Monday, 23 January 2012

Causes of Breast Cancer

Breast Overview

Breast cancer is the most common cancer in women, being responsible for almost 20 percent of all cancer deaths in women. It ranks second after lung cancer. Roughly 180,000 women are diagnosed with this disease each year, of which 44,000
will die. With increased awareness and increased use of routine mammograms, more women are diagnosed in the earlier stages of this disease, at which time a cure may be possible. For every 100 women, one man is diagnosed with this disease. The disease is more common in women after age 40. It is also more frequent in women of a higher social-economic class.
  •       History of breast cancer in a first-degree relative
  •       History of breast cancer in the same patient, in the opposite breast
  •       Onset of menstruation in early ages
  •       Late onset of menopause
  •       Radiation exposure
  •       Heavy alcohol consumption
  •       High fat diet
  •       Obesity
  •       First pregnancy after age of 30
  •       Very tall women 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's disease before 30 years of age have a significantly higher rate of breast cancer than the general population. 
  • 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.
Exams and Tests
Diagnosis of breast cancer usually is comprised of several steps, including examination of the breast, mammography, possibly ultrasonography or MRI, and, finally, biopsy. Biopsy is the only definitive way to diagnose breast cancer.
Examination of the Breast
    * A complete breast examination includes visual inspection and careful palpation (feeling) of the breasts, the armpits, and the areas around your collarbone.
    * During that exam, your health-care provider may palpate a lump or just feel a thickening.  
1. Mammography
    * Mammograms are x-rays of the breast that may help define the nature of a lump. Mammograms are also recommended for screening to find early cancer.
    * Usually, it is possible to tell from the mammogram whether a lump in the breast is breast cancer, but no test is 100% reliable. Mammograms are thought to miss as many as 10-15% of breast cancers.
    * A false-positive mammogram is one that suggests malignancy (cancer) when no malignancy is found on biopsy.
    * A false-negative mammogram is one that appears normal when in fact cancer is present.
    * A mammogram alone is often not enough to evaluate a lump. Your health-care provider will probably request additional tests.
    * All breast lumps need to be clearly defined as benign or should be biopsied.
    * Ultrasound of the breast is often done to evaluate a breast lump.
    * Ultrasound waves create a "picture" of the inside of the breast.
    * It can demonstrate whether a mass is filled with fluid (cystic) or solid. Cancers are usually solid, while many cysts are benign.
    * Ultrasound might also be used to guide a biopsy or the removal of fluid.  
2. MRI
      MRI may provide additional information and may clarify findings which have been seen on mammography or ultrasound.
MRI is not routine for screening for cancer but may be recommended in special situations. 3. Biopsy
   The only way to diagnose breast cancer with certainty is to biopsy the tissue in question. Biopsy means to take a very small piece of tissue from the body for examination and testing by a pathologist to determine if cancer is present. A number of biopsy techniques are available.
     Fine-needle aspiration consists of placing a needle into the breast and sucking out some cells to be examined by a pathologist. This technique is used most commonly when a fluid-filled mass is identified and cancer is not likely.
     Core-needle biopsy is performed with a special needle that takes a small piece of tissue for examination. Usually the needle is directed into the suspicious area with ultrasound or mammogram guidance. This technique is being used more and more because it is less invasive than surgical biopsy. It obtains only a sample of tissue rather than removing an entire lump. Occasionally, if the mass is easily felt, cells may be removed with a needle without additional guidance.
       Surgical biopsy is done by making an incision in the breast and removing the piece of tissue. Certain techniques allow removal of the entire lump.
      Regardless of how the biopsy is taken, the tissue will be reviewed by a pathologist. These are physicians who are specially trained in diagnosing diseases by looking at cells and tissues under a microscope.
      If a cancer is diagnosed on biopsy, the tissue will be tested for hormone receptors. Receptors are sites on the surface of tumor cells that bind to estrogen or progesterone. In general, the more receptors, the more sensitive the tumor will be to hormone therapy. There are also other tests (for example, measurement of HER-2/neu receptors) that may be performed to help characterize a tumor and determine the type of treatment that will be most effective for a given tumor.   
Breast Cancer Treatment
 Surgery is the mainstay of therapy for breast cancer. The choice of which type of surgery is based on a number of factors, including the size and location of the tumor, the type of tumor and the person's overall health and personal wishes. Breast-sparing surgery is often possible.
The cancer is staged, using the information from surgery and from other tests. Staging is a classification that reflects the extent and spread of a tumor and has an impact on treatment decisions and also the prognosis for recovery.
    * Staging in breast cancer is based on the size of the tumor, which parts of the breast are involved, how many and which lymph nodes are affected, and whether the cancer has metastasized to another part of the body.
    * Cancers may be referred to as invasive if they have spread to other tissues. Those that do not spread to other tissues are called noninvasive. Carcinoma in situ is a noninvasive cancer.
Breast cancer is staged from 0 to IV.
    * Stage 0 is noninvasive breast cancer, that is, carcinoma in situ with no affected lymph nodes or metastasis. This is the most favorable stage of breast cancer.
    * Stage I is breast cancer that is less than 2 cm (3/4 in) in diameter and has not spread from the breast.
    * Stage II is breast cancer that is fairly small in size but has spread to lymph nodes in the armpit OR cancer that is somewhat larger but has not spread to the lymph nodes.
    * Stage III is breast cancer of a larger size, greater than 5 cm (2 in), with greater lymph node involvement, or of the inflammatory type.
    * Stage IV is metastatic breast cancer: a tumor of any size or type that has metastasized to another part of the body. This is the least favorable stage.

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