What is Breast Cancer?
Breast cancer develops when abnormal breast cells begin to grow out of control. When a group of these cells band together, they form a mass called a tumor. Benign tumors do not spread and are usually not harmful. Malignant tumors, however, spread from their sources and can grow into life-threatening cancers. When amalignant cells leave the breast and invade other parts of the body — a process called metastasis — the chance of successfully treating the disease is greatly diminished.
The majority of breast cancers occur in women, but men can also develop the disease. Still, breast cancer occurs almost entirely in women, and factors relating to the female body are known to affect breast cancer risk.
Recent scientific studies suggest that ovarian hormones play a role in the development of breast cancer. Estrogen, a hormone produced in the ovaries, induces the sex-related changes in women's bodies, including the growth of breast cells. Elevated estrogen levels have been linked to breast cancer risk. This association is partly based on evidence that women who develop breast cancer generally have higher levels of estrogen circulating in their bloodstream than do women without breast cancer. Future studies will assess the degree to which behaviors proven to decrease the body's production of estrogen protect against breast cancer, such as eating a low-fat diet and exercising on a regular basis.
Knowing about the type of cells found in breast tissue is important for understanding the differences among various types of breast cancer. The female breast is comprised of the following types of cells:
Lobules: milk-producing glands
Ducts: tube-like structures that connect lobules and the nipple
Stroma: fatty tissue and ligaments that cover the ducts, lobules, blood vessels and lymphatic vessels (passageways that carry fluid containing immune cells and waste products)
Most breast lumps are benign tumors caused by changes in cysts (fluid-filled sacs found in the breast). The formation of scar tissue around sacs can form lumps, which may result in swelling of the breast, but are often not cancerous.
Types of Breast Cancer
Breast cancers are often described in terms of the tissues in which they develop and the degree to which the tumors have spread.
Almost all breast cancers are classified as adenocarcinomas, tumors that begin in glandular tissue. Breast adenocarcinomas generally originate either in ducts (ductal carcinomas) or in lobules (lobular carcinomas).
Noninvasive breast cancers
The most common noninvasive breast cancers are ductal carcinomas in situ. In situ is a term used to describe tumors that have not spread outside their original locations. Ductal carcinomas in situ are confined to the breast ducts. Almost all women diagnosed with this nonmalignant stage of breast cancer can be cured. Lobular carcinoma in situ is not usually technically classified as a breast cancer. This early grade of tumor involves abnormal cells that do not penetrate through the walls of the lobules. Although these growths are not life-threatening, women who have them are at a greater risk of developing breast cancer in another part of the same breast or in the other breast.
Invasive breast cancers: Approximately 80 percent of invasive breast cancers are invasive ductal carcinomas, tumors that have spread from the duct to the surrounding fatty tissue. Invasive lobular carcinomas, which start in the milk-producing glands and spread to other tissue, account for 10 to 15 percent of invasive breast cancers. These cancers are more difficult to detect using mammograms than ductal carcinomas.
Five percent of invasive breast cancers are medullary carcinomas, which are characterized by a distinct boundary marked by immune cells and by larger-sized cancer cells. The chance of survival associated with medullary carcinomas is higher than for other invasive breast cancers.
Other types of invasive breast cancer that occur less frequently include tubular carcinomas , inflammatory breast cancer , mucinous carcinoma (formed by mucus-producing cells), Paget's disease of the nipple, and phyllodes tumor (made of the breast's connective tissue).
Statistics
In 2005, approximately 212,930 cases of invasive breast cancer and 58,490 new cases of noninvasive breast cancer were estimated to be diagnosed in women.
40,410 women were expected to die from breast cancer in 2005.
About 1,690 cases of breast cancer diagnoses in men and 460 male breast cancer deaths were expected in 2005.
After increasing an average of 4 percent per year in the 1980s, breast cancer rates appear to be leveling off among white women.
Breast cancer mortality rates declined between the years of 1990 and 1997, with the most dramatic drops for both white and black women.
Over 75 percent of women diagnosed with breast cancer are age 50 or older.
Between 5 and 10 percent of breast cancers are inherited, and breast-cancer-susceptibility genes can be inherited from either parent.
The majority of women who develop breast cancer — around 80 percent — do not have a sister or mother with breast cancer.
With the exception of skin cancer, breast cancer is the most common cancer among women.
97.5 percent of women who are diagnosed with breast cancer in an early stage survive at least five years.
Among American women ages 30 to 69, black women have the highest breast cancer mortality rates. For women ages 70 and over, mortality rates are highest among white women.
Prevention
Women may lower their chances of developing breast cancer by making some healthy lifestyle choices. The steps outlined below can serve as a guide to healthy living that may aid in preventing not only breast cancer, but other cancers, as well.
Eat a well-balanced, low-fat diet full of fruits, vegetables and whole grains and maintain a healthy weight.
The relationship between fat intake and breast cancer is not completely understood by researchers. However, countries in which women have diets that are low in total fat, low in polyunsaturated fat and low in saturated fat have lower breast cancer rates than the
Maintaining a health weight is even more important after you have reached menopause, when estrogen is no longer produced in your ovaries. The adrenal glands convert other hormones into estrogen that is then stored in fat cells. The more fat cells — the greater amounts of estrogen, which is a major factor in post-menopausal breast cancer.
Limit alcohol consumption
Regular consumption of even a few drinks per week is associated with an increased risk of breast cancer in women. Women at high risk of breast cancer may want to consider not drinking any alcohol. If you do drink alcohol, do so in moderation. Studies have shown that post-menopausal women who drink less than one drink a day can increase the risk of dying of breast cancer up to 30 percent, compared to non-drinkers. Women who are pre-menopausal should not dismiss the link between alcohol and breast cancer — alcohol intake is a strong risk factor for the disease.
Exercise
Several studies suggest that moderate daily physical activity can lower your breast cancer risk. In addition to boosting your immune system, increasing your daily exercise helps prevent obesity and decreases estrogen levels — lowering your breast cancer risk. Another hormone called insulin growth factor or IGF is higher in obese women, especially those with fat around their middles. Too much of this hormone can increase risk for breast and colorectal cancer. Physical activity can reduce IGF levels.
If you are overweight, try to incorporate an exercise regimen and low-fat diet into your everyday routine. Becoming more physically fit will not only lower your risk of developing several cancers, but also will improve your overall health and emotional well-being.
Chemoprevention
Tamoxifen, an anti-estrogen medication that appears to block estrogen's effect on breast tissue, has been used for several years to reduce the risk of recurrence in localized breast cancer and as a treatment for advanced breast cancer. Studies have also show that women at high risk for breast cancer are less likely to develop the disease if they take tamoxifen. It is the only approved breast cancer chemopreventive and is prescribed for women at high-risk.
If you have several breast cancer risk factors and are interested in learning more about chemoprevention, speak with your health care professional. Risk, medical history and age are important topics to discuss when considering chemopreventive agents.
Raloxifene is another estrogen-blocker that has been shown to have protective effects against breast cancer. Scientists are currently conducting clinical trials to compare the effectiveness of raloxifene and tamoxifen in preventing breast cancer. Raloxifene is still being studied and is not yet recommended for use in reducing breast cancer unless you are participating in the clinical trials.
Aromatase inhibitors, drugs that block the production of small amounts of estrogen that post-menopausal women normally make, are also being studied as breast cancer preventative agents for post-menopausal women. New studies are also underway using other drugs, including studies that have found that women who take aspirin or non-steroidal anti-inflammatory drugs, such as ibuprofen, have a lower risk of breast cancer.
Preventive mastectomy
Healthy women with very high breast cancer risk may elect to have both breasts surgically removed in hopes of drastically lowering their chances of developing breast cancer. Women with the BRCA1 or BRCA2 genetic mutations (genetic testing is now available), previous history of breast cancer, strong family history or a history of lobular breast carcinoma might consider this type of operation after receiving a cancer risk assessment and educational counseling from their health care professional.
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