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Emedicine Breast Cancer

By 10 Apr, 2013 BREAST CANCER EDUCATIONAL SERIES

Breast Cancer

Breast Cancer Overview

Breast cancer is cancer arising in breast tissue. Cancer is simply a group of abnormal cells that have abnormal growth patterns.

  • Although breast cancer is primarily a disease of women, almost 1% of breast cancers occur in men. In 2007, it is estimated that 2,030 men in the U.S. will develop invasive breast cancer.
  • Breast cancer is the most common type of cancer in women with the exception of nonmelanoma skin cancers. It is the second leading cause of death by cancer in women, following only lung cancer.
  • In 2007, the American Cancer Society estimated that 178,480 new cases of invasive breast cancer would be diagnosed among women in the United States, and that a further 62,030 new cases of in-situ (noninvasive) breast cancer would be diagnosed.
  • A woman has a lifetime risk of developing invasive breast cancer of about one in eight, or 13%.
  • Death rates from breast cancer have been gradually declining and continue to decline. These decreases are likely due both to increased awareness and screening and improved treatment methods.

The breasts are made of fat, glands, and connective (fibrous) tissue. The breast has several lobes, which are divided into lobules that end in the milk glands. Tiny ducts run from the many tiny glands, connect together, and end in the nipple.

  • These ducts are where 80% of breast cancers occur. This condition is called ductal cancer.
  • Cancer developing in the lobules is termed lobular cancer. About 10-15% of breast cancers are of this type.
  • Other less common types of breast cancer include inflammatory breast cancer, medullary cancer, phyllodes tumor, angiosarcoma, mucinous (colloid) carcinoma, mixed tumors, and a type of cancer involving the nipple termed Paget’s disease.

Precancerous changes, called in situ changes, are common.

  • In situ is Latin for “in place” or “in site” and means that the changes haven’t spread from where they started.
  • When these in situ changes occur in the ducts, they are called ductal carcinoma in situ (DCIS). DCIS may be identified on routine mammography.
  • When in-situ changes happen in the lobules, it is called lobular carcinoma in situ (LCIS).

When cancers spread into the surrounding tissues, they are termed infiltrating cancers. Cancers spreading from the ducts into adjacent spaces are termed infiltrating ductal carcinomas. Cancers spreading from the lobules are infiltrating lobular carcinomas.

The most serious cancers are metastatic cancers. Metastasis means that the cancer has spread from the place where it started into other tissues distant from the original tumor site. The most common place for breast cancer to metastasize is into the lymph nodes under the arm or above the collarbone on the same side as the cancer. Other common sites of breast cancer metastasis are the brain, the bones, and the liver.

IN THIS ARTICLE

Breast Cancer Causes

Many women who develop breast cancer have no risk factors other than age and sex.

  • Gender is the biggest risk because breast cancer occurs mostly in women.
  • Age is another critical factor. Breast cancer may occur at any age, though the risk of breast cancer increases with age. The average woman at age 30 years has one chance in 280 of developing breast cancer in the next 10 years. This chance increases to one in 70 for a woman aged 40 years, and to one in 40 at age 50 years. A 60-year-old woman has a one in 30 chance of developing breast cancer in the next 10 years.
  • White women are slightly more likely to develop breast cancer than African American women in the U.S.
  • A woman with a personal history of cancer in one breast has a three- to fourfold greater risk of developing a new cancer in the other breast or in another part of the same breast. This refers to the risk for developing a new tumor and not a recurrence (return) of the first cancer.

Genetic Causes

Family history has long been known to be a risk factor for breast cancer. Both maternal and paternal relatives are important. The risk is highest if the affected relative developed breast cancer at a young age, had cancer in both breasts, or if she is a close relative. First-degree relatives, (mother, sister, daughter) are most important in estimating risk. Several second-degree relatives (grandmother, aunt) with breast cancer may also increase risk. Breast cancer in a male increases the risk for all his close female relatives. Having relatives with both breast and ovarian cancer also increases a woman’s risk of developing breast cancer.

There is great interest in genes linked to breast cancer. About 5-10% of breast cancers are believed to be hereditary, as a result of mutations, or changes, in certain genes that are passed along in families.

  • BRCA1 and BRCA2 are abnormal genes that, when inherited, markedly increase the risk of breast cancer to a lifetime risk estimated between 40 and 85%. Women with these abnormal genes also have an increased likelihood of developing ovarian cancer. Women who have the BRCA1 gene tend to develop breast cancer at an early age.
  • Testing for these genes is expensive and may not be covered by insurance.
  • The issues around testing are complicated, and women who are interested in testing should discuss this with their health-care providers.

Hormonal Causes

Hormonal influences play a role in the development of breast cancer.

  • Women who start their periods at an early age (11 or younger) or experience a late menopause (55 or older) have a slightly higher risk of developing breast cancer. Conversely, being older at the time of the first menstrual period and early menopause tend to protect one from breast cancer.
  • Having a child before age 30 years may provide some protection, and having no children may increase the risk for developing breast cancer.
  • Oral contraceptives have not been shown to definitively increase or decrease a woman’s lifetime risk of breast cancer.
  • A large study conducted by the Women’s Health Initiative showed an increased risk of breast cancer in postmenopausal women who were on a combination of estrogen and progesterone for several years. Therefore, women who are considering hormone therapy for menopausal symptoms need to discuss the risk versus the benefit with their health-care providers.

Lifestyle and Dietary Causes

Breast cancer seems to occur more frequently in countries with high dietary intake of fat, and being overweight or obese is a known risk factor for breast cancer, particularly in postmenopausal women.

  • This link is thought to be an environmental influence rather than genetic. For example, Japanese women, at low risk for breast cancer while in Japan, increase their risk of developing breast cancer after coming to the United States.
  • Several studies comparing groups of women with high- and low-fat diets, however, have failed to show a difference in breast cancer rates.

The use of alcohol is also an established risk factor for the development of breast cancer. The risk increases with the amount of alcohol consumed. Women who consume two to five alcoholic beverages per day have a risk about one and a half times that of nondrinkers for the development of breast cancer. Consumption of one alcoholic drink per day results in a slightly elevated risk.

Studies are also showing that regular exercise may actually reduce a woman’s risk of developing breast cancer. Studies have not definitively established how much activity is needed for a significant reduction in risk. One study from the Women’s Health Initiative (WHI) showed that as little as one and a quarter to two and a half hours per week of brisk walking reduced a woman’s breast cancer risk by 18%.

Benign Breast Disease

  • Fibrocystic breast changes are very common. Fibrocystic breasts are lumpy with some thickened tissue and are frequently associated with breast discomfort, especially right before the menstrual period. This condition does not lead to breast cancer.
  • However, certain other types of benign breast changes, such as those diagnosed on biopsy as proliferative or hyperplastic, do predispose women to the later development of breast cancer.

Environmental Causes

Radiation treatment increases the likelihood of developing breast cancer but only after a long delay. For example, women who received radiation therapy to the upper body for treatment of Hodgkin disease before 30 years of age have a significantly higher rate of breast cancer than the general population.

Breast Cancer (cont.)

IN THIS ARTICLE

Breast Cancer Symptoms

Early breast cancer has no symptoms. It is usually not painful.

Most breast cancer is discovered before symptoms are present, either by finding an abnormality on mammography or feeling a breast lump. A lump in the armpit or above the collarbone that does not go away may be a sign of cancer. Other possible symptoms are breast discharge, nipple inversion, or changes in the skin overlying the breast.

  • Most breast lumps are not cancerous. All breast lumps, however, need to be evaluated by a doctor.
  • Breast discharge is a common problem and is rarely a symptom of cancer. Discharge is most concerning if it is from only one breast or if it is bloody. In any case, all breast discharge should be evaluated.
  • Nipple inversion is a common variant of normal nipples, but nipple inversion that is a new development can be of concern.
  • Changes in the skin of the breast include redness, changes in texture, and puckering. These changes are usually caused by skin diseases but occasionally can be associated with breast cancer.