Research into the causes, prevention, and treatment of breast cancer is under way in many medical centers throughout the world. Our document, Breast Cancer (in women) contains more information on advances in treatment because almost all breast cancer clinical trials and research are done in women.
Causes of breast cancer and breast cancer prevention
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. Some studies have found that men with mutations in these genes may be more likely to develop some other cancers, including prostate cancer, stomach cancer, pancreas cancer, and melanoma. The risks for these cancers will be further defined in future studies.
Other genes that contribute to breast cancer risk are also being identified. 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 possibly have a large impact.
A large ongoing study of causes of male breast cancer has recently identified several genetic variations associated with breast cancer risk. It reveals that the effect of these genetic variations on risk is different for men and women. This suggests differences in the biology of breast cancer in men and women. Work is ongoing to further evaluate these differences.
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.
New laboratory tests
Gene expression studies
One of the problems with early stage breast cancer is that doctors cannot always accurately predict who has a higher risk of the cancer coming back after treatment. That is why almost everyone, except for those with small tumors, receives some sort of adjuvant treatment after surgery. To try to better pick out who will need 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 breast cancers in women -- 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. It is not yet clear how useful these tests might be in men. For more information, see the separate American Cancer Society document, Breast Cancer.
Circulating tumor cells
Researchers have found that in many breast cancers, 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 help find out if a treatment (such as chemotherapy) is working or to detect cancer recurrence after treatment.
Treatment
Radiation therapy
For men who need radiation after breast-conserving surgery, newer techniques 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).
Hypofractionated radiation: Doctors are comparing giving larger daily doses of radiation over fewer days to the standard radiation schedule. Studies in women have shown that, giving radiation over 3 weeks seems to be about as effective as the standard 5-week course. Other studies have looked at giving even larger daily doses over an even shorter time, such as a week. But again, these studies have included few, if any, men, so it isn’t clear how helpful these schedules will be in treating men with breast cancer.
Chemotherapy
Because advanced breast cancers are often hard to treat, researchers are looking for newer drugs.
A drug has been developed that targets cancers caused by BRCA mutations. It is in a class of drugs called PARP inhibitors and is called olaparib. It was successful in treating breast, ovarian, and prostate cancers that had spread and were resistant to other treatments. Further studies are under way 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: Two drugs that target excess HER2 protein, trastuzumab (Herceptin) and lapatinib (Tykerb) are approved for use. 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 anti-angiogenesis drug that once showed promise in the treatment of metastatic breast cancer. 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 being done to see if these drugs might be effective against some types of breast cancer.
Other targeted drugs: Many other potential targets for new breast cancer drugs have been identified in recent years. Drugs based on these targets are now being studied, although 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 (such as hormone treatment and chemo) work better. In one study, the patients getting zoledronic acid with chemo had their tumors shrink more than those 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) is another drug that can be used to help strengthen and reduce the risk of fractures in bones that have been weakened by metastatic breast cancer. Studies to see if it can help adjuvant treatments work better are going on now.
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