BREAST CANCER

Breast Cancer Pictures Slideshow: A Visual Guide to Breast Cancer

Reviewed by Varnada Karriem-Norwood, MD on Tuesday, September 27, 2011

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Breast Cancer Today

Breast cancer today is not what it was 20 years ago. Survival rates are climbing, thanks to greater awareness, more early detection, and advances in treatment. For roughly 200,000 Americans who are diagnosed with breast cancer each year, there are plenty of reasons to be hopeful.

Breast Cancer Symptoms

There are often no symptoms of breast cancer, but sometimes women may discover a breast problem on their own. Signs and symptoms to be aware of may include:

• A painless lump in the breast.
• Changes in breast size or shape.
• Swelling in the armpit.
• Nipple changes or discharge.

Breast pain can also be a symptom of cancer, but this is not common.

Signs of Inflammatory Breast Cancer

Inflammatory breast cancer is a rare, fast-growing type of cancer that often causes no distinct lump. Instead, breast skin may become thick, red, and may look pitted -- like an orange peel. The area may also feel warm or tender and have small bumps that look like a rash.

Breast Cancer & Mammograms

The earlier breast cancer is found, the easier it is to treat. And mammograms, X-rays of the breast, can detect tumors before they are large enough to feel. The American Cancer Society recommends yearly mammograms beginning at age 40 for women at average risk. While the U.S. Preventive Services Task Force recommends a screening mammogram every two years from age 50 to 74. It also notes that before age 50, each woman should check with a doctor to find out what screening schedule is right for her, considering the potential benefits and harms from screening.

Breast Ultrasound and MRI

Besides a mammogram, your doctor may order additional imaging with breast ultrasound. An ultrasound can help determine the presence of cysts, fluid-filled sacs that are not cancer. An MRI may be recommended along with a mammogram for routine screening in certain women who have a higher risk of breast cancer.

Breast Self-Exams

It was once widely recommended that women check their own breasts once a month. But studies suggest these breast self-exams play a very small role in finding cancer. The current thinking is that it's more important to know your breasts and be aware of any changes, rather than checking them on a regular schedule. If you want to do breast self-exams, be sure to go over the technique with your doctor.

What If You Find a Lump?

First, don't panic. Eighty percent of breast lumps are not cancerous. Lumps often turn out to be harmless cysts or tissue changes related to your menstrual cycle. But you should let your doctor know right away if you find anything unusual in your breast. If it is cancer, the earlier it's found the better. And if it's not, testing can give you peace of mind.

Breast Biopsy

The only sure way to determine whether a lump is cancer is to do a biopsy. This involves taking a tissue sample for further examination in the lab, sometimes through a small needle. Sometimes surgery is done to take part of or the entire lump for testing. The results will show whether the lump is cancer, and if so, what type. There are several forms of breast cancer, and treatments are carefully matched to the type of cancer.

Hormone-Sensitive Breast Cancer

Some types of breast cancer are fueled by the hormones estrogen or progesterone. A biopsy can reveal whether a tumor has receptors for estrogen (ER-positive) and/or progesterone (PR-positive). About two out of three breast cancers are hormone sensitive. There are several medications that keep the hormones from promoting further cancer growth.
The image shows a molecular model of an estrogen receptor.

HER2-Positive Breast Cancer

In about 20% of patients, breast cancer cells have too many receptors for a protein called HER2. This type of cancer is known as HER2-positive, and it tends to spread faster than other forms of breast cancer. It's important to determine whether a tumor is HER2-positive, because there are special treatments for this form of cancer.
A HER2-positive breast cancer cell is illustrated here, with abnormal growth signals shown in green.

Breast Cancer Stages

Once breast cancer has been diagnosed, the next step is to determine how big the tumor is and how far the cancer has spread. This process is called staging. Doctors use Stages 0-4 to describe whether cancer is localized to the breast, has invaded nearby lymph nodes, or has spread to other organs, such as the lungs. Knowing the stage and type of breast cancer will help your health care team formulate a treatment strategy.

Breast Cancer Survival Rates

The odds of surviving breast cancer are strongly tied to how early it is found. According to the American Cancer Society, 100% of women with Stage 1 breast cancer live at least five years, compared to women without cancer – and many women in this group remain cancer-free for good. The more advanced the cancer, the lower this figure becomes. By Stage 4, the five-year relative survival rate declines to 20%. But these rates can improve as more effective treatments are found.

Breast Cancer Surgery

There are many types of breast cancer surgery, from taking out the area around the lump (lumpectomy or breast-conservation surgery) to removing the entire breast (mastectomy.) It's best to discuss the pros and cons of each of these procedures with your doctor before deciding what's right for you.

Radiation Therapy for Breast Cancer

Radiation therapy uses high-energy rays to kill cancer cells. It may be used after breast cancer surgery to wipe out any cancer cells that remain. It can also be used along with chemotherapy for treatment of cancer that has spread to other parts of the body. Side effects can include fatigue and swelling or a sunburn-like feeling in the treated area.

Chemotherapy for Breast Cancer

Chemotherapy uses drugs to kill cancer cells anywhere in the body. The drugs are often given by IV, but are sometimes taken by mouth or shot. Chemotherapy may be done after surgery to lower the odds of the cancer coming back. In women with advanced breast cancer, chemotherapy can help control the cancer's growth. Side effects may include hair loss, nausea, fatigue, and a higher risk of infection.

Hormone Therapy for Breast Cancer

Hormone therapy is an effective treatment for women with ER-positive or PR-positive breast cancer. These are cancers that grow more rapidly in response to the hormones estrogen or progesterone. Hormone therapy can block this effect. It is most often used after breast cancer surgery to help keep the cancer from coming back. It may also be used to reduce the chance of breast cancer developing in women who are at high risk.

Targeted Drugs for Breast Cancer

Targeted therapies are newer drugs that target specific properties within cancer cells. For example, women with HER2-positive breast cancer have too much of a protein called HER2. Targeted therapies can stop this protein from promoting the growth of cancer cells. These drugs are often used in combination with chemotherapy. They tend to have milder side effects compared to chemotherapy.

Life After Diagnosis

There's no doubt that cancer is a life-changing experience. The treatments can wear you out. You may have trouble managing daily chores, work, or social outings. This can lead to feelings of isolation. It's crucial to reach out to friends and family for support. They may be able to go with you to treatments, help out with chores, or just remind you that you are not alone. Many people choose to join a support group -- either locally or online.

Breast Reconstruction

Many women who have a breast removed choose to undergo reconstructive surgery. This replaces the skin, nipple, and breast tissue that are lost during a mastectomy. Reconstruction can be done with a breast implant or with tissue from somewhere else in your body, such as the tummy. Some women opt to begin reconstruction at the same time as their mastectomy. But it's also possible to have reconstructive surgery months or years later.

Breast Forms

An alternative to breast reconstruction is to be fitted for a breast form. This is a breast-shaped prosthesis that fits inside your bra. Wearing a breast form allows you to have a balanced look when you are dressed -- without undergoing additional surgery. Like reconstructive surgery, breast forms are often covered by insurance.

Breast Cancer: Why Me?

The most obvious risk factor for breast cancer is being a woman. Men get the disease, too, but it is about 100 times more common in women. Other top risk factors include being over age 55 or having a close relative who has had the disease. But keep in mind that up to 80% of women with breast cancer have no family history of the illness.

Breast Cancer Genes

Some women have a very high risk of breast cancer because they inherited changes in certain genes. The genes most commonly involved in breast cancer are known as BRCA1 and BRCA2. Women with mutations in these genes have up to an 80 percent chance of getting breast cancer at some point in life. Other genes may be linked to breast cancer risk as well.

Risk Factors in Your Control

Being overweight, getting too little exercise, and drinking more than one alcoholic beverage per day can raise the risk of developing breast cancer. Birth control pills and some forms of postmenopausal hormone therapy can also boost your risk. But the risk goes back to normal after these medications are stopped. Among survivors, good lifestyle choices may be helpful. Recent studies suggest that physical activity may help lower the risk of a recurrence and it's a proven mood-booster.

Breast Cancer Research

Doctors continue to search for more effective and tolerable treatments for breast cancer. The funding for this research comes from many sources, including advocacy groups throughout the country. Many of the 2.5 million breast cancer survivors and their families choose to participate in walk-a-thons and other fundraising events. This links each individual fight against cancer into a common effort for progress.

Introduction to breast cancer prevention

For so many women, there is no more dreaded disease than breast cancer. Breast cancer elicits fears related to loss of body image and sexuality, surgery, and death. As is the case for most cancers, the exact cause of breast cancer is not clearly known. Furthermore, there is currently no cure for advanced disease, and there is no definitive way of preventing it.
Breast cancer also affects men. Male breast cancer accounts for about 1% of all breast cancers. Around 229,000 new cases of breast cancer are diagnosed each year in women in the U.S., while about 2,200 cases are diagnosed in men.
Our knowledge of how breast cancer develops is expanding rapidly. As a result, new medications are being developed to reduce the risk of breast cancer among those at high risk of contracting this disease. For the majority of women, lifestyle changes, a healthy diet, exercise, and weight reduction can also help reduce the chance of developing breast cancer. To date, the most important strategy in improving survival is still breast cancer screening and early detection. Breast cancer is the second leading cause of cancer deaths among women in the United States. The leading cause is lung cancer. One in every eight women in the United States develops breast cancer. The risk is even higher for women with previous breast cancer, those who have first-degree relatives with breast cancer, those with multiple family members with cancer, and those who have inherited "cancer genes."

What are the biological causes of breast cancer?

Breast cancer cells, like all cancers, initially develop because of defects in the genetic material deoxyribonucleic acid (DNA) of a single cell. The human body is composed of trillions of cells. Inside the inner core (nucleus) of each cell is our DNA located on chromosomes. Every human cell has two sets of 23 chromosomes. Each set is inherited from one parent. DNA exists as long, spiraled strands on these chromosomes. Different segments along the DNA strands contain information for various genes. Genes are blueprints that provide genetic instructions for the growth, development, and behavior of every cell. Human DNA is thought to contain approximately 23,000 genes. Most genes carry instructions for the types and the amount of proteins, enzymes, and other substances produced by the cells. Genes also govern the sizes and the shapes of the organs by controlling the rate of division of the cells within these organs. (During cell division, a cell makes a duplicate copy of its chromosomes and then divides into two cells.) Some genes restrict cell division and limit tissue growth.
Defects on the DNA strands can lead to gene coding errors, which in turn can cause diseases. When genes that normally restrict cell growth and divisions are absent or defective, the affected cells can divide and multiply without restraint. The cells that divide and multiply without restraint enlarge (forming a tumor) and can also invade adjacent tissues and organs. These cells can further break away and migrate to distant parts of the body in a process called metastasis. The ability to multiply without restraint, the tendency to invade other organs, and the ability to metastasize to other parts of the body are the key characteristics of cancers -- characteristics that are due to DNA defects.
The cancer-causing DNA defects can be acquired at birth (inherited) or may develop during adult life. The inherited DNA defects are present in every cell of the body. On the other hand, DNA defects that develop during adult life are confined to the descendants (products of cell divisions) of the single affected cell. Generally, inherited DNA defects have a greater tendency to cause cancers and cancers that occur earlier in life than DNA defects that develop during adult life.
Research has shown that 5%-10% of breast cancers are associated with mutations (defects) in two genes known as breast cancer-associated (BRCA) genes, BRCA1 and BRCA2. These genes function to prevent abnormal cell growth that could lead to cancer. Every cell in the body has two BRCA1 or BRCA2 genes, one inherited from each parent. A woman who has received one defective BRCA1 or BRCA2 gene from one parent and a healthy gene from the other is called a carrier of the defective BRCA gene. Even though only one healthy BRCA1 or BRCA2 gene is needed to help prevent cancerous growth of cells, the one remaining healthy BRCA gene is vulnerable to damage during adult life by environmental factors such as toxins, radiation, and other chemicals such as free radicals. Therefore, women bearing a defective BRCA1 or BRCA2 gene are at an increased risk of developing breast and ovarian cancers. Women carrying defective BRCA1 or BRCA2 genes also tend to develop these cancers earlier in life.
Other rare genetic mutations are also associated with an increased risk for the development of breast cancer, including mutations of the tumor suppressor gene p53, the CHEK-2 gene, and the ATM (ataxia-telangiectasia mutation) gene.
Since inherited DNA defects account for only 5%-10% of breast cancers, the majority of breast cancers are due to DNA damages that develop during adult life. Environmental factors that can cause DNA damage include free radicals, chemicals, radiation, and certain toxins. But even among individuals without inherited cancer-causing DNA defects, their vulnerability to DNA damage, their ability to repair DNA damage, and their ability to destroy cells with DNA damage, are likely to be genetically inherited. This is probably why the risk of cancer is higher among first-degree relatives of breast cancer patients, even among families that do not carry the defective BRCA1 and BRCA2 tumor-suppressing genes.
Some of the errors in the normal control mechanisms allow the accumulation of additional errors in other parts of the system. These errors may lead to gene silencing of critical control genes or the overactivity of other growth-stimulating genes by activation of promoter sites adjacent to these otherwise normal genes.
Other substances such as estrogen (a female hormone) and certain fatty acids may also increase the risk of breast cancer by stimulating the growth and division of cells of the breast tissue.

What is the importance of early breast cancer detection?

The various types of cancers behave differently, with distinct rates of growth and patterns of spreading (metastasis) to other areas of the body. Some cancers are "favorable" and treatable, while others are so aggressive and malignant that almost nothing in modern medicine's arsenal can help.
Compared to other cancers, breast cancer is on the more treatable end of the spectrum if diagnosed early. It is considered a "favorable" cancer because it can be detected early by breast examination or by mammography. Pancreatic cancer, for example, is on the lethal end of the spectrum of cancers. Pancreatic cancer is often difficult to detect until it is very far advanced.
Studies have clearly shown that the smaller the size of the breast cancer when detected, the better the chance of a surgical cure and long-term survival. The likelihood of a cure is also higher if the cancer is removed before it has spread to lymph nodes and other organs such as the lungs, liver, bones, and brain.
Currently, mammography and breast examinations serve as the foundation for screening for breast cancer. It is extremely important for a woman to have regular breast examinations as well as mammograms to detect early breast cancer.

What are the advantages and limitations of mammography?

Mammography is an X-ray examination of the breast that has the ability to detect a cancer in the breast when it is quite small, long before it may be felt by breast examination. Approximately 85%-90% of all breast cancers are detectable by mammography. Early detection by mammography has reduced the mortality rate from breast cancer by 20%-30% in women over 50 years of age.
However, some 10%-15% of breast cancers are not visible on mammography but can be felt on physical examination of the breast. Therefore, a normal mammogram does not exclude the possibility of breast cancer. Breast examination by your health care professional by palpation and visual inspection is also important. During a routine physical checkup, a doctor can conduct an examination of the breast.

How frequently should women undergo mammography and breast examinations?

The American Cancer Society (ACS) recommends a baseline mammogram for all women by age 40 and annual mammograms for women 40 and older for as long as they are in good health.
In women with "lumpy breasts" or breast symptoms, and also in women with a high risk of developing breast cancer, sometimes a baseline mammogram at 35 years of age is recommended. This recommendation is somewhat controversial, and there are other viewpoints.
However, the U.S. Preventive Services Task Force (USPSTF) issued new breast cancer screening guidelines in 2009, which recommend against routine mammography screening for women before 50 years of age and suggests that screening end at 74 years of age.
The new USPSTF recommendations are in opposition to other existing breast cancer screening guidelines from organizations such as the American Cancer Society as described above. The USPSTF guidelines also recommend changing the screening interval from one year to two years and suggest that women 40 to 49 years old who are at high risk for breast cancer consult with their doctor regarding the time to begin regular screening mammography.
It is important for women who are concerned about when to begin mammography to discuss the situation with their health care professional. He or she can help you make an informed decision about breast cancer screening that is appropriate for your individual situation.
Mammograms and young women
There is a special issue regarding mammograms in young women. Since young women have dense glandular breast tissue, routine mammograms have difficulty "seeing through" the dense breast tissue. Therefore mammograms may not be able to detect cancer in the breast because the dense breast tissue around the cancer obscures it. However, this problem can be partly offset by the use of special breast ultrasound, which is now an extremely important additional imaging technique used to supplement mammography in difficult cases. Ultrasound can make visible a lump hidden within dense breast tissue. It may also detect lumps and early breast cancers when mammograms fail to identify a problem. Ultrasound can also help doctors locate specific areas in the breast for biopsy (obtain small samples of tissue to study under a microscope). Sometimes doctors also suggest the use of magnetic resonance imaging (MRI) screening (see below) in younger women with dense breast tissue.
Magnetic resonance imaging (MRI) scanning
Recent research has shown that MRI scanning may be a useful screening tool for breast cancer in certain high-risk populations. In 2004, a team of Dutch researchers published a study of over 1,900 women at high risk for breast cancer in the New England Journal of Medicine. These women underwent breast cancer screening that included physical exams every six months along with yearly mammograms and MRI scans of the breasts. While conventional mammography did detect many cancers at an early stage, some tumors were identified by MRI that were not detected by mammography. Overall, MRI led to the identification of 32 tumors, of which 22 were not seen on the corresponding mammogram. Likewise, some tumors appeared on mammograms that were not visible on the MRI scan. Mammography detected a total of 18 tumors, of which eight were not identified by MRI.
The routine use of MRI, however, has many limitations. While it enabled the detection of some tumors in high-risk women, it also detected more noncancerous lesions (false-positives), which lead to many more follow-up examinations and potentially unnecessary medical procedures. In fact, MRI led to twice as many unnecessary examinations and three times as many unneeded surgical biopsies of the breast than screening by mammography alone. MRI is also approximately 10 times more costly (average cost $1000-$1500) than mammography.
Because of these limitations, experts believe that screening with MRI is impractical for women who do not have an elevated risk of developing breast cancer. However, its benefits appear to outweigh its limitations in certain high-risk populations.
In March 2007, the American Cancer Society Breast Cancer Advisory Group issued breast-cancer-screening recommendations that include MRI scanning along with mammography for women 30-69 years of age who are considered to have an estimated lifetime risk of developing breast cancer of 20%-25%.
Adding a yearly breast MRI was recommended for women who

• have a BRCA1 or BRCA2 mutation, indicative of a strong inherited risk of breast cancer;
• have a first-degree relative with a BRCA1 or BRCA2 mutation but have not been tested for the mutation;
• received chest radiation -- to treat Hodgkin's disease or other cancers, for example -- between 10 and 30 years of age.

The guidelines state that there is at present insufficient evidence to recommend the use of routine MRI screening in women with other risk factors, including a personal history of breast cancer, a history of carcinoma in situ or atypical hyperplasia, or dense breast tissue that makes the interpretation of mammograms difficult. Women with these risk factors may want to discuss their screening program with their physician to better determine whether MRI may be useful in their own case.
It is important to note that MRI should not be considered a substitute for regular mammography, and mammography is the only screening tool for which a reduction in mortality (death rate) from breast cancer has been proved.
Breast self-examination and breast examinations by your doctor
Both the American Cancer Society and the USPSTF do not call for regular self-examination of the breasts in their guidelines. The ACS states that breast self-exam is optional, while the USPSTF states that doctors should not teach women to do breast self-examination. The ACS further recommends a clinical breast exam (CBE) by a health care professional about every three years for women in their 20s and 30s and every year for women 40 years of age and over.

How helpful are BRCA1 and BRCA2 genetic tests in identifying women at risk?

In special circumstances, genetic tests can be very helpful both in identifying exceptionally high-risk patients and reducing the level of concern for others. We also now know that the presence of one of these genetic defects does not cause cancer in every patient. The cancers that do occur may also behave somewhat differently than non-BRCA-associated tumors. There is some evidence that they have a better outcome.
Before genetic tests are conducted, individuals being tested must have thorough counseling. A clear understanding of the limitations of the tests and the problems they may pose must precede the testing. The patient must know the meaning of the possible results, whichever way they may turn out, before testing. They should also have settled on a plan for each possible outcome of the test results. Often, the best way to evaluate a potential genetic risk is to test a relative who has already been diagnosed with breast cancer. If the relative's genetic testing (which must cover a large number of possible mutations) proves negative, then there is no need to perform genetic testing on the concerned individual. But the concerned individual should still undergo close monitoring with breast examinations and mammograms. If the test is positive on the relative, then that specific mutation is the only one that needs to be checked in the concerned individual and the other family members.

What is the link between estrogen and breast cancer?

Estrogen is a female hormone that is produced by the ovaries. During the reproductive years, a woman's body is exposed to high levels of estrogen. After menopause, the production of estrogen by the ovaries decreases. Estrogen is sometimes prescribed to treat some of the problems often associated with menopause, such as hot flashes, night sweats, sleeplessness, and vaginal dryness. Estrogen has the additional benefit of prevention of bone thinning (osteoporosis). However, results from a large clinical trial of postmenopausal women receiving hormone therapy (HT) released in 2002 showed that the overall risks of estrogen plus progestin therapy outweighed the benefits of hormone therapy. Combined hormone therapy with estrogen and progestin was shown to increase the risk of heart disease, stroke, and blood clots.
High levels of estrogen over long periods also increase the risk of developing breast and uterine cancers. Estrogen stimulates the cells of the breast and the uterine lining to grow and divide. Breast cells that are actively dividing are believed to have a greater chance of DNA damage as well as a higher number of cells that already have DNA damage. A higher number of cells with DNA damage elevate the risk of cancer development.
Women who have an early onset of their menstrual period (or menses) and late menopause are more likely to develop breast cancer than women with late menses onset and early menopause. This difference is believed to be attributable to the longer period of estrogen exposure in the first group.

Are there other breast cancer prevention measures?

Antioxidants
Antioxidants are chemicals that prevent a type of chemical reaction called oxidation. Oxidation is a major source of free radical formation. Antioxidants also mop up the free radicals that are formed.
Free radicals are electrically charged chemicals that can attack and damage proteins and DNA, thereby altering genetic information. If enough damage occurs to the DNA segments of a cell that controls cell division and growth, cancer can develop from that single cell. Free radicals can be formed by the normal metabolic activity in the body.
Free radicals also occur when cells are exposed to radiation. The body is regularly exposed to low levels of radiation in the atmosphere. The body also receives radiation during mammography and other X-ray tests. Theoretically, these low levels of radiation can lead to the formation of free radicals. (The amount of radiation in the atmosphere and in carefully performed X-rays tests is generally considered safe.)
Fortunately, a healthy body is well equipped to destroy free radicals and prevent cells with damaged DNA from becoming cancerous. The body is capable of quickly recognizing and destroying free radicals. For example, the body has an enzyme called superoxide dismutase that regularly cleans up free radicals and prevents them from damaging cells and proteins. The body can repair DNA damage caused by radiation or free radicals. The body is also capable of quickly destroying cells that have irreparable DNA damage to prevent them from turning cancerous. The immune system also seeks out cells with DNA damage and destroys them.
Naturally occurring antioxidants include beta carotene, vitamin E, and vitamin C. Fruits and vegetables are safe and rich sources of antioxidants. A somewhat controversial substance is caffeine. In several laboratory studies, caffeine acted like an antioxidant that cleans up free radicals. At present, there is no evidence that caffeine or coffee affects breast cancer risk. Also, some caffeine-containing substances, such as tea, have apparently been shown to decrease cancer risks.
Dietary fats
Early epidemiological studies suggested that high-fat diets might be associated with increased risks of breast cancer. But this relationship has not been confirmed, and results of studies have been mixed. Furthermore, it is clear that some fats may be protective rather than harmful. There are, however, some theoretical concerns about eating overcooked meats and fats.
Diet and lifestyle measures to reduce breast cancer risk
Theoretically, there are dietary and lifestyle measures that can decrease free-radical formation and reduce the risk of developing breast and other types of cancer. These measures include

• diets rich in vegetables and fruits;
• diets low in fats, and red and overcooked meats;
• reasonable intake of antioxidants, such as vitamins E and C;
• regular exercise and weight reduction;
• avoiding cigarettes.

Evidence that these measures reduce the chances of developing breast cancer is largely based on epidemiological data. Epidemiological evidence is derived from comparing two large populations with similar characteristics that have different diets or levels of exercise. Epidemiological evidence can only be suggestive, not conclusive. In fact, concrete proof that diet and exercise actually reduce the risk of developing breast cancer will be difficult to attain.
When firm scientific data is lacking and is unlikely to be available for the foreseeable future, the doctor has to weigh the risks of his/her recommendations against the potential benefits. Long-term risk and benefit considerations are especially important in advising young, healthy women about preventing a disease that they may or may not develop.
In the case of diets low in fat and overcooked meats, diets high in vegetables and fruits, avoiding smoking, and regular exercise, there is enough known benefit and very little known risk, which makes it easy for doctors to recommend them to their patients.
Doctors are also comfortable with recommending one multivitamin a day. However, there is no clinical evidence that taking megadoses of vitamins are of any benefit. Megadoses of certain vitamins can have adverse side effects.
Exercise
There is epidemiological data which show that women who exercise regularly have a lower incidence of breast cancer than women who do not exercise. The reason for such a benefit is unknown, but it may be related to the fact that obese individuals have higher levels of estrogen in the body than nonobese people. The higher levels of estrogen may increase the risk of breast cancer in obese women.

Conclusion

There are two important aspects in breast cancer prevention: early detection and risk reduction. Screening may identify early noninvasive cancers and allow treatment before they become invasive or identify invasive cancers at an early treatable stage. But screening does not, per se, prevent cancer. Breast cancer prevention really must be understood as risk reduction. In extremely high-risk patients, such as those who have BRCA mutations, risk reduction may involve prophylactic surgical removal of the breasts and ovaries. For the average patient, lifestyle modifications (diet, exercise, weight loss, etc.) may be easily recommended and have many other benefits. For patients who have an increased risk based on other factors, the use of hormone-blocking agents, in addition to the usual lifestyle recommendations, may also be considered.

SOURCE:medicinenet.com