Research into the causes, prevention, and treatment of breast cancer is under way in many medical centers throughout the world.
Causes of breast cancer
Studies continue to uncover lifestyle factors and habits that alter breast cancer risk. Ongoing studies are looking at the effect of exercise, weight gain or loss, and diet on breast cancer risk.
Studies on the best use of genetic testing for BRCA1 and BRCA2 mutations continue at a rapid pace. Scientists are also exploring how common gene variations may affect breast cancer risk. Each gene variant has only a modest effect in risk (10 to 20%), but when taken together they may potentially have a large impact.
Potential causes of breast cancer in the environment have also received more attention in recent years. While much of the science on this topic is still in its earliest stages, this is an area of active research.
A large, long-term study funded by the National Institute of Environmental Health Sciences (NIEHS) is now being done to help find the causes of breast cancer. Known as the Sister Study, it has enrolled 50,000 women who have sisters with breast cancer. This study will follow these women for at least 10 years and collect information about genes, lifestyle, and environmental factors that may cause breast cancer. An offshoot of the Sister Study, the Two Sister Study, is designed to look at possible causes of early onset breast cancer. To find out more about these studies, call 1-877-4-SISTER (1-877-474-7837) or visit the Sister Study Web site (www.sisterstudy.org).
Chemoprevention
Results of several studies suggest that selective estrogen-receptor modulators (SERMs) like tamoxifen and raloxifene may lower breast cancer risk in women with certain breast cancer risk factors. But so far, many women are reluctant to take these medicines because they are concerned about possible side effects.
Newer studies are looking at whether aromatase inhibitors — drugs such as anastrozole, letrozole, and exemestane — can reduce the risk of developing breast cancer in post-menopausal women. These drugs are already being used as adjuvant hormone therapy to help prevent breast cancer recurrences, but none of them is approved for reducing breast cancer risk at this time. One of these drugs, exemestane, has recently been shown to lower the risk of invasive breast cancer by 65% in women at increased risk.
Fenretinide, a retinoid, is also being studied as a way to reduce the risk of breast cancer (retinoids are drugs related to vitamin A). In a small study, this drug reduced breast cancer risk as much as tamoxifen. Other drugs are also being studied to reduce the risk of breast cancer.
For more information, see our document, Medicines to Reduce Breast Cancer Risk.
New laboratory tests
Gene expression studies
One of the dilemmas with early-stage breast cancer is that doctors cannot always accurately predict which women have a higher risk of cancer coming back after treatment. That is why almost every woman, except for those with small tumors, receives some sort of adjuvant treatment after surgery. To try to better pick out who will best benefit from adjuvant therapy, researchers have looked at many aspects of breast cancers.
In recent years, scientists have been able to link certain patterns of genes with more aggressive cancers — those that tend to come back and spread to distant sites. Some lab tests based on these findings, such as the Oncotype DX and MammaPrint tests, are already available, although doctors are still trying to determine the best way to use them. These tests are explained in the section, "How is breast cancer diagnosed?" Other tests are being developed as well.
Circulating tumor cells
Researchers have found that in many women with breast cancer, cells may break away from the tumor and enter the blood. These circulating tumor cells can be detected with sensitive lab tests. These tests are not yet available for general use, but they may eventually be helpful in determining whether treatment (such as chemotherapy) is working in patients with metastatic breast cancer.
Newer imaging tests
Several newer imaging methods are now being studied for evaluating abnormalities that may be breast cancers.
Scintimammography (molecular breast imaging)
In scintimammography, a slightly radioactive tracer called technetium sestamibi is injected into a vein. The tracer attaches to breast cancer cells and is detected by a special camera.
This is a newer technique that is still being studied to see if it will be useful in finding breast cancers. Some radiologists believe it may helpful in looking at suspicious areas found by regular mammograms, but its exact role remains unclear. Current research is aimed at improving the technology and evaluating its use in specific situations such as in the dense breasts of younger women. Some early studies have suggested that it may be almost as accurate as more expensive magnetic resonance imaging (MRI) scans. This test, however, will not replace your usual screening mammogram.
Tomosynthesis (3D mammography)
This technology is basically an extension of a digital mammogram. For this test, the breast is compressed once and a machine takes many low-dose x-rays as it moves over the breast. The images taken can be combined into a 3-dimensional picture. Although this uses more radiation than most standard 2 view mammograms, it may allow doctors to see problem areas more clearly, lowering the chance that the patient will need to be called back for more imaging tests. A breast tomosynthesis machine was approved by the Food and Drug Administration (FDA) in 2011 for use in the US, but the role of this technology in screening and diagnosis is still not clear.
Several other imaging methods, including thermal imaging (thermography) are discussed in our document, Mammograms and Other Breast Imaging Procedures.
Computer-aided detection and diagnosis (CAD)
Computer-aided detection and diagnosis (CAD) was developed to help radiologists detect suspicious changes on mammograms. In this technique, computers help doctors identify abnormal areas on a mammogram by acting as a second set of eyes. This can be done with standard film mammograms or with digital mammograms. For standard mammograms, the film is fed into a machine which converts the image into a digital signal that is then analyzed by the computer.
Alternatively, the technology can be applied to a digital mammogram. The computer then displays the image on a video screen, with markers pointing to areas that the radiologist should check especially closely.
Although some doctors find CAD helpful, the results of 2, large studies found that it did not find more cancers or find cancers earlier. It did, however, increase the number of women who needed to come back for more tests and/or have breast biopsies. Whether CAD will continue to be used in the future is not clear.
Treatment
Oncoplastic surgery
Breast-conserving therapy (lumpectomy or partial mastectomy) can often be used for early-stage breast cancers. But in some women, it can result in breasts of different sizes and/or shapes. For larger tumors, it might not even be possible, and a mastectomy might be needed instead. Some doctors address this problem by combining cancer surgery and plastic surgery techniques, known as oncoplastic surgery. This typically involves reshaping the breast at the time of the initial breast-conserving surgery, and may mean operating on the other breast as well to make them more symmetrical. This approach is still fairly new, and not all doctors are comfortable with it.
Breast reconstruction surgery
The number of women with breast cancer choosing breast conservation therapy has been steadily increasing, but there are some women who, for medical or personal reasons, choose mastectomy. Some of them also choose to have reconstructive surgery to restore the breast's appearance.
Technical advances in microvascular surgery (reattaching blood vessels) have made free-flap procedures an option for breast reconstruction. For more information on the types of reconstructive surgery now available, see our document, Breast Reconstruction After Mastectomy.
For several years, concern over a possible link between breast implants and immune system diseases has discouraged some women from choosing implants as a method of breast reconstruction.
Recent studies have found that although implants can cause some side effects (such as firm or hard scar tissue formation), women with implants do not have any greater risk for immune system diseases than women who have not had this surgery. Similarly, the concern that breast implants increase the risk of breast cancer recurrence or formation of new cancers is not supported by current evidence.
Radiation therapy
For women who need radiation after breast-conserving surgery, newer techniques such as hypofractionated radiation or accelerated partial breast irradiation may be as effective while offering a more convenient way to receive it (as opposed to the standard daily radiation treatments that take several weeks to complete). These techniques are described in more detail in the section, "How is breast cancer treated?"
These techniques are being studied to see if they are as effective as standard radiation in helping prevent cancer recurrences.
New chemotherapy drugs
Advanced breast cancers are often hard to treat, so researchers are always looking for newer drugs.
A drug class has been developed that targets cancers caused by BRCA mutations. This class of drugs is called PARP inhibitors and they have shown promise in clinical trials treating breast, ovarian, and prostate cancers that had spread and were resistant to other treatments. Further studies are being done to see if this drug can help patients without BRCA mutations.
Targeted therapies
Targeted therapies are a group of newer drugs that specifically take advantage of gene changes in cells that cause cancer.
Drugs that target HER2: There are 2 drugs approved for use that target excess HER2 protein, trastuzumab (Herceptin) and lapatinib (Tykerb). Studies continue to see which of these is best for treating early breast cancer. Other drugs that target the HER2 protein are being tested in clinical trials, including TDM-1, pertuzumab and neratinib. Researchers are also looking at using a vaccine to target the HER2 protein.
Anti-angiogenesis drugs: In order for cancers to grow, blood vessels must develop to nourish the cancer cells. This process is called angiogenesis. Looking at angiogenesis in breast cancer specimens can help predict prognosis. Some studies have found that breast cancers surrounded by many new, small blood vessels are likely to be more aggressive. More research is needed to confirm this.
Bevacizumab (Avastin) is an example of anti-angiogenesis drug. Although bevacizumab turned out to not be very helpful in the treatment of breast cancer, this approach still may prove useful in breast cancer treatment. Several other anti-angiogenesis drugs are being tested in clinical trials.
Drugs that target EGFR: The epidermal growth factor receptor (EGFR) is another protein found in high amounts on the surfaces of some cancer cells. Some drugs that target EGFR, such as cetuximab (Erbitux®) and erlotinib (Tarceva®), are already used to treat other types of cancers, while other anti-EGFR drugs are still considered experimental. Studies are now under way to see if these drugs might be effective against breast cancers.
Other targeted drugs: Everolimus (Afinitor®) is a targeted therapy drug that is approved to treat kidney cancer. In one study, letrozole plus everolimus worked better than letrozole alone in shrinking breast tumors before surgery. More studies using this drug are planned.
Many other potential targets for new breast cancer drugs have been identified in recent years. Drugs based on these targets are now being studied, but most are still in the early stages of clinical trials.
Bisphosphonates
Bisphosphonates are drugs that are used to help strengthen and reduce the risk of fractures in bones that have been weakened by metastatic breast cancer. Examples include pamidronate (Aredia) and zoledronic acid (Zometa).
Some studies have suggested that zoledronic acid may help other systemic therapies, like hormone treatment and chemo) work better. In one study, the women getting zolendric acid with chemo had their tumors shrink more than the women treated with chemo alone. In other studies, giving zoledronic acid with other adjuvant treatment reduced the risk of the cancer coming back. Some more recent studies have not shown a benefit of giving this drug with adjuvant chemo. More studies are needed to determine if bisphosphonates should become part of standard therapy for early-stage breast cancer.
Denosumab
Denosumab (Xgeva, Prolia) can also be used to help strengthen and reduce the risk of fractures in bones that have been weakened by metastatic breast cancer. It is being studied to see if it can help adjuvant treatments work better.
Vitamin D
A recent study found that women with early-stage breast cancer who were vitamin D deficient were more likely to have their cancer recur in a distant part of the body and had a poorer outlook. More research is needed to confirm this finding, and it is not yet clear if taking vitamin D supplements would be helpful. Still, you may want to talk to your doctor about testing your vitamin D level to see if it is in the healthy range.
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