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Now exclusively online, access the latest SROA Radiation Oncology News for Administrators publication by clicking on this link.
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Study Analyzes the Effects of IMRT and IGRT on the Heart Following Treatment for Left-sided Breast Cancer
June 13, 2011
A Brazilian research team found that both IMRT and IGRT considerably decreased the dose to the heart during treatment for left-sided breast cancer, according to an abstract of a journal article released during the American Society of Clinical Oncology (ASCO) meeting in early June.
M.L. Reisner and colleagues designed a small study involving 10 women with breast cancer to determine how IMRT and IGRT affected substructures of the heart. The researchers noted that radiation therapy has proven effective in reducing local recurrence and improving 10-year overall survival for breast cancer patients.
However, “reports from SEER database showed that it could increase the relative risk of cardiovascular death in 10 years, counterbalancing its improvement in overall survival.
“The relation between doses to cardiac structures and toxicity has never been well defined and most of the studies only analyze the whole heart dose,” the authors said in the article
“Analysis of IMRT and IGRT in Coronary Sparing in Patients With Left-sided Breast Cancer.”
Participants were treated with IMRT using a hybrid-DAO technique (h-DAO), with positioning errors performed daily using cone beam images, the authors stated. The researchers simulated a field in field (FIF) and a conformal technique (3D) at a prescribed dose of 50 Gy, 2 Gy per day. The maximum (Dmax) and median dose were then analyzed as they related to the left anterior descendent coronary, left ventricle and the heart.
The isocenter was modified based on observed values and the hDAO technique compared to the hypothetical uncorrected isocenter to determine if cone beam correction would decrease the heart dose. The median dose delivered in the h-DAO technique was 464 cGy compared to 949 cGy in the FIF and 1382 cGy with the 3D technique.
“The analysis of the h-DAO with IGRT showed a reduction of 47 percent, 59 percent and 65 percent in the median dose in LADC, LV and the heart,” the authors found.
The abstract for the article, printed in the Journal of Clinical Oncology, is available at http://abstract.asco.org/AbstView_102_84797.html .
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