Breast cancer : Overview, Causes, & Risk Factors

Alternate Names : Cancer – breast, Carcinoma – ductal, Carcinoma – lobular, DCIS, LCIS, HER2-positive breast cancer, ER-positive breast cancer, Ductal carcinoma in situ, Lobular carcinoma in situ

Definition

Breast cancer is a cancer that starts in the tissues of the breast.

There are two main types of breast cancer:

  • Ductal carcinoma starts in the tubes (ducts) that move milk from the breast to the nipple. Most breast cancers are of this type.
  • Lobular carcinoma starts in parts of the breast, called lobules, that produce milk.

In rare cases, breast cancer can start in other areas of the breast.

Breast cancer may be invasive or noninvasive. Invasive means it has spread to other tissues. Noninvasive means it has not yet spread. Noninvasive breast cancer is referred to as “in situ.”

  • Ductal carcinoma in situ (DCIS), or intraductal carcinoma, is breast cancer in the lining of the milk ducts that has not yet invaded nearby tissues. It may progress to invasive cancer if untreated.
  • Lobular carcinoma in situ (LCIS) is a marker for an increased risk of invasive cancer in the same or both breasts.

Many breast cancers are sensitive to the hormone estrogen. This means that estrogen causes the breast cancer tumor to grow. Such cancers have estrogen receptors on the surface of their cells. They are called estrogen receptor-positive cancer or ER-positive cancer.

Some women have what’s called HER2-positive breast cancer. HER2 refers to a gene that helps cells grow, divide, and repair themselves. When cells have too many copies of this gene, cells — including cancer cells — grow faster. Experts think that women with HER2-positive breast cancer have a more aggressive disease and a higher risk of recurrence than those who do not have this type.

Overview, Causes, & Risk Factors

Over the course of a lifetime, 1 in 8 women will be diagnosed with breast cancer.

Risk factors you cannot change include:

  • Age and gender — Your risk of developing breast cancer increases as you get older. The majority of advanced breast cancer cases are found in women over age 50. Women are 100 times more likely to get breast cancer then men.
  • Family history of breast cancer — You may also have a higher risk for breast cancer if you have a close relative who has had breast, uterine, ovarian, or colon cancer. About 20 – 30% of women with breast cancer have a family history of the disease.
  • Genes — Some people have genes that make them more prone to developing breast cancer. The most common gene defects are found in the BRCA1 and BRCA2 genes. These genes normally produce proteins that protect you from cancer. But if a parent passes you a defective gene, you have an increased risk for breast cancer. Women with one of these defects have up to an 80% chance of getting breast cancer sometime during their life.
  • Menstrual cycle — Women who get their periods early (before age 12) or went through menopause late (after age 55) have an increased risk for breast cancer.

Other risk factors include:

  • Alcohol use — Drinking more than 1 – 2 glasses of alcohol a day may increase your risk for breast cancer.
  • Childbirth — Women who have never had children or who had them only after age 30 have an increased risk for breast cancer. Being pregnant more than once or becoming pregnant at an early age reduces your risk of breast cancer.
  • DES — Women who took diethylstilbestrol (DES) to prevent miscarriage may have an increased risk of breast cancer after age 40. This drug was given to the women in the 1940s – 1960s.
  • Hormone replacement therapy (HRT) — You have a higher risk for breast cancer if you have received hormone replacement therapy for several years or more. Many women take HRT to reduce the symptoms of menopause.
  • Obesity — Obesity has been linked to breast cancer, although this link is controversial. The theory is that obese women produce more estrogen, which can fuel the development of breast cancer.
  • Radiation — If you received radiation therapy as a child or young adult to treat cancer of the chest area, you have a significantly higher risk for developing breast cancer. The younger you started such radiation and the higher the dose, the higher your risk — especially if the radiation was given when a female was developing breasts.

Breast implants, using antiperspirants, and wearing underwire bras do not raise your risk for breast cancer. There is no evidence of a direct link between breast cancer and pesticides.

The National Cancer Institute provides an online tool to help you figure out your risk of breast cancer. See: www.cancer.gov/bcrisktool

Pictures & Images

Female breast

The female breast is either of two mammary glands (organs of milk secretion) on the chest.

Needle biopsy of the breast

Needle biopsy of the breast

A needle biopsy is performed under local anesthesia. Simple aspirations are performed with a small gauge needle to attempt to draw fluid from lumps that are thought to be cysts. Fine needle biopsy uses a larger needle to make multiple passes through a lump, drawing out tissue and fluid. Withdrawn fluid and tissue is further evaluated to determine if there are cancerous cells present.

Open biopsy of the breast

Open biopsy of the breast

An open biopsy can be performed under local or general anesthesia and will leave a small scar. Prior to surgery, a radiologist often first marks the lump with a wire, making it easier for the surgeon to find.

Breast self-exam

Breast self-exam

Monthly breast self-exams should always include: visual inspection (with and without a mirror) to note any changes in contour or texture; and manual inspection in standing and reclining positions to note any unusual lumps or thicknesses.

Breast self-exam

Breast self-exam

Monthly breast self-exams should always include: visual inspection (with and without a mirror) to note any changes in contour or texture; and manual inspection in standing and reclining positions to note any unusual lumps or thicknesses.

Breast self-exam

Breast self-exam

Monthly breast self-exams should always include: visual inspection (with and without a mirror) to note any changes in contour or texture; and manual inspection in standing and reclining positions to note any unusual lumps or thicknesses.

Mammary gland

Mammary gland

The anatomy of the breast includes the lactiferous, or milk ducts, and the mammary lobules.

Sentinel node biopsy

Sentinel node biopsy

Sentinel node biopsy is a technique which helps determine if a cancer has spread (metastasized), or is contained locally. When a cancer has been detected, often the next step is to find the lymph node closest to the tumor site and retrieve it for analysis. The concept of the “sentinel” node, or the first node to drain the area of the cancer, allows a more accurate staging of the cancer, and leaves unaffected nodes behind to continue the important job of draining fluids. The procedure involves the injection of a dye (sometimes mildly radioactive) to pinpoint the lymph node which is closest to the cancer site. Sentinel node biopsy is used to stage many kinds of cancer, including lung and skin (melanoma).

Mastectomy – series
Normal anatomy

Mastectomy - series : Normal anatomy

Breast cancer begins in the breast and spreads first to the lymph nodes of the armpit (axilla). When a breast lump is found to contain cancer, and if the cancer has not spread beyond the nodes of the axilla to distant sites, it is often removed surgically. Radiation therapy may be used in addition to surgery. In certain cases of malignant lumps, lumpectomy followed by radiation therapy is as effective as a radical mastectomy. Typically, lumpectomy does not require a breast replacement (prosthesis).

Breast lump removal – series
Normal anatomy

Breast lump removal  - series : Normal anatomy

The female breast is composed mainly of fatty tissue interspersed with fibrous or connective tissue. The circular region around the nipple is often a different color or pigmented. This region is called the areola.


Review Date : 12/27/2009
Reviewed By : David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc., and Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only — they do not constitute endorsements of those other sites. © 1997- 2010 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

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