What is breast cancer?

 

Breast cancer is a disease in which certain

cells in the breast become abnormal and

multiply without control or order to form a

tumor. The most common form of breast

cancer begins in cells lining the ducts that

carry milk to the nipple (ductal cancer). Other

 forms of breast cancer begin in the glands

that produce milk (lobular cancer) or in other

parts of the breast.

 

Early breast cancer usually does not cause

pain and may exhibit no noticeable

symptoms. As the cancer progresses, signs

 and symptoms can include a lump or

thickening in or near the breast; a change in

the size or shape of the breast; nipple

discharge, tenderness, or retraction (turning

 inward); and skin irritation, dimpling, or

scaliness. These changes can occur as part of

 many different conditions, however. Having

one or more of these symptoms does not

mean that a person definitely has breast

cancer.

 

In some cases, cancerous tumors can invade

 

surrounding tissue and spread to other parts

of the body. If breast cancer spreads,

cancerous cells most often appear in the

 bones, liver, lungs, or brain. Tumors that

begin at one site and then spread to other

 areas of the body are called metastatic

cancers.

 

 

A small percentage of all breast cancers

cluster in families. Hereditary cancers are

those associated with inherited gene

mutations. Hereditary breast cancers tend to

occur earlier in life than noninherited

(sporadic) cases and are more likely to involve both breasts.

How common is breast cancer?

Researchers estimate that more than 178,000

new cases of invasive breast cancer will be

diagnosed in U.S. women in 2007. Most breast

 cancers occur in women, but they can also

develop in men. Scientists estimate that more

 than 2,000 new cases of breast cancer will be

diagnosed in men in 2007.

 

An estimated 5 percent to 10 percent of all

breast cancers are hereditary. Particular

mutations in genes associated with breast

cancer are more common among certain

geographic or ethnic groups, such as people of

Ashkenazi (central or eastern European)

Jewish heritage and people of Norwegian,

Icelandic, or Dutch ancestry. Particular

genetic changes occur more frequently in

these groups because they have a shared

ancestry over many generations.

 

What genes are related to breast cancer?

Variations of the BRCA1, BRCA2, CDH1, PTEN,

STK11, and TP53 genes increase the risk of

developing breast cancer.

The AR, ATM, BARD1, BRIP1, CHEK2, DIRAS3,

 ERBB2, NBN, PALB2, RAD50, and RAD51

genes are associated with breast cancer.

Cancers occur when a buildup of genetic

mutations in critical genes—those that control

 cell growth and division or the repair of

damaged DNA—allow cells to grow and divide

uncontrollably to form a tumor. In most

cases, these genetic changes are acquired

during a person's lifetime and are present

in certain cells. These changes, which are

called somatic mutations, are not inherited.

Less commonly, gene mutations inherited

from a parent increase the risk of developing

cancer. In people with these inherited genetic

 changes, additional somatic mutations in

other genes must occur for cancer to develop

In addition to specific genetic changes,

researchers have identified many personal and

 environmental factors that may influence a

person's risk of developing breast cancer.

These factors include gender, age, ethnic

background, a history of previous breast

cancer, certain changes in breast tissue, and

hormonal factors. A history of breast cancer in

 closely related family members is also an

important risk factor, particularly if the cancer

occurred at an early age. Some breast cancers

 that cluster in families are associated with

inherited mutations in particular genes, such

as BRCA1 or BRCA2.

 

BRCA1 and BRCA2 are major genes related to

hereditary breast cancer. Women who have

inherited certain mutations in these genes

have a high risk of developing breast cancer,

ovarian cancer, and several other types of

cancer during their lifetimes. Men with BRCA1

mutations also have an increased risk of

developing breast cancer. Additionally, BRCA1

 mutations are associated with an increased

risk of pancreatic cancer. Mutations in the

BRCA2 gene are associated with an increased

chance of developing male breast cancer and

cancers of the prostate and pancreas. An

aggressive form of skin cancer called

melanoma is also more common among

people who have BRCA2 mutations.

 

Inherited changes in several other genes,

including CDH1, PTEN, STK11, and TP53, have

 been found to increase the risk of developing

breast cancer. Mutations in these genes cause

syndromes that greatly increase the chance of

 developing several types of cancer over a

person's lifetime. Some of these syndromes

also include other signs and symptoms, such

 as the growth of noncancerous (benign)

tumors.

 

Some research suggests that inherited

variants of the ATM, BARD1, BRIP1, CHEK2,

NBN, PALB2, RAD50, and RAD51 genes, as

well as certain versions of the AR gene, may

also be associated with breast cancer risk. Not all studies have shown these connections,

however. Of these genes, ATM and CHEK2 have the strongest evidence of being related to the risk of developing breast cancer.

Noninherited (somatic) mutations also have

been identified in breast tumors. For example,

somatic mutations in the ERBB2 (also called

Her-2/neu), DIRAS3, and TP53 genes have

been associated with some cases of breast

cancer.

Read more about the AR, ATM, BARD1,

BRCA1, BRCA2, BRIP1, CDH1, CHEK2,

DIRAS3, ERBB2, NBN, PALB2, PTEN, RAD50,

RAD51, STK11, and TP53 genes.

 

How do people inherit breast cancer?

 

Most cases of breast cancer are not inherited.

These cancers are associated with genetic

changes that occur only in breast cancer cells

(somatic mutations) and occur during a

person's lifetime.

 

In hereditary breast cancer, the way that

cancer risk is inherited depends on the gene

involved. For example, mutations in the

BRCA1 and BRCA2 genes are inherited in an

autosomal dominant pattern, which means

one copy of the altered gene in each cell is

sufficient to increase a person's chance of

developing cancer. In other cases, the

inheritance of breast cancer risk is unclear. It

 is important to note that people inherit an

increased risk of cancer, not the disease itself.

 Not all people who inherit mutations in these

genes will develop cancer.

Where can I find information about treatment

for breast cancer?

These resources address the management of

breast cancer and may include treatment

providers.

 

You might also find information on treatment

of breast cancer in Educational resources and

Patient support.

 

Where can I find additional information about

breast cancer?

You may find the following resources about

breast cancer helpful. These materials are

written for the general public.

 

You may also be interested in these resources, which are designed for healthcare

professionals and researchers.

 

What other names do people use for breast

cancer?

 

  • Breast cancer, familial
  • Breast carcinoma
  • Cancer of breast
  • Malignant neoplasm of breast
  • malignant tumor of breast
  • Mammary cancer