What is breast cancer?
Breast cancer is a malignancy that begins in breast cells. The most common type, invasive ductal carcinoma, starts in one of the breast's milk ducts and can then spread elsewhere in the breast, as well as potentially reaching other parts of the body through the blood or lymphatic systems. The American Cancer Society (ACS) reports that eight out of every 10 cases of breast cancer are invasive ductal carcinomas and estimates that 226,870 cases of breast cancer will be diagnosed in the United States in 2012 plus 63,300 new cases of carcinoma in situ (non-invasive breast cancer). Survival rates have been increasing - when detected at an early stage, the five-year relative rate of survival for localized breast cancer has increased from 72 percent to 96 percent over the past 60 years. Nonetheless, the ACS projects that in 2012 breast cancer will claim the lives of more than 39,000 women in the United States.
What are the symptoms of breast cancer?
The classic sign of breast cancer is a new lump in the breast or armpit. While most lumps don't turn out to be breast cancer, if you find one, be sure to see your doctor promptly. The following can also be signs of breast cancer:
- Thickening or swelling of part of the breast.
- Irritation or dimpling of breast skin.
- Redness or flaky skin in the nipple area or elsewhere on the breast.
- Pulling in (inversion) of the nipple or pain in the nipple area.
- Nipple discharge other than breast milk, including blood.
What are the causes?
Apart from mutations in certain genes, we don't know for sure what causes breast cancer. However, we do know a lot about the lifestyle factors that can increase the risk.
The greatest risks for breast cancer are being female and growing older (men can develop breast cancer, too, but only one percent of breast cancer cases occur in men.) Here are the major risk factors for women:
- Personal history of breast cancer.
- Family history of breast cancer. Some (but not all) of these cases stem from mutations in two genes, BRCA1 or BRCA2. Normally, these genes act as tumor suppressors that protect against breast cancer, but women can inherit copies of one of these genes containing mutations that promote development of the disease; if they do, the risk for breast cancer may be as high as 80 percent. It is estimated that between 5 and 10 percent of all cases of breast cancer stem from inherited mutations of BRCA1 or BRCA2. Rare mutations in other genes may influence breast cancer risk but not to the extent of BRCA1 and BRCA2.
- Giving birth after age 30: Breast cancer risk is elevated in women who have never had children or who first gave birth after age 30.
- Estrogen exposure: Throughout a woman's life, the less exposure she has to estrogen (the hormone that stimulates the growth and division of most breast cancer cells), the lower her risk of the disease. For this reason, women who begin to menstruate late and reach menopause early are at lower risk since estrogen levels are highest during a woman's reproductive years.
(For more about avoidable risk factors see the section below on the therapies Dr. Weil recommends.)
How is breast cancer diagnosed?
Annual mammograms for women over 40 have been key to successful early detection of breast cancer. However, many cases are found because a woman or her physician feels a lump in the breast that turns out to be cancer. Although monthly breast self-examinations are no longer recommended, all women should be familiar with the way their breasts normally feel so that they can recognize any changes that occur.
The evaluation of a breast mass begins with physical examination of the breasts, armpits, neck and chest area by a physician. If breast cancer is suspected, one or more of the following tests will be recommended:
- A mammogram to evaluate the breast lump;
- Breast ultrasound to determine whether the lump is solid or fluid-filled;
- An MRI to help better define the breast lump or evaluate an abnormal finding on a mammogram;
- A biopsy to remove cells from the lump for laboratory and microscopic analysis.
When a biopsy shows that cancer is present, it is important to test the cells removed during the procedure for receptors for the hormones estrogen and progesterone, which often feed the growth of breast cancer cells. When the cells have receptors for estrogen, the disease is described as ER (estrogen receptor) positive. When progesterone receptors are present, the disease is considered "PR-positive." As a general rule, estrogen receptor positive tumors are slower growing than those without receptors and are also more likely to respond to hormone therapy (see treatment section below). Most breast cancers (about two-thirds) have a receptor for either estrogen or progesterone.
When cancer is found, the following additional tests may be needed:
- A CT and / or bone scan to be sure the cancer has not spread
- PET scan (positron emission tomography), an imaging test that uses a radioactive substance (called a tracer) to identify areas of cancer that may have been missed by other studies.
- Sentinel lymph node biopsy, a test that involves the surgical removal of a regional lymph node to determine whether the cancer has spread beyond the breast.
Results of the tests described above enable doctors to "stage" the cancer - that is, to determine what they're dealing with in terms of the size of the tumor, and whether or not it has spread to lymph nodes or to other sites in the body. The most common system of classifying cancers is based on what is known as the T, N, and M stages. Here's an explanation of this system from the American Cancer Society:
- The letter T followed by a number from 0 to 4 describes the tumor's size and degree of spread to the skin or to the chest wall under the breast. Higher T numbers mean a larger tumor and/or wider spread to tissues near the breast.
- The letter N followed by a number from 0 to 3 indicates whether the cancer has spread to lymph nodes near the breast and, if so, how many lymph nodes are affected.
- The letter M followed by a 0 or 1 indicates whether the cancer has spread to distant organs - for example, the lungs or bones.
In addition to the information gathered via medical tests, studies have recently identified four genetic types of breast cancer. This new information may help direct and improve treatment:
- Luminal A and B: Two types of breast cancer originate in luminal cells lining the breast's milk ducts. Here, proteins on the cell surfaces reach out and seize estrogen, which promotes the growth of the tumors. The studies showed that patients with breast cancer described as luminal A had a good outlook, while those with luminal B had generally poorer outcomes. These findings may mean that patients with luminal A cancer might do well after initial breast cancer treatment with hormonal therapy to block estrogen from attaching to any remaining cancer cells, while those with luminal B will most likely require additional forms of treatment.
- Basal-like breast tumors: These tumors are sometimes called "triple negative" because the cancer cells have no receptors for the hormones estrogen, progestin and the protein HER2, each of which often promote breast cancer growth. The new studies found that these tumors are more similar genetically to ovarian cancer and a form of lung cancer than to other types of breast cancer. They account for about 10 percent of all breast cancers, tend to be aggressive and hard to treat, and are most common among young women, African-American women, and women with mutations in the breast cancer genes BRCA1 and BRCA2. (Most triple negative breast cancers are basal in nature, but not all basal-type breast cancers are triple negative). Here, the cancer cells resemble basal cells of the skin and sweat glands seen in the deepest layer of the skin. Because of their new-found genetic similarity to ovarian tumors, researchers have suggested that the basal-like breast cancers might be treated with the same drugs used against ovarian cancer.
- HER2 enriched cancer: Some breast cancers have cells that over-express a protein called HER2 (Human Epidermal Growth Factor 2) as a result of a genetic mutation. Today, women with this type of the disease are typically treated with the drug Herceptin, a monoclonal antibody that can kill HER2 positive cancer cells and has vastly improved the outlook for most of these patients. The new studies found that not all HER2 tumors are alike. Those the researchers described as "HER2 enriched" respond well when treated with Herceptin. But the studies found that the drug may not work so well for women with another type of HER2 tumor. A clinical trial is planned to explore the differences between ER2 tumors.
What is the conventional treatment?
In general, treatment for breast cancer relies on some combination of surgery, chemotherapy and radiation. Afterward, women may be advised to take additional drugs to reduce the risk of a recurrence. Here's a rundown:
- Surgery: This can mean a lumpectomy for early stage breast cancer to remove the malignant lump and some surrounding tissue in order to eliminate any cancer cells that may have spread locally beyond the lump itself. Lumpectomy preserves the breast and is equal to mastectomy (removing the entire breast) in terms of long-term survival for most patients with early breast cancer. More extensive surgery may be required with advanced disease.
- Chemotherapy: Usually a follow-up to surgery (adjuvant therapy), chemotherapy involves a course of drugs to destroy any cancer cells that may have spread beyond the breast. In some cases, chemotherapy may be recommended as a first line approach, known as neoadjuvant therapy, in an effort to shrink a tumor that may be inoperable so that there's a better chance that surgery will be successful; neoadjuvant therapy may also be recommended to shrink a tumor that could be removed by mastectomy to a size that will permit breast-conserving surgery (lumpectomy).
- Radiation: This is the use of high energy x-rays to destroy any cancer cells that may remain in the area of the lump after surgery.
- Hormonal therapy: Since most breast cancer growth and spread is fueled by estrogen, doctors often prescribe a course of hormonal therapy to follow surgery, chemotherapy and / or radiation. The idea here is to prevent estrogen from entering any remaining breast cancer cells and promoting their survival and spread. The anti-estrogen drug tamoxifen has been used for this purpose for more than 30 years. It prevents estrogen from binding to breast cancer cells by blocking receptors on those cells. Two other drugs that can be used for this purpose are raloxifene (Evista) and toremifene (Fareston®). A class of drugs called aromatase inhibitors (Aromasin) prevent production of estrogen out of other hormones and work as well as or better than tamoxifen to prevent recurrences.
- Targeted therapy: Also called biologic therapy, this approach employs anticancer drugs to block changes in cells that can lead to cancer. One of these drugs is trastuzumab (Herceptin) for women with HER2-positive breast cancer.
What therapies does Dr. Weil recommend?
Dr. Weil recommends that all women diagnosed with breast cancer seek treatment with a qualified and experienced breast surgeon, oncologist and radiation specialist. However, he emphasizes the need for the following lifestyle measures to reduce the risks of developing breast cancer in the first place and to help prevent recurrences after treatment:
- Maintain a healthy weight. Weight gain after age 18 to between the ages of 50 and 60, has been consistently associated with risk of breast cancer after menopause. When the ovaries stop producing hormones after menopause, fat cells produce most of the estrogen in the female body. The more fat tissue in a woman's body, the higher her estrogen levels are likely to be, and the higher her risk of breast cancer.
- Exercise. Regular physical activity can reduce the risks, possibly because it can lead to weight loss and decrease the amount of body fat, thereby reducing exposure to circulating estrogens produced by fat that could foster development of the disease.
- Reduce exposure to xenoestrogens. A large number of synthetic chemical compounds that we all encounter have estrogen-like activity. Among them: common pesticides, industrial pollutants and hormone residues in meat, poultry and dairy products. While evidence linking these hormones to breast cancer is conflicting, Dr. Weil recommends limiting exposure as much as possible. Choosing hormone-free dairy and animal products and organic produce is a good start.
- Avoid alcohol. A study reported in the November 2011 issue of the Journal of the American Medical Association found that the more a woman drinks, the higher her breast cancer risk. Data from a study including 108,986 nurses who were followed from 1980 to 2008 showed that having two or more alcoholic drinks daily increased a woman's risk of breast cancer by 1.5 times compared to women who never drank alcohol; for women who had one alcoholic drink per day, the risk was about 1.2 times higher than normal. Alcohol is believed to increase a woman's risk because it increases levels of estrogen and other hormones associated with hormone receptor positive breast cancer.
- Avoid long-term hormone replacement therapy (HRT). Data from the Women's Health Initiative (WHI) study of hormone replacement therapy that was halted ahead of schedule in 2004 showed an increased risk of breast cancer among women who took HRT, a combination of estrogen and progestin to slow post-menopausal bone loss and relieve menopausal symptoms. Follow up studies have shown that this increased risk continues for about 11 years after women stop taking the hormones. However, when the WHI study was stopped, women who were taking estrogen alone had a 23 percent reduced risk of breast cancer compared to those who took a placebo. Since then, studies have shown that the lower risk persisted for at least five years. (Estrogen replacement therapy (ERT) alone should only be prescribed for women who have had a hysterectomy - it presents a risk of endometrial cancer for women who still have a uterus. Adding progestin lowers this risk.) Until there are definitive data suggesting otherwise, Dr. Weil continues to recommend limiting use of HRT.
Nutrition and Supplements
- Choose fats wisely. Studies have shown that women with a higher intake of olive oil have less breast cancer. Omega-3 fats, found in cold-water fish (especially wild salmon and sardines), freshly ground flaxseed and walnuts have also been associated with inhibiting the growth of breast tumors. Consider taking 2 grams of a good fish oil supplement daily.
- Eat lots of vegetables and fruit. They contain cancer-protective phytochemicals, especially cruciferous vegetables such as broccoli, cauliflower, kale and watercress. Dr. Weil recommends eating 8 to 10 servings of vegetables and fruits a day.
- Eat less meat. Women who eat the most meat have a higher breast cancer risk than those who eat the least or none. If you eat meat, choose organic varieties to lessen exposure to residues of hormones used as growth promoters in cattle, and cook it less rather than more - a preference for well-done meat correlates with increased risk because carcinogenic compounds form as animal tissue is cooked at high temperatures.
- Use freshly ground flaxseed or other sources of fiber daily. Diets high in fiber seem to help reduce estrogen levels and promote appropriate weight loss, thereby reducing the risk of breast cancer. In addition, the lignans contained in flax may have a protective effect against breast cancer.
- Eat more soy. Although the isoflavones in soy have a mild estrogenic effect (they are able to bind to estrogen receptor sites in human tissue), soy foods contain many cancer-protective substances and also appear to possess anti-estrogenic effects. For this reason, and also because population studies have failed to show a relationship between soy consumption and increased risk of breast cancer, Dr. Weil recommends eating one serving of whole soy foods a day. If you have female children, he suggests startingthem on whole soy foods early. Regular, moderate consumption of whole soy foods early in life influences development of breast tissue in ways that appear to reduce risk.
- Drink green tea. Regular consumption of green tea has been linked to a lower incidence of many kinds of cancer.
- Take a multivitamin. Choose one that contains vitamin D and antioxidants, all of which have been linked to a reduced risk of breast cancer. Although your diet should be the primary source of most of your nutrients, a good daily supplement can help insure that your intake is adequate.
Dr. Weil also recommends the book Breast Cancer: Reduce Your Risk with Foods You Love (Penstokes Press, 2011), by Robert Pendergrast, M.D., who teaches at the Medical College of Georgia and is a graduate of the Fellowship at the University of Arizona's Center for Integrative Medicine. The book is a clear, scientifically validated compendium of what to eat, and what to avoid, in order to reduce your risk of breast cancer.
Updated by: Russell H. Greenfield, M.D. on October 15th, 2012