SAN ANTONIO -- Exemestane steadily lowered levels of "good" cholesterol in women taking the agent as part of a breast cancer prevention study, say researchers at Georgetown Lombardi Comprehensive Cancer Center. Exemestane, an aromatase inhibitor used to treat estrogen receptor-positive breast cancer, is being tested to prevent breast cancer in women at an increased risk of developing the disease.
Georgetown researchers say their findings, presented at the 2011 CTRC-AACR San Antonio Breast Cancer Symposium (SABCS), suggest that the effect this agent has on blood lipids may prove to be significant for women at high risk for heart disease due to elevated blood cholesterol, although no such effects have been seen yet in patients studied over two years of treatment.
There are two types of cholesterol transported in our blood—HDL and LDL. HDL cholesterol is known as "good" cholesterol, because high levels of it protect against heart attack. LDL cholesterol is known as "bad" cholesterol because it can buildup in the inner walls of the arteries that feed the heart and brain, and lead to atherosclerosis.
"Lower levels of the HDL, the good cholesterol, have been shown to increase the risk of heart attack and stroke. While we found that exemestane lowers good cholesterol levels, the clinical significance of this decrease is unknown," says a study investigator, Margaret Gatti-Mays, M.D. an intern in internal medicine at Georgetown.
The results come from a phase II multi-institutional study of women at increased risk for breast cancer that evaluated the safety and efficacy of exemestane over two years of therapy. The findings, from 31 patients, showed that the absolute change from the baseline HDL level at 3, 12, and 24 months were -8.0 mg/dL, -8.5 mg/dL, and -9.9 mg/dL, respectively. The rest of the lipid panel, including LDL (the bad cholesterol) was relatively unchanged.
"It is notable that both women taking and not taking lipid-lowering medication had decreases in HDL," Gatti-Mays says.
"Lower HDL levels are associated with an increased risk of heart disease, so if a patient has a low HDL level, exemestane may not be the best choice as a breast cancer prevention agent," says the study's senior investigator, Jennifer Eng-Wong, M.D., senior medical director of the Capital Breast Care Center at Georgetown Lombardi Comprehensive Cancer Center.
She adds that other anti-estrogen therapies designed to prevent breast cancer don't appear to lower HDL. "Less data is available on anastrozole and letrozole, which are other aromatase inhibitors, but they do not appear to lower HDL. Conversely, tamoxifen has an overall favorable effect on cholesterol."
"Exemestane has been shown to be an effective therapy in the prevention of breast cancer in postmenopausal women who have an increased risk of developing it. This study adds information that will help individualize care for these women though larger studies are needed to more fully evaluate the impact of exemestane on cholesterol and cardiovascular health," says Gatti-Mays.
The research was conducted at Georgetown and the National Cancer Institute (NCI), and was supported by both institutions, as well as the National Institutes of Health, and Pfizer Inc. (which supplied exemestane). (OVER)
A recipient of the ACCR Scholar-in-Training Award, Gatti-Mays' travel to the SABCS conference was funded by this award which is supported by Susan G. Komen for the Cure. She reports no personal financial interests related to the study.
The 2011 CTRC-AACR San Antonio Breast Cancer Symposium is presented by the Cancer Therapy & Research Center at UT Health Science Center San Antonio, the American Association for Cancer Research, and Baylor College of Medicine.
About Georgetown Lombardi Comprehensive Cancer Center
Georgetown Lombardi Comprehensive Cancer Center, part of Georgetown University Medical Center and Georgetown University Hospital, seeks to improve the diagnosis, treatment, and prevention of cancer through innovative basic and clinical research, patient care, community education and outreach, and the training of cancer specialists of the future. Georgetown Lombardi is one of only 40 comprehensive cancer centers in the nation, as designated by the National Cancer Institute, and the only one in the Washington, DC, area. For more information, go to http://lombardi.georgetown.edu.
About Georgetown University Medical Center
Georgetown University Medical Center is an internationally recognized academic medical center with a three-part mission of research, teaching and patient care (through MedStar Health). GUMC's mission is carried out with a strong emphasis on public service and a dedication to the Catholic, Jesuit principle of cura personalis -- or "care of the whole person." The Medical Center includes the School of Medicine and the School of Nursing & Health Studies, both nationally ranked; Georgetown Lombardi Comprehensive Cancer Center, designated as a comprehensive cancer center by the National Cancer Institute; and the Biomedical Graduate Research Organization (BGRO), which accounts for the majority of externally funded research at GUMC including a Clinical Translation and Science Award from the National Institutes of Health. In fiscal year 2010-11, GUMC accounted for 85 percent of the university's sponsored research funding.