Breast cancer is cancer arising in breast tissue. Cancer is simply a group of abnormal cells that have abnormal growth patterns.
Breast cancer is the most common type of cancer in women with the exception of non-melanoma skin cancers. It is the second leading cause of death by cancer in women, following only lung cancer.
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.
Breast Cancer Causes
- 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 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.
- 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.
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.
- 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. See “Birth control pills and 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.
- 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.
- 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%.
- 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.
- 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.
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 need to be clearly defined as benign or should be biopsied. 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.
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.
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.
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.
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.
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.
Breast Cancer Prevention
- The most important risk factors for the development of breast cancer are sex, age, and genetics. Because women can do nothing about these risks, regular screening is recommended in order to allow early detection and thus prevent death from breast cancer.
Regular screening includes breast self-examination, clinical breast examination, and mammography.
- Obesity after menopause and excessive alcohol intake may increase the risk of breast cancer slightly. Physically active women may have a lower risk. All women are encouraged to maintain normal body weight, especially after menopause and to limit excess alcohol intake. Hormone replacement should be limited in duration if it is medically required.
- In women who are genetically at high risk for the development of breast cancer, tamoxifen has been shown to significantly decrease the incidence of the disease. Side effects should be carefully discussed with your health-care provider prior to embarking on therapy. A second drug, raloxifene (Evista), which is now being used for the treatment of osteoporosis, also blocks the effects of estrogen and appears to prevent breast cancer.
(information from eMedicineHealth – http://www.emedicinehealth.com/breast_cancer/article_em.htm#Breast%20Cancer%20Overview)
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