***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: A prospect i ve study was initiated to assess the side-effects of postoperative adjuvant radiotherapy in patients with left-sided early breast cancer . Twelve patients with early breast cancer were examined before and a year after radiotherapy . Echocardiography , ECG and bicycle ergometry stress test with technetium-99 m sestamibi myocardial perfusion scintigraphic were carried out to assess changes in regional myocardial blood flow . Six of the 12 patients had new fixed scintigraphic defects after radiotherapy ( as compared with the preradiation examination ) . The localization of the defects corresponded well with the irradiated volume of the left ventricle . These defects were probably due to microvascular damage to the myocardium . Neither ECG changes nor left ventricular segmental wall motion abnormalities could be detected by echocardiography . To our knowledge this study is the first to show that radiation-induced microvascular damage to the myocardium may be detected by perfusion scintigraphy . This may limit the use of scintigraphy in diagnosing coronary artery disease in patients treated with thoracic radiotherapy .  Long-term follow-up is necessary to assess whether the presence of microvascular damage is a prognostic sign for the development of radiation-induced coronary artery disease PURPOSE To study incidence of radiation-related heart disease in a large population of breast cancer patients followed for up to 30 years . MATERIAL AND METHODS 72,134 women diagnosed with breast cancer in Denmark or Sweden during 1976 - 2006 and followed prospect ively . Radiation-related risk was studied by comparing women with left-sided and right-sided tumours . RESULTS 34,825 women ( 48 % ) received radiotherapy . Among unirradiated women tumour laterality had little relevance to heart disease . Among irradiated women mean dose to the whole heart was 6.3 Gy for left-sided tumours and 2.7 Gy for right-sided tumours . Mortality was similar in irradiated women with left-sided and right-sided tumours , but incidence ratios , left-sided versus right-sided , were raised : acute myocardial infa rct ion 1.22 ( 95 % CI 1.06 - 1.42 ) , angina 1.25 ( 1.05 - 1.49 ) , pericarditis 1.61 ( 1.06 - 2.43 ) , valvular heart disease 1.54 ( 1.11 - 2.13 ) . Incidence ratios for all heart disease were as high for women irradiated since 1990 ( 1.09 [ 1.00 - 1.19 ] ) as for women irradiated during 1976 - 1989 ( 1.08 [ 0.99 - 1.17 ] ) , and were higher for women diagnosed with ischaemic heart disease prior to breast cancer than for other women ( 1.58 [ 1.19 - 2.10 ] versus 1.08 [ 1.01 - 1.15 ] , p for difference=0.01 ) . CONCLUSIONS Breast cancer radiotherapy has , at least until recently , increased the risk of developing ischaemic heart disease , pericarditis and valvular disease .  Women with ischaemic heart disease before breast cancer diagnosis may have incurred higher risks than others Objective ( s ) : Radiation therapy for breast cancer can induce myocardial capillary injury and increase cardiovascular morbidity and mortality . A prospect i ve cohort was conducted to study the prevalence of myocardial perfusion abnormalities following radiation therapy of left-sided breast cancer patients as compared to those with right – sided cancer . Methods : To minimize potential confounding factors , only those patients with low 10-year risk of coronary artery disease ( based on Framingham risk scoring ) were included . All patients were initially treated by modified radical mastectomy  and then were managed by postoperative 3D Conformal Radiation Therapy ( CRT ) to the surgical bed with an additional 1-cm margin , delivered by 46 - 50 Gy ( in 2 Gy daily fractions ) over a 5-week course . The same dose-adjusted chemotherapy regimen ( including anthracyclines , cyclophosphamide and taxol ) was given to all patients . Six months after radiation therapy , all patients underwent cardiac SPECT for the evaluation of myocardial perfusion . Results : A total of 71 patients with a mean age of 45.3±7.2 years [ 35 patients with leftsided breast cancer ( exposed ) and 36 patients with right-sided cancer ( controls ) ] were enrolled  . Dose-volume histogram ( DVH ) [ showing the percentage of the heart exposed to > 50 % of radiation ] was significantly higher in patients with left-sided breast cancer . Visual interpretation detected perfusion abnormalities in 42.9 % of cases and 16.7 % of controls ( P=0.02 , Odds ratio=1.46 ) . In semiquantitative segmental analysis , only apical ( 28.6 % versus 8.3 % , P=0.03 ) and anterolateral ( 17.1 % versus 2.8 % , P=0.049 ) walls showed significantly reduced myocardial perfusion in the exposed group . Summed Stress Score ( SSS ) of>3 was observed in twelve cases ( 34.3 % ) , while in five of the controls (13.9%),(Odds ratio=1.3 ) . There was no significant difference between the groups regarding left ventricular ejection fraction . Conclusion : The risk of radiation induced myocardial perfusion abnormality in patients treated with CRT on the left hemi thorax is not low . It is reasonable to minimize the volume of the heart being in the field of radiation employing didactic radiation planning techniques . Also it is advisable to screen these patients with MPI-SPECT , even if they are clinical ly asymptomatic , as early diagnosis and treatment of silent ischemia may change the outcome PURPOSE To assess cardiac mortality , coronary artery disease , myocardial dysfunction , and valvular heart disease in women younger than 65 years of age , at least 10 years after adjuvant radiotherapy following mastectomy in early breast cancer . METHODS AND MATERIAL S Ninety women ( 45 - 64 years old ) with Stage II breast cancer without relapse , included in the South Sweden Breast Cancer Trial ( premenopausal arm ) , with or without adjuvant postoperative radiotherapy + /- cyclophosphamide  were examined with myocardial scintigraphy and echocardiography/Doppler , 10 - 17 years after radiotherapy .  Thirty-four patients had been irradiated for left-sided tumors , 33 for right-sided tumors , and 23 patients had not been treated with radiotherapy . The radiotherapy ( conventional roentgen , electron beams , and high-energy photon beams combined , in each patient ) included the chest wall and the regional lymph nodes , with a specified target dose of 38 - 48 Gy , administered in daily fractions of 1.9 - 2.4 Gy , 5 days/week . RESULTS No cardiac deaths were found among the original 275 patients r and omized to adjuvant therapy . In the 90 patients examined , abnormal findings were recorded for ECG ( 14 patients ) , exercise test ( 5 patients ) , myocardial scintigraphy ( 6 patients ) , thickening of valve cusps ( 14 patients ) , and mild valvular regurgitation ( 20 patients ) . All patients had normal systolic function . Diastolic dysfunction was observed in 6 patients ( abnormal relaxation in 4 patients and restrictive filling abnormality in 2 patients ) . Although no significant differences were found between the 3 study groups , there was a tendency to more abnormal findings after radiotherapy . CONCLUSION Women younger than 50 years of age at the time of adjuvant radiotherapy following mastectomy in early breast cancer , had no serious cardiac sequelae 13 years ( median ) later , despite partly old-fashioned radiation techniques PURPOSE  Radiation therapy ( RT ) for left-sided breast cancer has been associated with cardiac dysfunction . We herein assess the temporal nature and volume dependence of RT-induced left ventricular perfusion defects and whether these perfusion defects are related to changes in cardiac wall motion or alterations in ejection fraction . METHODS From 1998 to 2001 , 114 patients were enrolled onto an IRB-approved prospect i ve clinical study to assess changes in regional and global cardiac function after RT for left-sided breast cancer . Patients were imaged 30 to 60 minutes after injection of technetium 99 m sestamibi or tetrofosmin . Post-RT perfusion scans were compared with the pre-RT studies to assess for RT-induced perfusion defects as well as functional changes in wall motion and ejection fraction . Two-tailed Fisher 's exact test and the Cochran-Armitage test for linear trends were used for statistical analysis . RESULTS The incidence of new perfusion defects 6 , 12 , 18 , and 24 months after RT was 27 % , 29 % , 38 % , and 42 % , respectively . New defects occurred in approximately 10 % to 20 % and 50 % to 60 % of patients with less than 5 % , and greater than 5 % , of their left ventricle included within the RT fields , respectively ( p = 0.33 to 0.00008 ) . The rates of wall motion abnormalities in patients with and without perfusion defects were 12 % to 40 % versus 0 % to 9 % , respectively ; p values were 0.007 to 0.16 , depending on the post-RT interval . CONCLUSIONS Radiation therapy causes volume-dependent perfusion defects in approximately 40 % of patients within 2 years of RT . These perfusion defects are associated with corresponding wall-motion abnormalities . Additional study is necessary to better define the long-term functional consequences of RT-induced perfusion defects PURPOSE It is unknown whether irradiation of the internal mammary lymph nodes improves survival in patients with early-stage breast cancer . A possible survival benefit might be offset by radiation-induced heart disease . We assessed the effect of internal mammary node irradiation ( IMNI ) in patients with early-stage node-positive breast cancer . PATIENTS AND METHODS In this nationwide , prospect i ve population -based cohort study , we included patients who underwent operation for unilateral early-stage node-positive breast cancer . Patients with right-sided disease were allocated to IMNI , whereas patients with left-sided disease were allocated to no IMNI because of the risk of radiation-induced heart disease . The primary end point was overall survival . Secondary end points were breast cancer mortality and distant recurrence . Analyses were by intention to treat . RESULTS A total of 3,089 patients were included . Of these , 1,492 patients were allocated to IMNI , whereas 1,597 patients were allocated to no IMNI . With a median of 8.9 years of follow-up time , the 8-year overall survival rates were 75.9 % with IMNI versus 72.2 % without IMNI . The adjusted hazard ratio ( HR ) for death was 0.82 ( 95 % CI , 0.72 to 0.94 ; P = .005 ) . Breast cancer mortality was 20.9 % with IMNI versus 23.4 % without IMNI ( adjusted HR , 0.85 ; 95 % CI , 0.73 to 0.98 ; P = .03 ) . The risk of distant recurrence at 8 years was 27.4 % with IMNI versus 29.7 % without IMNI ( adjusted HR , 0.89 ; 95 % CI , 0.78 to 1.01 ; P = .07 ) . The effect of IMNI was more pronounced in patients at high risk of internal mammary node metastasis . Equal numbers in each group died of ischemic heart disease . CONCLUSION In this naturally allocated , population -based cohort study , IMNI increased overall survival in patients with early-stage node-positive breast cancer PURPOSE Cardiac muscle perfusion , as determined by single-photon emission computed tomography ( SPECT ) , decreases after breast and /or chest wall ( BCW ) irradiation . The active breathing coordinator ( ABC ) enables radiation delivery when the BCW is farther from the heart , thereby decreasing cardiac exposure . We hypothesized that ABC would prevent radiation-induced cardiac toxicity and conducted a r and omized controlled trial evaluating myocardial perfusion changes after radiation for left-sided breast cancer with or without ABC . METHODS AND MATERIAL S Stages I to III left breast cancer patients requiring adjuvant radiation therapy ( XRT ) were r and omized to ABC or No-ABC .  Myocardial perfusion was evaluated by SPECT scans ( before and 6 months after BCW radiation ) using 2 methods : ( 1 ) fully automated quantitative polar mapping ; and ( 2 ) semiquantitative visual assessment . The left ventricle was divided into 20 segments for the polar map and 17 segments for the visual method . Segments were grouped by anatomical rings ( apical , mid , basal ) or by coronary artery distribution . For the visual method , 2 nuclear medicine physicians , blinded to treatment groups , scored each segment 's perfusion . Scores were analyzed with nonparametric tests and linear regression . RESULTS Between 2006 and 2010 , 57 patients were enrolled and 43 were available for analysis . The cohorts were well matched . The apical and left anterior descending coronary artery segments had significant decreases in perfusion on SPECT scans in both 
    Output:
    
Conclusions Data suggest that incidental irradiation of the heart in cases of left breast/chest wall RT can result in early post-RT perfusion defects on cardiac SPECT .