Recent time trends and predictors of heart dose from breast radiotherapy in a large quality consortium of radiation oncology practices

Publication date: Available online 22 July 2017
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Lori J. Pierce, Mary Feng, Kent A. Griffith, Reshma Jagsi, Thomas Boike, Daniel Dryden, Gregory S. Gustafson, Lisa Benedetti, Martha M. Matuszak, Teamour S. Nurushev, Joe Haywood, Jeffrey D. Radawski, Corey Speers, Eleanor M. Walker, James A. Hayman, Jean M. Moran
IntroductionLimited data exist regarding the range of heart doses received in routine practice following radiotherapy (RT) for breast cancer (BC) in the United States today and the potential impact of continual assessment of cardiac dose on practice patterns.Methods and MaterialsFrom 2012-2015, 4688 patients with BC treated with whole breast RT at 20 sites participating in a state-wide consortium were enrolled into a registry. The importance of limiting cardiac dose has been emphasized in the consortium since 2012 and mean heart dose (MHD) has been reported to each institution since 2014. Effects on MHD were estimated for both conventional fractionation (CF) and accelerated fractionation (AF) using regression models with technique (intensity modulated RT, IMRT vs. three-dimensional conformal RT, 3DCRT), deep-inspiration breath hold (DIBH) use, position (supine vs. prone), nodal RT (if delivered) and boost (yes/no) as covariates.ResultsFor left-sided BC treated with CF, median MHD in 2012 was 2.19 Gy compared to 1.65 Gy in 2015 (p<0.001). Factors which significantly increased MHD for CF were increasing separation relative to 22 cm (1.5%/cm) ; supra-/infraclavicular node RT (17.1%); internal mammary node RT (40.7%); use of boost (20.9%); treatment per year prior to 2015 (7.7%); and IMRT (20.8%). For left-sided BC treated with AF, the median MHD in 2012 was 1.70 Gy versus 1.22 Gy in 2015 (p<0.001). Factors that significantly increased MHD following AF were separation (1.7% /cm); use of boost (20.0%); year prior to 2015 (8.5%); and IMRT (19.2%). Factors for both CF and AF that significantly reduced MHD were use of DIBH and prone positioning.ConclusionsMHD for left-sided cancers has decreased over a recent 4-year period coincident with increased focus on cardiac sparing in the radiation oncology community in general and within a state-wide consortium specifically. These data suggest a positive impact of systematically monitoring heart dose delivered.

Teaser

With recent focus on minimizing radiation dose to the heart following adjuvant therapy for breast cancer, it is important to understand the current state of cardiac sparing and predictors of heart dose. In a large U.S. state-wide registry, we evaluated recent time trends in mean heart dose, adjusting for planned target dose and treatment technique. Our findings indicate mean heart dose decreased significantly for left-sided breast cancers over a 4-year period using ongoing monitoring of cardiac dose by institution.


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