.
Women who have never had a full-term pregnancy, or had their first full-term pregnancy after
age 30, have an increased risk of breast cancer. For women who do have children, breastfeeding
may slightly lower their breast cancer risk, especially if they continue breastfeeding for 1 1/2 to 2
years. For many women, however, breastfeeding for this long is neither possible nor practical.

DES exposure. Women who took a medication called diethylstilbestrol (DES), used to prevent
miscarriage from the 1940s through the 1960s, have a slightly increased risk of breast cancer.
Women whose mothers took DES during pregnancy may have a higher risk of breast cancer as
well.

Breast cancer is an uncontrolled growth of breast cells. To better understand breast cancer, it
helps to understand how any cancer can develop.

Cancer occurs as a result of mutations, or abnormal changes, in the genes responsible for
regulating the growth of cells and keeping them healthy. The genes are in each cell’s nucleus,
which acts as the “control room” of each cell. Normally, the cells in our bodies replace
themselves through an orderly process of cell growth: healthy new cells take over as old ones die
out. But over time, mutations can “turn on” certain genes and “turn off” others in a cell. That
changed cell gains the ability to keep dividing without control or order, producing more cells just
like it and forming a tumor.

A tumor can be benign (not dangerous to health) or malignant (has the potential to be
dangerous). Benign tumors are not considered cancerous: their cells are close to normal in
appearance, they grow slowly, and they do not invade nearby tissues or spread to other parts of
the body. Malignant tumors are cancerous. Left unchecked, malignant cells eventually can
spread beyond the original tumor to other parts of the body.

The term “breast cancer” refers to a malignant tumor that has developed from cells in the
breast. Usually breast cancer either begins in the cells of the lobules, which are the milk-
producing glands, or the ducts, the passages that drain milk from the lobules to the nipple. Less
commonly, breast cancer can begin in the stromal tissues, which include the fatty and fibrous
connective tissues of the breast.

Breast Anatomy

 Larger Version

Over time, cancer cells can invade nearby healthy breast tissue and make their way into the
underarm lymph nodes, small organs that filter out foreign substances in the body. If cancer cells
get into the lymph nodes, they then have a pathway into other parts of the body. The breast
cancer’s stage refers to how far the cancer cells have spread beyond the original tumor (see
Stages of Breast Cancer table for more information).

Breast cancer is always caused by a genetic abnormality (a “mistake” in the genetic material).
However, only 5-10% of cancers are due to an abnormality inherited from your mother or father.
About 90% of breast cancers are due to genetic abnormalities that happen as a result of the aging
process and the “wear and tear” of life in general.

While there are steps every person can take to help the body stay as healthy as possible (such as
eating a balanced diet, not smoking, limiting alcohol, and exercising regularly), breast cancer is
never anyone's fault. Feeling guilty, or telling yourself that breast cancer happened because of
something you or anyone else did, is not productive.

Stages of Breast
  Larger Version

Cancer stage is based on the size of the tumor, whether the cancer is invasive or non-invasive,
whether lymph nodes are involved, and whether the cancer has spread beyond the breast.

The purpose of the staging system is to help organize the different factors and some of the
personality features of the cancer into categories, in order to:

 best understand your prognosis (the most likely outcome of the disease)
 guide treatment decisions (together with other parts of your pathology report), since clinical
studies of breast cancer treatments that you and your doctor will consider are partly organized
by the staging system
 provide a common way to describe the extent of breast cancer for doctors and nurses all over
the world, so that results of your treatment can be compared and understood

Stage 0
Stage 0 is used to describe non-invasive breast cancers, such as DCIS and LCIS. In stage 0, there
is no evidence of cancer cells or non-cancerous abnormal cells breaking out of the part of the
breast in which they started, or of getting through to or invading neighboring normal tissue.

Stage I
Stage I describes invasive breast cancer (cancer cells are breaking through to or invading
neighboring normal tissue) in which:

 the tumor measures up to 2 centimeters, AND

 no lymph nodes are involved
Stage II
Stage II is divided into subcategories known as IIA and IIB.

Stage IIA describes invasive breast cancer in which:

 no tumor can be found in the breast, but cancer cells are found in the axillary lymph nodes (the
lymph nodes under the arm), OR
 the tumor measures 2 centimeters or less and has spread to the axillary lymph nodes, OR
 the tumor is larger than 2 centimeters but not larger than 5 centimeters and has not spread to
the axillary lymph nodes

Stage IIB describes invasive breast cancer in which:

 the tumor is larger than 2 but no larger than 5 centimeters and has spread to the axillary lymph
nodes, OR
 the tumor is larger than 5 centimeters but has not spread to the axillary lymph nodes

Stage III
Stage III is divided into subcategories known as IIIA, IIIB, and IIIC.

Stage IIIA describes invasive breast cancer in which either:

 no tumor is found in the breast. Cancer is found in axillary lymph nodes that are clumped
together or sticking to other structures, or cancer may have spread to lymph nodes near the
breastbone, OR
 the tumor is 5 centimeters or smaller and has spread to axillary lymph nodes that are clumped
together or sticking to other structures, OR
 the tumor is larger than 5 centimeters and has spread to axillary lymph nodes that are clumped
together or sticking to other structures

Stage IIIB describes invasive breast cancer in which:

 the tumor may be any size and has spread to the chest wall and/or skin of the breast AND
 may have spread to axillary lymph nodes that are clumped together or sticking to other
structures, or cancer may have spread to lymph nodes near the breastbone
 Inflammatory breast cancer is considered at least stage IIIB.

Stage IIIC describes invasive breast cancer in which:

 there may be no sign of cancer in the breast or, if there is a tumor, it may be any size and may
have spread to the chest wall and/or the skin of the breast, AND
 the cancer has spread to lymph nodes above or below the collarbone, AND
 the cancer may have spread to axillary lymph nodes or to lymph nodes near the breastbone
Stage IV
Stage IV describes invasive breast cancer in which:

 the cancer has spread to other organs of the body -- usually the lungs, liver, bone, or brain

"Metastatic at presentation" means that the breast cancer has spread beyond the breast and
nearby lymph nodes, even though this is the first diagnosis of breast cancer. The reason for this
is that the primary breast cancer was not found when it was only inside the breast. Metastatic
cancer is considered stage IV.

Additional staging information

You may also hear terms such as "early" or "earlier" stage, "later," or "advanced" stage breast
cancer. Although these terms are not medically precise (they may be used differently by different
doctors), here is a general idea of how they apply to the official staging system:

Early stage

 Stage 0
 Stage I
 Stage II
 Some stage III 

Later or advanced stage

 Other stage III

 Stage IV

Doctors use a staging system to determine how far a cancer has spread. The most common
system is the TNM staging system. You may hear the cancer described by three characteristics:

 size (T stands for tumor)

 lymph node involvement (N stands for node)
 whether it has metastasized (M stands for metastasis)

The T (size) category describes the original (primary) tumor:

 TX means the tumor can't be measured or found.

 T0 means there isn't any evidence of the primary tumor.
 Tis means the cancer is "in situ" (the tumor has not started growing into the breast tissue).
 The numbers T1-T4 describe the size and/or how much the cancer has grown into the breast
tissue. The higher the T number, the larger the tumor and/or the more it may have grown into
the breast tissue.
The N (node involvement) category describes whether or not the cancer has reached nearby
lymph nodes:

 NX means the nearby lymph nodes can't be measured or found.

 N0 means nearby lymph nodes do not contain cancer.
 The numbers N1-N3 describe the size, location, and/or the number of lymph nodes involved.
The higher the N number, the more the lymph nodes are involved.

The M (metastasis) category tells whether there are distant metastases (whether the cancer has
spread to other parts of body):

 MX means metastasis can't be measured or found.

 M0 means there are no distant metastases.
 M1 means that distant metastases were found.

Once the pathologist knows your T, N, and M characteristics, they are combined in a process
called stage grouping, and an overall stage is assigned.

For example, a T1, N0, M0 breast cancer would mean that the primary breast tumor:

 is less than 2 centimeters across (T1)

 does not have lymph node involvement (N0)
 has not spread to distant parts of the body (M0)

This cancer would be grouped as a stage I ca

Breast profile:
A Ducts
B Lobules
C Dilated section of duct to hold milk
D Nipple
E Fat
F Pectoralis major muscle
G Chest wall/rib cage

Enlargement
A Normal duct cells
B Basement membrane
C Lumen (center of duct)