Dose-modeling study to compare external beam techniques from protocol NSABP B-39/RTOG 0413 for patients with highly unfavorable cardiac anatomy.
ABSTRACT The aim of this study was to select patients with heart anatomy that is specifically unfavorable for tangential irradiation in whole-breast radiotherapy (WBRT), to be used as an experimental cohort to compare cardiac dosimetric and radiobiological parameters of three-dimensional conformal external beam accelerated partial breast irradiation (3D-CRT APBI) to WBRT with techniques as defined by the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-39/Radiation Therapy Oncology Group (RTOG) 0413 clinical trial.
A dosimetric modeling study that compared WBRT and 3D-CRT APBI was performed on CT planning data from 8 patients with left-sided breast cancer. Highly unfavorable cardiac anatomy was defined by the measured contact of the myocardium with the anterior chest wall in the axial and para-sagittal planes. Treatment plans of WBRT and 3D-CRT APBI were generated for each patient in accordance with NSABP B-39/RTOG 0413 protocol. Dose-volume relationships of the heart, including the V5min (minimum dose delivered to 5% of the cardiac volume), biological effective dose (BED) of the V5min, and normal tissue complication probability (NTCP) were analyzed and compared.
Despite expected anatomic variation, significantly large differences were found favoring 3D-CRT APBI in cumulative dose-volume histograms (p < 0.01), dose to the entire heart (mean difference 3.85 Gy, p < 0.01), NTCP (median difference, 1.00 Gy; p < 0.01), V5min (mean difference, 24.53 Gy; p < 0.01), and proportional reduction in radiobiological effect on the V5min (85%, p < 0.01).
Use of 3D-CRT APBI can demonstrate improved sparing of the heart in select patients with highly unfavorable cardiac anatomy for WBRT, and may result in reduced risk of cardiac morbidity and mortality.
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ABSTRACT: To evaluate postradiation regional heart perfusion changes with single photon emission tomography (SPECT) myocardial perfusion imaging in 69 patients treated with tangential photon beams radiation therapy (RT) for left-sided breast cancer. To correlate SPECT changes with percent irradiated left ventricle (LV) volume and risk factors for coronary artery disease (CAD). Rest SPECT of the LV was acquired pre-RT and at 6-month intervals post-RT. The extent of defects (%) with a severity > 1.5 standard deviations below the mean was quantitatively analyzed for the distributions of the left anterior descending (LAD) artery, left circumflex (LCX) artery, and right coronary artery (RCA) based on computer assisted polar map reconstruction (i.e., bull's-eye-view). Changes in perfusion were correlated with percent irradiated LV receiving > 25 Gy (range 0-32%). Data on patient- and treatment-related factors were collected prospectively (e.g., cardiac premorbidity, risk factors for CAD, chemotherapy, and hormonal treatment). In the LAD distribution, there were increased perfusion defects at 6 months (median 11%; interquartile range 2-23) compared with baseline (median 5%; interquartile range 1-14) (p < 0.001). There were no increases in perfusion defects in the LCX or RCA distributions. In multivariate analysis, the SPECT perfusion changes in the LAD distribution at 6 months were independently associated with percent irradiated LV (p < 0.001), hormonal therapy (p = 0.005), and pre-RT hypercholesterolemia (p = 0.006). The SPECT defects in the LAD distribution at 12 and 18 months were not statistically different from those at 6 months. The perfusion defects in the LAD distribution were limited essentially to the regions of irradiated myocardium. Tangential photon beam RT in patients with left-sided breast cancer was associated with short-term SPECT defects in the vascular distribution corresponding to the radiation portals. Factors related to the extent of perfusion defects included the percent irradiated LV, hormonal treatment, and pre-RT hypercholesterolemia.International Journal of Radiation OncologyBiologyPhysics 03/2003; 55(4):914-20. · 4.52 Impact Factor
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ABSTRACT: Women with breast cancer who are treated with adjuvant radiation have a decreased risk of local recurrence but an increased risk of mortality from ischemic heart disease. Patients with left-sided breast tumors receive a higher dose of radiation to the heart than patients with right-sided tumors. Because radiation techniques have improved over time, we investigated whether the risk of death from ischemic heart disease after adjuvant breast radiotherapy decreased over time. We used the 12-registry 1973-2000 dataset from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program. Women (n = 27,283) treated with adjuvant radiation for breast cancer diagnosed in 1973-1989 were included in the study. Ischemic heart disease mortality was calculated at 15 years and compared for women diagnosed during 1973-1979, 1980-1984, and 1985-1989. Cox proportional hazards models were used to calculate the hazard of death from ischemic heart disease for women diagnosed 1973-1988 and censored at 12 years. All statistical tests were two-sided. There were no differences in age, race/ethnicity, disease stage, or follow-up time between the 13 998 women with left-sided and 13 285 with right-sided cancer. For women diagnosed in 1973-1979, there was a statistically significant difference in 15-year mortality from ischemic heart disease between patients with left-sided (13.1%, 95% confidence interval [CI] = 11.6 to 14.6) and those with right-sided (10.2%, 95% CI = 8.9 to 11.5) breast cancer (P = .02); no such difference was found for women diagnosed in 1980-1984 (9.4%, [95% CI = 8.1 to 10.6] versus 8.7% [95% CI = 7.4 to 10.0], respectively, P = .64) or 1985-1989 (5.8% [95% CI = 4.8 to 6.8] versus 5.2% [95% CI = 4.4 to 5.9], respectively, P = .98). In the Cox model, the hazard ratio [HR] for ischemic heart disease mortality for women with left-sided versus women with right-sided disease was 1.50 (95% CI = 1.19 to 1.87) in 1979. With each succeeding year after 1979, the hazard of death from ischemic heart disease for women with left-sided versus those with right-sided disease declined by 6% (HR = 0.94, 95% CI = 0.91 to 0.98). Risk of death from ischemic heart disease associated with radiation for breast cancer has substantially decreased over time.CancerSpectrum Knowledge Environment 04/2005; 97(6):419-24. · 14.07 Impact Factor
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ABSTRACT: To evaluate the risk of coronary heart disease (CHD) and cerebrovascular disease after radiotherapy (RT) for peptic ulcer disease. Peptic ulcer disease patients treated with RT (n = 1859) or by other means (n = 1860) at the University of Chicago Medical Center between 1936 and 1965, were followed through 1997. The observed numbers of cause-specific deaths were compared with the expected numbers from the general population rates. During RT, 5% of the heart was in the treatment field and the remainder of the heart mostly received scattered radiation. A volume-weighted cardiac dose was computed to describe the average tissue dose to the entire organ. We used Cox proportional hazards regression analysis to analyze the CHD and cerebrovascular disease risk associated with RT, adjusting for confounding factors. Greater than expected CHD mortality was observed among the irradiated patients. The irradiated patients received volume-weighted cardiac doses ranging from 1.6 to 3.9 Gy and the portion of the heart directly in the field received doses of 7.6-18.4 Gy. The CHD risk increased with the cardiac dose (p trend = 0.01). The cerebrovascular disease risk was not associated with the surrogate carotid dose. The excess CHD risk in patients undergoing RT for peptic ulcer disease decades previously indicates the need for long-term follow-up for cardiovascular disease after chest RT.International Journal of Radiation OncologyBiologyPhysics 04/2005; 61(3):842-50. · 4.52 Impact Factor