Findings from a recent study conducted by researchers at the University of Washington are providing new insights into the future treatment of breast cancer.
The study is the first comprehensive genetic analysis of breast cancer, and was part of a large federal project known as the Cancer Genome Atlas, which was recently published in the science journal, Nature.
"Breast cancer cells start out as normal body cells, but these cells begin to grow out of control because of an abnormal gene," explained Oncologist Zoraida Mendez, M.D. "Researchers in the study looked closely for genetic changes in this process, such as how do breast cancer genes mutate and if there are specific patterns or characteristics related to these changes.
"The study focused on the most common types of breast cancer and on breast cancers that hadn't yet metastasized or spread to other parts of the body. What the investigators found is that most breast cancer tumors are caused by changes or mutations in certain genes. During the study, researchers analyzed tumors in 825 patients and found that most tumors are caused by mutations in approximately 30 to 50 specific genes. In addition, some of these genetic changes share common characteristics with other types of cancer that occur elsewhere in the body."
Four Types of Breast Cancer
The results of the cancer study identified four different types of breast cancer, each with unique genetic traits: luminal A and B cancers, HER2-enriched cancers, and basal-like cancers, which resemble the basal cells of the skin and sweat glands. Each of these types of breast cancer also has different sub-types that share genetic characteristics with some other types of cancers occurring in the body. For example, the researchers found that one form of breast cancer looks similar to a type of ovarian cancer, so the hope is that potential treatments for ovarian cancer could also work for these breast cancer patients.
New Treatment Perspectives
"Based on this genetic mapping, new treatments may be developed that can target specific genetic characteristics of the individual tumors," Dr. Mendez added. "The findings are expected to lead to new drug treatments that have already been approved for use in treating cancers in other parts of the body, which share the same types of genetic mutations."
Based on the findings, researchers now know that only clinical trials will reveal which tumors respond to certain drugs and which don't. These results could provide greater understanding of the cancer itself and give more clues in the search for alternate treatments.
According to study researcher Matthew Ellis, a Washington University professor of medicine, "There's types of therapies now for melanoma and lung cancer and colon cancer and leukemia, and we see subsets of breast cancer that have genetic relationships with these other forms of cancerSo can we reach across and grab those drugs approved for other purposes and re-purpose them for breast cancer?"
Scientists hope to develop more efficient treatments for breast cancer based on the genomes studied. But because there are so many different ways a breast cancer cell can mutate, there may need to be numerous drug studies and clinical trials performed to focus on the different genetic changes.
"While the results of the study represent major progress in breast cancer research, most people will have to wait years for the results of the clinical trials," said Dr. Mendez. "However, when these are completed, scientists will have more evidence on whether drugs that block genetic mutations can actually be used to effectively kill certain cancers."
Breast cancer is second only to lung cancer as the leading cause of cancer death among women in the U.S. "Early detection and effective treatment can reduce the number of women who die from breast cancer," concluded Dr. Mendez. "New methods of prevention also continue to be studied to provide more information in the fight against this disease."
Diet and Lifestyle: Diet continues to be studied as a risk factor for breast cancer. Studies show that in populations that consume a high-fat diet, women are more likely to die of breast cancer than women in populations that consume a low-fat diet.
Exercise, especially in young women, is under investigation as a tool that may decrease hormone levels and contribute to a decreased breast cancer risk. Breast feeding has also been linked to a decrease in a woman's risk of breast cancer. In addition, postmenopausal weight gain, especially after natural menopause and/or after age 60, may increase breast cancer risk.
Alcohol: Drinking alcohol may be linked to increased breast cancer risk. The more alcohol a woman drinks, the more her risk of breast cancer may increase, compared to a woman who drinks no alcohol. In addition, a diet rich in beta-carotene, folate, and vitamins A and C may reverse the higher risk of breast cancer linked to alcohol use.
Mammograms: Mammograms don't prevent breast cancer, but they can save lives by finding breast cancer as early as possible. For example, mammograms have been shown to lower the risk of dying from breast cancer by 35% in women over the age of 50. The National Cancer Institute, the American Cancer Society, and the American College of Radiology now recommend annual mammograms for women over 40.
Zoraida Mendez, M.D., is an oncologist affiliated with Salem Community Hospital's medical staff.