Elsevier Global Medical News. 2009 Oct 19, S Boschert
SAN FRANCISCO (EGMN) - The estimated 10-year risk for developing cardiovascular disease was at least as great as the risk of having a breast cancer recurrence in 78% of 242 postmenopausal women who were treated with an aromatase inhibitor for early-stage, hormone receptor-positive breast cancer.
Clinicians should consider the effects of various breast cancer therapies on other potential health problems, such as cardiovascular disease, when choosing cancer treatment, Dr. Aditya Bardia said at a breast cancer symposium sponsored by the American Society of Clinical Oncology, where he presented the finding.
With more women surviving breast cancer, these considerations take on growing importance, said Dr. Bardia of Johns Hopkins University, Baltimore. In 2009, an estimated 182,460 U.S. women will be diagnosed with breast cancers, with 42% of new breast cancers in women older than 65 years.
Cardiovascular disease is the leading cause of death in U.S. women. One previous study found an association between aromatase inhibitor therapy and cardiovascular risk, but other studies have reported no such association, he noted.
Dr. Bardia and his associates analyzed data on a subset of women from a randomized study that was designed primarily to compare two aromatase inhibitors - exemestane (Aromasin) and letrozole (Femara) - in 2 years of treatment either as first-line breast cancer therapy or after 2-5 years of tamoxifen therapy. All women were postmenopausal and had stage 0-III HR-positive breast cancer.
The investigators used the modified Framingham score at study enrollment to estimate the risk of developing a serious cardiovascular disease event (heart failure, coronary heart disease, stroke, or peripheral vascular disease) over the next 10 years. The scoring tool also was used to calculate each woman's "heart age" at baseline, a composite end point representing multiple risk factors in addition to biological age. They used Adjuvant! Online, a validated risk-assessment tool, to estimate the 10-year risk of breast cancer recurrence.
The 10-year risk for breast cancer recurrence was low (less than a 10% chance) in 42% of patients, moderate (10%-25% risk) in 55%, and high (greater than 25% chance) in 3%. In all, 36% of patients had a low risk for a serious cardiovascular disease event over the next 10 years, 52% had a moderate risk, and 12% were at high risk, Dr. Bardia reported.
The cardiovascular disease risk was equal to the cancer recurrence risk in 43% of patients and higher than the cancer risk in 35%, with the other 22% having lower risk for cardiovascular disease than for cancer.
Several factors identified women who were more likely to be at greater risk for cardiovascular disease than for breast cancer recurrence, Dr. Bardia said. The likelihood of greater cardiovascular risk was 16 times higher in women with a "heart age" greater than 65 years, compared with "younger" hearts. It was six times higher in those with breast tumors sized less than 2 cm, compared with larger tumors, and five times higher in patients with stage I breast disease, compared with those at stage II or III.
Two factors - having grade 1 or 2 breast disease instead of grade 3, and having lymph node-negative cancer instead of positive nodes - each tripled the likelihood that the cardiovascular risk would be greater than the cancer recurrence risk.
The findings need to be validated by studying other data sets, particularly ones that include outcomes data, Dr. Bardia said. Clinicians should consider educating postmenopausal breast cancer survivors about the importance of cardiovascular health, and there may be a need for interventions that modulate risks for both breast cancer and cardiovascular disease, he added.
Patient and tumor characteristics did not differ significantly between the risk-stratified groups.
The study was funded by the National Institutes of Health, Pfizer Inc. (which markets exemestane), and Novartis (which markets letrozole). Dr. Bardia also has received research funding from AstraZeneca and Eli Lilly and Co.
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