Causes and risk factors

from: http://www.nhs.uk/Conditions/Cancer-of-the-breast-female/Pages/Causes.aspx
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Causes and risk factors 

The causes of breast cancer are not fully understood. This means it is difficult to say why one woman may develop breast cancer and another may not.

Some things, known as risk factors, can change the likelihood that someone may develop breast cancer. There are some factors you cannot do anything about. Others, you can change.

Age

The risk of developing breast cancer increases as you get older. Breast cancer is most common among women over 50 who have been through the menopause. Eight out of 10 cases of breast cancer occur in women over 50.

All women between 50 and 70 years of age should be screened for breast cancer every three years as part of the NHS Breast Screening Programme. Women over the age of 70 are still eligible to be screened and can arrange this through their GP or local screening unit. Currently, there are ongoing pilot studies looking at widening the screening age range to 47-73.

Family history

If you have close relatives who have had breast cancer or ovarian cancer, you may have a higher risk of developing breast cancer. However, as breast cancer is the most common cancer in women, it is possible for it to occur more than once in the same family by chance.

Most breast cancer cases are not hereditary (they do not run in families). However, particular genes, known as BRCA1 and BRCA2, can increase your risk of developing both breast and ovarian cancer. It is possible for these genes to be passed on from a parent to their child. A third gene (TP53) is also associated with increased risk of breast cancer.

If you have, for example, two or more close relatives from the same side of your family (such as your mother, sister or daughter) who have had breast cancer under the age of 50, you may be eligible for surveillance for breast cancer or for genetic screening to look for the genes that make developing breast cancer more likely. If you are worried about your family history of breast cancer, discuss it with your GP.

Previous diagnosis of breast cancer

If you have previously had breast cancer or early non-invasive cancer cell changes contained within breast ducts, you have a higher risk of developing it again, either in your other breast or in the same breast again.

Previous benign breast lump

A benign breast lump does not mean you have breast cancer, but certain types of lump may slightly increase your risk of developing it. Certain benign changes in your breast tissue, such as atypical ductal hyperplasia (cells growing abnormally in ducts) or lobular carcinoma in situ (abnormal cells inside your breast lobes), can make getting breast cancer more likely.

Breast density

Your breasts are made up of thousands of tiny glands (lobules), which produce milk. This glandular tissue contains a higher concentration of breast cells than other breast tissue, making it denser. Women with more dense breast tissue may have a higher risk of developing breast cancer because there are more cells that can become cancerous.

Dense breast tissue can also make a breast scan (mammogram) harder to read because it makes any lumps or areas of abnormal tissue harder to spot. Younger women tend to have denser breasts. As you get older, the amount of glandular tissue in your breasts decreases and is replaced by fat, so your breasts become less dense.

Exposure to oestrogen

In some cases, breast cancer cells can be stimulated to grow by the female hormone oestrogen. Your ovaries, where your eggs are stored, begin to produce oestrogen when you start puberty in order to regulate your periods.

Your risk of developing breast cancer may rise slightly with the amount of oestrogen your body is exposed to. For example, if you started your periods at a young age and entered menopause at a late age, you will have been exposed to oestrogen over a longer period of time. In the same way, not having children, or having children later in life, may slightly increase your risk of developing breast cancer because your exposure to oestrogen is uninterrupted by pregnancy.

Being overweight or obese

If you have been through the menopause and are overweight orobese, you may be more at risk of developing breast cancer. This is thought to be linked to the amount of oestrogen in your body, as being overweight or obese after the menopause causes more oestrogen to be produced.

Being tall

If you are taller than average, you are more likely to develop breast cancer than someone who is shorter than average. This may be due to interactions between genes, nutrition and hormones, but the reason is not fully understood.

Alcohol

Your risk of developing breast cancer can increase with the amount of alcohol you drink. Research shows that, for every 200 women who regularly have two alcoholic drinks a day, there are three more women with breast cancer compared with women who do not drink at all.

Radiation

Certain medical procedures that use radiation, such as X-rays and CT scans, may slightly increase your risk of developing breast cancer. If you had radiotherapy to your chest area for Hodgkin's lymphoma when you were a child, you should have already received a written invitation from the Department of Health for a consultation with a specialist to discuss your increased risk of developing breast cancer. See your GP if you were not contacted or you did not attend a consultation.

If you currently need radiotherapy for Hodgkin's lymphoma, your specialist should discuss the risk of breast cancer before your treatment begins.

Hormone replacement therapy (HRT)

Hormone replacement therapy (HRT) is associated with a slightly increased risk of developing breast cancer. Both combined HRT and oestrogen-only HRT can increase your risk of developing breast cancer, although the risk is slightly higher if you take combined HRT.

It is estimated there will be an extra 19 cases of breast cancer for every 1,000 women taking combined HRT for 10 years. The risk continues to increase slightly the longer you take HRT, but returns to normal once you stop taking it.

Want to know more?

• Breakthrough Breast Cancer: Breast cancer risk factors
• Breast Cancer Care: Risk
• Cancer Research UK: Breast cancer risks and causes
• Live Well: Breast cancer genes
• Macmillan: Breast cancer causes and risk factors

Page last reviewed: 09/07/2012

Next review due: 09/07/2014

key statistics about breast cancer

from: http://www.cancer.org/cancer/breastcancer/detailedguide/breast-cancer-key-statistics
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What are the key statistics about breast cancer?

Breast cancer is the most common cancer among American women, except for skin cancers. About 1 in 8 (12%) women in the US will develop invasive breast cancer during their lifetime.

The American Cancer Society's estimates for breast cancer in the United States are for 2013:

• About 232,340 new cases of invasive breast cancer will be diagnosed in women.
• About 64,640 new cases of carcinoma in situ (CIS) will be diagnosed (CIS is non-invasive and is the earliest form of breast cancer).
• About 39,620 women will die from breast cancer

After increasing for more than 2 decades, female breast cancer incidence rates began decreasing in 2000, then dropped by about 7% from 2002 to 2003. This large decrease was thought to be due to the decline in use of hormone therapy after menopause that occurred after the results of the Women's Health Initiative were published in 2002. This study linked the use of hormone therapy to an increased risk of breast cancer and heart diseases. Incidence rates have been stable in recent years.

Breast cancer is the second leading cause of cancer death in women, exceeded only by lung cancer. The chance that breast cancer will be responsible for a woman's death is about 1 in 36 (about 3%). Death rates from breast cancer have been declining since about 1989, with larger decreases in women younger than 50. These decreases are believed to be the result of earlier detection through screening and increased awareness, as well as improved treatment.

At this time there are more than 2.9 million breast cancer survivors in the United States. (This includes women still being treated and those who have completed treatment.) Survival rates are discussed in the section “How is breast cancer staged?”

Last Medical Review: 08/23/2012
Last Revised: 02/26/2013

from: http://www.cancer.org/cancer/breastcancer/detailedguide/breast-cancer-breast-cancer-types
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Types of breast cancers

There are several types of breast cancer, but some of them are quite rare. In some cases a single breast tumor can be a combination of these types or be a mixture of invasive and in situ cancer.

Ductal carcinoma in situ

Ductal carcinoma in situ (DCIS; also known as intraductal carcinoma) is the most common type of non-invasive breast cancer. DCIS means that the cancer cells are inside the ducts but have not spread through the walls of the ducts into the surrounding breast tissue.

About 1 in 5 new breast cancer cases will be DCIS. Nearly all women diagnosed at this early stage of breast cancer can be cured. A mammogram is often the best way to find DCIS early.

When DCIS is diagnosed, the pathologist (a doctor specializing in diagnosing disease from tissue samples) will look for areas of dead or dying cancer cells, called tumor necrosis, within the tissue sample. If necrosis is present, the tumor is likely to be more aggressive. The term comedocarcinoma is often used to describe DCIS with large areas of necrosis. The pathologist will also note how abnormal the cells appear, especially the part of cells where DNA is found (the nucleus).

Lobular carcinoma in situ

This is not a true cancer or pre-cancer, and is discussed in the section “What are the risk factors for breast cancer?”

Invasive (or infiltrating) ductal carcinoma

This is the most common type of breast cancer. Invasive (or infiltrating) ductal carcinoma (IDC) starts in a milk duct of the breast, breaks through the wall of the duct, and grows into the fatty tissue of the breast. At this point, it may be able to spread (metastasize) to other parts of the body through the lymphatic system and bloodstream. About 8 of 10 invasive breast cancers are infiltrating ductal carcinomas.

Invasive (or infiltrating) lobular carcinoma

Invasive lobular carcinoma (ILC) starts in the milk-producing glands (lobules). Like IDC, it can spread (metastasize) to other parts of the body. About 1 invasive breast cancer in 10 is an ILC. Invasive lobular carcinoma may be harder to detect by a mammogram than invasive ductal carcinoma.

Less common types of breast cancer

Inflammatory breast cancer: This uncommon type of invasive breast cancer accounts for about 1% to 3% of all breast cancers. Usually there is no single lump or tumor. Instead, inflammatory breast cancer (IBC) makes the skin on the breast look red and feel warm. It also may give the breast skin a thick, pitted appearance that looks a lot like an orange peel. Doctors now know that these changes are not caused by inflammation or infection, but by cancer cells blocking lymph vessels in the skin. The affected breast may become larger or firmer, tender, or itchy.

In its early stages, inflammatory breast cancer is often mistaken for an infection in the breast (called mastitis) and treated as an infection with antibiotics. If the symptoms are caused by cancer, they will not improve, and a biopsy will find cancer cells. Because there is no actual lump, it might not show up on a mammogram, which can make it even harder to find it early. This type of breast cancer tends to have a higher chance of spreading and a worse outlook (prognosis) than typical invasive ductal or lobular cancer. For more details about this condition, see our document,Inflammatory Breast Cancer.

Triple-negative breast cancer: This term is used to describe breast cancers (usually invasive ductal carcinomas) whose cells lack estrogen receptors and progesterone receptors, and do not have an excess of the HER2 protein on their surfaces. (See the section, "How is breast cancer diagnosed?" for more detail on these receptors.) Breast cancers with these characteristics tend to occur more often in younger women and in African-American women. Triple-negative breast cancers tend to grow and spread more quickly than most other types of breast cancer. Because the tumor cells lack these certain receptors, neither hormone therapy nor drugs that target HER2 are effective treatments (but chemotherapy can still be useful if needed).

Paget disease of the nipple: This type of breast cancer starts in the breast ducts and spreads to the skin of the nipple and then to the areola, the dark circle around the nipple. It is rare, accounting for only about 1% of all cases of breast cancer. The skin of the nipple and areola often appears crusted, scaly, and red, with areas of bleeding or oozing. The woman may notice burning or itching.

Paget disease is almost always associated with either ductal carcinoma in situ (DCIS) or infiltrating ductal carcinoma. Treatment often requires mastectomy. If no lump can be felt in the breast tissue, and the biopsy shows DCIS but no invasive cancer, the outlook (prognosis) is excellent. If invasive cancer is present, the prognosis is not as good, and the cancer will need to be staged and treated like any other invasive cancer.

Phyllodes tumor: This very rare breast tumor develops in the stroma (connective tissue) of the breast, in contrast to carcinomas, which develop in the ducts or lobules. Other names for these tumors include phylloides tumor andcystosarcoma phyllodes. These tumors are usually benign but on rare occasions may be malignant.

Benign phyllodes tumors are treated by removing the tumor along with a margin of normal breast tissue. A malignant phyllodes tumor is treated by removing it along with a wider margin of normal tissue, or by mastectomy. Surgery is often all that is needed, but these cancers might not respond as well to the other treatments used for more common breast cancers. When a malignant phyllodes tumor has spread, it can be treated with the chemotherapy given for soft-tissue sarcomas (this is discussed in detail in our document, Sarcoma - Adult Soft Tissue Cancer.

Angiosarcoma: This form of cancer starts in cells that line blood vessels or lymph vessels. It rarely occurs in the breasts. When it does, it usually develops as a complication of previous radiation treatments. This is an extremely rare complication of breast radiation therapy that can develop about 5 to 10 years after radiation. Angiosarcoma can also occur in the arms of women who develop lymphedema as a result of lymph node surgery or radiation therapy to treat breast cancer. (For information on lymphedema, see the section, "How is breast cancer treated?") These cancers tend to grow and spread quickly. Treatment is generally the same as for other sarcomas. See our document,Sarcoma - Adult Soft Tissue Cancer.

Special types of invasive breast carcinoma

There are some special types of breast cancer that are sub-types of invasive carcinoma. These are often named after features seen when they are viewed under the microscope, like the ways the cells are arranged.

Some of these may have a better prognosis than standard infiltrating ductal carcinoma. These include:

• Adenoid cystic (or adenocystic) carcinoma
• Low-grade adenosquamous carcinoma (this is a type of metaplastic carcinoma)
• Medullary carcinoma
• Mucinous (or colloid) carcinoma
• Papillary carcinoma
• Tubular carcinoma

Some sub-types have the same or maybe worse prognosis than standard infiltrating ductal carcinoma. These include:

• Metaplastic carcinoma (most types, including spindle cell and squamous)
• Micropapillary carcinoma
• Mixed carcinoma (has features of both invasive ductal and lobular)

In general, all of these sub-types are still treated like standard infiltrating ductal carcinoma.

Last Medical Review: 08/23/2012
Last Revised: 02/26/2013

What is Breast Cancer?

from: http://www.breastcancer.org/symptoms/understand_bc/what_is_bc
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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 AnatomyLarger 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 the Stages of breast cancer tablefor 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.

There are steps every person can take to help the body stay as healthy as possible and lower risk of breast cancer or a breast cancer recurrence (such as maintaining a healthy weight, not smoking, limiting alcohol, and exercising regularly). Learn what you can do to manage breast cancer risk factors.

Always remember, 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 cancer

Stage	Definition
Stage 0	Cancer cells remain inside the breast duct, without invasion into normal adjacent breast tissue.
Stage IA	The tumor measures up to 2 cm  AND  the cancer has not spread outside the breast; no lymph nodes are involved
Stage IB	There is no tumor in the breast; instead, small groups of cancer cells -- larger than 0.2 millimeter but not larger than 2 millimeters – are found in the lymph nodes  OR  there is a tumor in the breast that is no larger than 2 centimeters, and there are small groups of cancer cells – larger than 0.2 millimeter but not larger than 2 millimeters – in the lymph nodes.
Stage IIA	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 smaller and has spread to the axillary lymph nodes  OR  the tumor is larger than 2 but no larger than 5 centimeters and has not spread to the axillary lymph nodes.
Stage IIB	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 IIIA	No tumor is found in the breast. Cancer is found in axillary lymph nodes that are sticking together or to other structures, or cancer may be found in lymph nodes near the breastbone  OR  the tumor is any size. Cancer has spread to the axillary lymph nodes, which are sticking together or to other structures, or cancer may be found in lymph nodes near the breastbone.
Stage IIIB	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	There may either be no sign of cancer in the breast or a tumor 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 either above or below the collarbone  AND  the cancer may have spread to axillary lymph nodes or to lymph nodes near the breastbone.
Stage IV	The cancer has spread — or metastasized — to other parts of the body.

For more information about staging, please visit the Stages of Breast Cancer page.

What is Breast Cancer? Definition, Types of Breast Cancer, Common Symptoms

from: http://breastcancer.about.com/od/definition/a/bc_definition.htm
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Breast cancer is a malignant (cancerous) growth that begins in the tissues of the breast. Cancer is a disease in which abnormal cells grow in an uncontrolled way. Breast cancer is the most common cancer in women, but it can also appear in men. In the U.S., it affects one in eight women.

The most common types of breast cancer are:

• ductal carcinoma (85 - 90% of all cases)
• lobular carcinoma (8% of all cases)

Invasive (Infiltrating) Breast Cancer
Invasive, or infiltrating, breast cancer has the potential to spread out of the original tumor site and invade other parts of your breast and body. There are several types and subtypes of invasive breast cancer.

Less common are:

• inflammatory breast cancer (occurs in the skin)
• Paget's disease of the nipple

Symptoms of Breast Cancer:

• a lump or a thickening in the breast or in the armpit
• a change of size or shape of the mature breast
• nipple fluid (not milk) leaking
• a change of size or shape of the nipple
• a change of color or texture of the nipple or theareola, or of the skin of the breast itself (dimples, puckers, rash)
• More details about symptoms of breast cancer.

If You Have Breast Pain

Early stages of breast cancer may not cause any pain or discomfort. Having a regularmammogram and a clinical breast exam by your health professional can help you understand changes in your breasts. Doing your breast self-exam can help you keep track of regular monthly changes.

Remember, many lumps and rashes are benign (not cancerous) and can respond well to proper treatment. If you experience any symptoms that cause you concern, see your doctor.

Treatments for breast cancer, as well as survival rates, are improving. Early detection and medical help is critical to improving the chances of living beyond a diagnosis of breast cancer.

Read about breast cancer symptoms and their explanations.