No serious late cardiac effects after adjuvant radiotherapy following mastectomy in premenopausal women with early breast cancer

Cardiac structure, function, and coronary anatomy 10 years after isolated contemporary adjuvant radiotherapy in breast cancer patients with low cardiovascular baseline risk

AIMS

The effects of isolated contemporary low-dose breast cancer (BC) radiotherapy (RT) on the heart remain poorly understood. This study aims to assess the long-term impacts of BC-RT on cardiac structure and function.

METHODS AND RESULTS

Seventy-six women (62 ± 7 years) without history of prior heart disease, who had undergone RT for either first left (n = 36) or right (n = 40) BC, without additional medical oncology therapy apart from hormonal treatment 11 ± 1 years earlier, underwent transthoracic echocardiography, cardiac magnetic resonance imaging (CMR), computed tomography coronary angiography (CTCA), NT-proBNP, and a 6-min walk test (6MWT). They were compared with 54 age-matched healthy female controls. By CTCA, 68% of BC patients exhibited no or very mild coronary disease, while only 11% had moderate stenosis (50-69%) and 3% had significant stenosis (>70%). Despite slightly reduced regional echocardiographic midventricular strains, BC patients exhibited similar global left and right ventricular volumes, ejection fractions, and global strains by echocardiography and CMR as controls. Mitral E/e' ratios were slightly higher, and mitral deceleration times were slightly lower, but NT-proBNP was similar to controls. Also, 6MWT was normal. None had late gadolinium enhancement, and extracellular volume fraction was similar in BC (28 ± 3 vs. 29 ± 3, P = 0.15) and controls. No differences were observed relative to dose or side of RT.

CONCLUSION

Aside from minor alterations of regional strains and diastolic parameters, women who received isolated RT for BC had low prevalence of coronary disease, normal global systolic function, NT-proBNP, and exercise capacity and showed no structural changes by CMR, refuting significant long-term cardiotoxicity in such low-risk patients.

Post-mastectomy radiotherapy for women with early breast cancer and one to three positive lymph nodes

BACKGROUND

Continual improvement in adjuvant therapies has resulted in a better prognosis for women diagnosed with breast cancer. A surrogate marker used to detect the spread of disease after treatment of breast cancer is local and regional recurrence. The risk of local and regional recurrence after mastectomy increases with the number of axillary lymph nodes affected by cancer. There is a consensus to use radiotherapy as an adjuvant treatment after mastectomy (postmastectomy radiotherapy (PMRT)) in women diagnosed with breast cancer and found to have disease in four or more positive axillary lymph nodes. Despite data showing almost double the risk of local and regional recurrence in women treated with mastectomy and found to have one to three positive lymph nodes, there is a lack of international consensus on the use of PMRT in this group.

OBJECTIVES

To assess the effects of PMRT in women diagnosed with early breast cancer and found to have one to three positive axillary lymph nodes.

SEARCH METHODS

We searched the Cochrane Breast Cancer Group's Specialised Register, CENTRAL, MEDLINE, Embase, the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) and ClinicalTrials.gov up to 24 September 2021.

SELECTION CRITERIA

We included randomised controlled trials (RCTs). The inclusion criteria included women diagnosed with breast cancer treated with simple or modified radical mastectomy and axillary surgery (sentinel lymph node biopsy (SLNB) alone or those undergoing axillary lymph node clearance with or without prior SLNB). We included only women receiving PMRT using X-rays (electron and photon radiation), and we defined the radiotherapy dose to reflect what is currently being recommended (i.e. 40 Gray (Gy) to 50 Gy in 15 to 25/28 fractions in 3 to 5 weeks. The included studies did not administer any boost to the tumour bed. In this review, we excluded studies using neoadjuvant chemotherapy as a supportive treatment before surgery.

DATA COLLECTION AND ANALYSIS

We used Covidence to screen records. We collected data on tumour characteristics, adjuvant treatments and the outcomes of local and regional recurrence, overall survival, disease-free survival, time to progression, short- and long-term adverse events and quality of life. We reported on time-to-event outcome measures using the hazard ratio (HR) and subdistribution HR. We used Cochrane's risk of bias tool (RoB 1), and we presented overall certainty of the evidence using the GRADE approach.

MAIN RESULTS

The RCTs included in this review were subgroup analyses of original RCTs conducted in the 1980s to assess the effectiveness of PMRT. Hence, the type and duration of adjuvant systemic treatments used in the studies included in this review were suboptimal compared to the current standard of care. The review involved three RCTs with a total of 829 women diagnosed with breast cancer and low-volume axillary disease. Amongst the included studies, only a single study pertained to the modern-day radiotherapy practice. The results from this one study showed a reduction of local and regional recurrence (HR 0.20, 95% confidence interval (CI) 0.13 to 0.33, 1 study, 522 women; low-certainty evidence) and improvement in overall survival with PMRT (HR 0.76, 95% CI 0.60 to 0.97, 1 study, 522 women; moderate-certainty evidence). One of the other studies using radiotherapy techniques that do not reflect modern-day practice reported on disease-free survival in women with low-volume axillary disease (subdistribution HR 0.63, 95% CI 0.41 to 0.96, 1 study, 173 women). None of the included studies reported on PMRT side effects or quality-of-life outcome measures.

AUTHORS' CONCLUSIONS

Based on one study, the use of PMRT in women diagnosed with breast cancer and low-volume axillary disease indicated a reduction in locoregional recurrence and an improvement in survival. There is a need for more research to be conducted using modern-day radiotherapy equipment and methods to support and supplement the review findings.

15O-H2O PET/CT as a tool for the quantitative assessment of early post-radiotherapy changes of heart perfusion in breast carcinoma patients

OBJECTIVE

Studies examining radiation-induced heart toxicity in breast cancer patients are inconclusive. The aim of this study was to prospectively and quantitatively asses myocardial blood flow (MBF) with, for the first time, ¹⁵O-H₂O PET/CT as a marker of heart damage in irradiated breast cancer patients.

METHODS

15 breast cancer patients receiving intact breast or chest wall irradiation were included in the analysis (six with right-sided and nine with left-sided breast cancer). They underwent ¹⁵O-H₂O PET/CT before radiotherapy (RT) and 2 and 8 months after RT. MBF was quantitatively assessed at rest and under stress conditions in 17 heart segments distinguished according to the American Ultrasound Association classification. Regional MBF values were derived in each of the coronary artery territories.

RESULTS

MBF decreased in 53% and increased in 33% of cases 2 months after RT in both left-sided and right-sided breast cancer patients. Stress testing was more sensitive than at-rest testing, demonstrating decreased perfusion in the segments supplied by the left anterior descending coronary artery (LAD) [5.41 ± 1.74 vs 4.52 ± 1.82 ml (g*min)^-1; p = 0.018], which persisted at 6 months [5.41 ± 1.74 vs 4.40 ± 1.38 ml (g*min)^-1; p = 0.032] and a decrease in global heart perfusion [5.14 ± 1.49 vs 4.46 ± 1.73 ml (g*min)^-1; p = 0.036]. A minimal radiation dose applied to the LAD correlated with MBF changes observed 2 months after RT (r = -0.57; p = 0.032). Radiological findings were not correlated with clinical symptoms of heart toxicity.

CONCLUSION

¹⁵O-H₂O PET/CT is safe and effective for the early detection and quantitative analysis of subclinical post-RT changes in heart perfusion in breast cancer patients. The LV segments supplied by the LAD are the main site of MBF changes. A minimum radiation dose deposited in the LAD may be a predictor of radiation-induced heart toxicity. Advances in knowledge: This is the first time that ¹⁵O-H₂O PET/CT has been used to assess MBF after RT and the first granular description of the distribution of blood flow changes after breast cancer RT.

Strain Imaging Detects Dose-Dependent Segmental Cardiac Dysfunction in the Acute Phase After Breast Irradiation

PURPOSE

We examined the utility of echocardiographic 2-dimensional speckle tracking strain imaging (SI) for the evaluation of segmental myocardial dysfunction before and after radiation therapy (RT) and the relationship to dose exposure.

METHODS AND MATERIALS

We prospectively recruited 40 women with left-sided breast cancer, undergoing only adjuvant RT to the left chest. Comparisons of traditional echocardiographic parameters and SI parameters at baseline and 6 weeks after RT were analyzed. Regional strain and strain rate (SR) parameters were obtained from all 18 left ventricular segments. The correlation of change in strain parameters with segmental radiation dose was examined.

RESULTS

We observed a significant reduction in global and segmental systolic strain parameters at 6 weeks after RT compared with baseline, with the largest decrement in the apical segments; this corresponded with the segments receiving the highest radiation dose exposure (apical peak systolic strain of -21.21% ± 3.49% before RT vs -18.69% ± 3.34% after RT, percentage change of 11.88%, P=.002; apical peak systolic SR of -1.17 ± 0.24 s^-1 before RT vs -1.04 ± 0.19 s^-1 after RT, percentage change of 11.11%, P=.008). There was a modest correlation between the apical segment systolic strain reduction and radiation dose exposure (apical segment Δ change and apical radiation dose, r=0.345, P=.031; apical segment percentage change and apical radiation dose, r=0.346, P=.031). A significant reduction in early diastolic SR was observed in the apical segments after treatment compared with baseline (apical early diastolic SR, 1.54 ± 0.45 s^-1 before RT vs 1.35 ± 0.33 after RT s^-1; percentage change, 12.34%; P=.034).

CONCLUSIONS

Two-dimensional SI detected dose-related regional myocardial dysfunction in the acute phase after RT in chemotherapy-naive left-sided breast cancer patients. Although the long-term effects remain unknown, this imaging modality may have a potential role in the evaluation of irradiation-related cardiotoxicity.

Long-term cardiovascular mortality after radiotherapy for breast cancer: A systematic review and meta-analysis

BACKGROUND

Radiotherapy (RT) is frequently associated with late cardiovascular (CV) complications. The mean cardiac dose from irradiation of a left-sided breast cancer is much higher than that for a right-sided breast cancer. However, data is limited on the long-term risks of RT on CV mortality.

HYPOTHESIS

RT for breast cancer is associated with long term CV mortality and left sided RT carries a greater mortality than right sided RT.

METHODS

We searched PubMed, Cochrane Central, Embase, EBSCO, Web of Science, and CINAHL databases from inception through December 2015. Studies reporting CV mortality with RT for left- vs right-sided breast cancers were included. The principal outcome of interest was CV mortality. We calculated summary risk ratio (RR) and 95% confidence intervals (CI) with the random-effects model.

RESULTS

The analysis included 289 109 patients from 13 observational studies. Women who had received RT for left-sided breast cancer had a higher risk of CV death than those who received RT for a right-sided breast cancer (RR: 1.12, 95% CI: 1.07-1.18, P < 0.001; number needed to harm: 353). Difference in CV mortality between left- vs right-sided breast RT was more apparent after 15 years of follow-up (RR: 1.23, 95% CI: 1.08-1.41, P < 0.001; number needed to harm: 95).

CONCLUSIONS

CV mortality from left-sided RT was significantly higher compared with right-sided RT for breast cancer and was more apparent after ≥15 years of follow-up.

The utility of cardiac stress testing for detection of cardiovascular disease in breast cancer survivors: a systematic review

Background

Heart function tests performed with myocardial stress, or “cardiac stress tests”, may be beneficial for detection of cardiovascular disease. Women who have been diagnosed with breast cancer are more likely to develop cardiovascular diseases than the general population, in part due to the direct toxic effects of cancer treatment on the cardiovascular system. The aim of this review was to determine the utility of cardiac stress tests for the detection of cardiovascular disease after cardiotoxic breast cancer treatment.

Design

Systematic review.

Methods

Medline and Embase were searched for studies utilizing heart function tests in breast cancer survivors. Studies utilizing a cardiac stress test and a heart function test performed at rest were included to determine whether stress provided added benefit to identifying cardiac abnormalities that were undetected at rest within each study.

Results

Fourteen studies were identified. Overall, there was a benefit to utilizing stress tests over tests at rest in identifying evidence of cardiovascular disease in five studies, a possible benefit in five studies, and no benefit in four studies. The most common type of stress test was myocardial perfusion imaging, where reversible perfusion defects were detected under stress in individuals who had no defects at rest, in five of seven studies of long-term follow-up. Two studies demonstrated the benefit of stress echocardiography over resting echocardiography for detecting left ventricular dysfunction in anthracycline-treated breast cancer survivors. There was no benefit of stress cardiac magnetic resonance imaging in one study. Two studies showed a potential benefit of stress electrocardiography, whereas three others did not.

Conclusion

The use of cardiac stress with myocardial perfusion imaging and echocardiography may provide added benefit to tests performed at rest for detection of cardiovascular disease in breast cancer survivors, and merits further research.

Evaluation of radiation-induced myocardial damage using iodine-123 β-methyl-iodophenyl pentadecanoic acid scintigraphy

We evaluated radiation-induced myocardial damage using iodine-123 β-methyl-iodophenyl pentadecanoic acid (I-123 BMIPP) scintigraphy. Between May 2010 and April 2011 we performed I-123 BMIPP scintigraphy for patients who had maintained complete response to curative radiotherapy (RT) for esophageal cancer for more than six months. We compared the area of the myocardium in the RT fields with that of reduced I-123 BMIPP uptake using a 15-segment model that is based on axial computed tomography (CT) images. We classified the segments into three categories: segments receiving 40 Gy (Segment 40 Gy), segments receiving 60 Gy (Segment 60 Gy) and segments out of the radiation fields (Segment 0 Gy). A segment with reduced uptake in the RT fields was defined as positive. A total of 510 segments in 34 patients were used for analysis. The median interval from completion of RT to I-123 BMIPP scintigraphy was 22 months (range, 6-103 months). The numbers of Segment 0 Gy, Segment 40 Gy and Segment 60 Gy were 324, 133 and 53, respectively. Reduced uptake was detected in 42.9% (57/133) of Segment 40 Gy, 67.9% (36/53) of Segment 60 Gy and 13.3% (43/324) of Segment 0 Gy. The odds ratios of 40 Gy and 60 Gy compared with regions out of the RT fields were 5.2 (95% confidence interval [CI]: 3.7-7.4) and 15.4 (95% CI: 6.9-34.6), respectively. Reduced myocardial I-123 BMIPP uptake in RT fields, suggesting RT-induced myocardial damage, was frequently observed. I-123 BMIPP myocardial scintigraphy may be useful for identifying RT-induced myocardial damage.

Delineation of the cardiac substructures based on PET-CT and contrast-enhanced CT in patients with left breast cancer treated with postoperative radiotherapy

The aim of this study is to evaluate the volume differences between contrast-enhanced CT-based left ventricle (LV) and PET-CT-based LV and assess the impact of dose on the substructure volume differences in patients with left breast cancer treated with adjuvant radiotherapy. From October 2008 to February 2009, 14 patients with post-operatively confirmed left breast cancer were enrolled in the current study. The patients were scanned using contrast-enhanced CT for simulation, and (18)F-FDG PET-CT was employed to display the structure of the left ventricle of each before radiotherapy (RT). The LV was delineated based on both contrast-enhanced CT and PET-CT. And other substructures, such as the left anterior descending coronary artery (LAD), were contoured in each patient, with the six-field simple intensity modulated radiotherapy (sIMRT) technique created for all. The mean volumes of the left ventricle based on contrast-enhanced CT (LV-CT) and PET-CT (LV-PET) were found to be 107.296 cm(3) and 112.931 cm(3), respectively (p = 0.06). The volume of LV receiving ≥ 50% prescription dose was significantly correlated with the volume of the heart receiving the same dosage (γ = 0.869). There was less correlation between the volume of LAD and that of the heart under the same condition (γ = 0.22). As a conclusion, the left ventricle can be delineated effectively based on the image of PET-CT, the contrast-enhanced CT based LV can serve as an appropriate alternative. Moreover, the volume of LV receiving high dose in RT closely correlated with the volume of the heart using sIMRT technique, which may pave the way for further exploring radiation-induced cardiac injuries in patients with left breast cancer.

Imaging radiation-induced normal tissue injury

Technological developments in radiation therapy and other cancer therapies have led to a progressive increase in five-year survival rates over the last few decades. Although acute effects have been largely minimized by both technical advances and medical interventions, late effects remain a concern. Indeed, the need to identify those individuals who will develop radiation-induced late effects, and to develop interventions to prevent or ameliorate these late effects is a critical area of radiobiology research. In the last two decades, preclinical studies have clearly established that late radiation injury can be prevented/ameliorated by pharmacological therapies aimed at modulating the cascade of events leading to the clinical expression of radiation-induced late effects. These insights have been accompanied by significant technological advances in imaging that are moving radiation oncology and normal tissue radiobiology from disciplines driven by anatomy and macrostructure to ones in which important quantitative functional, microstructural, and metabolic data can be noninvasively and serially determined. In the current article, we review use of positron emission tomography (PET), single photon emission tomography (SPECT), magnetic resonance (MR) imaging and MR spectroscopy to generate pathophysiological and functional data in the central nervous system, lung, and heart that offer the promise of, (1) identifying individuals who are at risk of developing radiation-induced late effects, and (2) monitoring the efficacy of interventions to prevent/ameliorate them.

Evaluation of cardiotoxicity five years after 2D planned, non-simulated, radiation therapy for left breast cancer

Introduction:

Radiation treatment has been associated with radiation induced cardiotoxicity, especially with older, long-outdated, techniques. Such complications include pericarditis, myocardial fibrosis, valvular injury, ischemic heart disease, and myocardial infarction.

Aim:

To assess the effect of outdated breast radiation therapy (RT) – using a diagnostic CT scanner in the absence of a CT simulator – on cardiac function in women with stage II left breast cancer.

Patients and Methods:

Sixty-two women under 65 with stage II left breast cancer who received post-operative RT using a diagnostic computed tomography scanner were studied between 1997 and 2001. Participants underwent a clinical interview, ECG, and echocardiography before and 6 months and 5 years after RT.

Results:

There was no serious cardiotoxicity at 6 months and 5 years after radiotherapy. A 23% increase in hypertensive patients, and a slight decrease (2.3%) in ejection fraction was observed after 5 years, with 3 patients (5%) developing abnormalities. Two patients presented abnormal electrocardiographic findings within 6 months of RT.

Conclusion:

Our study showed that RT for left breast cancer was not associated with significant alteration in heart morbidity or mortality within 5 years of treatment, despite the lack of a simulator.

Integrating bevacizumab into the treatment of patients with early-stage breast cancer: focus on cardiac safety

Significant advances have been made in the treatment of patients with breast cancer in recent years. As increasing numbers of patients become long-term survivors, there must be a greater focus on treatment-induced chronic toxicities, such as left ventricular dysfunction, congestive heart failure (CHF), and/or secondary treatment malignancies. More recently, the HER2-targeted monoclonal antibody (MoAb) trastuzumab has been found to increase the risk for CHF, particularly when used in combination with an anthracycline or in anthracycline-pretreated patients. In early-stage breast cancer, CHF has been reported in up to 4% of trastuzumab-treated, anthracycline-pretreated patients. Given this background, the clinical development of bevacizumab, a MoAb to vascular endothelial growth factor, is proceeding--with careful consideration given to cardiac safety--in this setting. Cardiac toxicity has been reported in association with bevacizumab-based therapy in patients with advanced or metastatic breast cancer, many of whom were previously exposed to anthracyclines. Although there is currently little evidence to suggest that bevacizumab increases the risk or worsens the severity of cardiac events in these patients, it is anticipated that ongoing, well-designed prospective trials will fully evaluate the cardiac safety of bevacizumab in patients with early-stage breast cancer. This review analyzes the cardiac safety profile of bevacizumab in breast cancer, with a focus on early-stage disease, and the ongoing clinical development of this important new drug.

Efficient reduction of loco-regional recurrences but no effect on mortality twenty years after postmastectomy radiation in premenopausal women with stage II breast cancer - a randomized trial from the South Sweden Breast Cancer Group

PURPOSE

To study long term loco-regional and distant recurrence rate and survival after post-mastectomy radiotherapy in combination with oral cyclophosphamide in premenopausal women with stage II breast cancer.

STUDY DESIGN

A three-armed randomized multicenter phase III trial comparing 1) Radiotherapy (RT) 2) RT+ oral cyclophosphamide for one year (RT+C) and 3) Oral cyclophosphamide only (C). Radiotherapy was administered, in 20 fractions, to 48Gy to the axilla and parasternal lymph nodes, 45Gy to infra- and supraclavicular fossae and 38Gy to the chest wall. Cyclophosphamide was prescribed as 12 courses of 130mg/m(2) od for 14 days every 4 weeks.

PATIENTS AND METHODS

367 patients from 15 surgical departments in Southern Sweden, representing 80% of all eligible patients, were included in the trial between 1978-1983. Median age was 47 years, median tumour size was 25mm, and 33% of the patients were lymph node negative. Median follow-up time was 24 years.

RESULTS

RT reduced the risk at twenty years for loco-regional recurrence in C-treated patients at twenty years with 75% (13.9% vs. 3.5%). The risk reduction was highly significant in both N0 and N+ patients. No reduction in systemic disease or mortality was observed.

CONCLUSION

Post-mastectomy radiotherapy reduced loco-regional recurrences in this premenopausal population, but no effect was seen on mortality with 20 years follow-up.

Prospective assessment of radiotherapy-associated cardiac toxicity in breast cancer patients: analysis of data 3 to 6 years after treatment

BACKGROUND

Radiation therapy (RT) to the left breast/chest wall has been linked with cardiac dysfunction. Previously, the authors identified cardiac perfusion defects in approximately 50% to 60% of patients 0.5 to 2 years post-RT. In the current study, they assessed the persistence of these defects 3 to 6 years post-RT.

METHODS

From 1998 to 2006, 160 patients with left-sided breast cancer were enrolled onto an Institutional Review Board-approved, prospective study. All patients received tangential photons to the left breast/chest wall. Patients had pre-RT and serial post-RT single-photon emission computed tomography (SPECT) scans to assess changes in regional cardiac perfusion, wall motion, and ejection fraction (EF). Forty-four patients had SPECT scans 3 to 6 years post-RT and were evaluable for the current analysis.

RESULTS

The overall incidence of perfusion defects at 3 years, 4 years, 5 years, and 6 years was 52% (11 of 21 patients), 71% (17 of 24 patients), 67% (12 of 18 patients), and 57% (4 of 7 patients), respectively. The rate of abnormal SPECT scans 3 to 6 years post-RT in patients who had scans at 0.5 to 2 years that were either all abnormal, intermittently abnormal, or all normal was 80%, 67%, and 63%, respectively. The incidence of wall motion abnormalities in patients with or without perfusion defects 3 to 6 years post-RT was low and did not differ statistically (17% vs 7.1%, respectively; P = .65), as was the incidence of reductions in EF of >/=5% (27% vs 36%, respectively; P = .72).

CONCLUSIONS

The results from this study indicated that RT-induced perfusion defects may persist or initially may appear 3 to 6 years post-RT in a high percentage of patients. However, these defects were not associated with changes in regional wall motion or EF. Additional study will be needed to determine the clinical relevance of these defects. In the meantime, the authors believe that every effort should be made to minimize incidental irradiation of the heart while maintaining adequate coverage of target volumes.

Impact of Fraction Size on Cardiac Mortality in Women Treated With Tangential Radiotherapy for Localized Breast Cancer

PURPOSE

To determine whether fraction size affects the risk of cardiac mortality in women treated with adjuvant radiotherapy (RT) for left-sided breast cancer.

METHODS AND MATERIALS

A population-based retrospective study of women with a diagnosis of localized breast cancer treated with adjuvant RT in British Columbia from 1984 to 2000. Cases were identified from the British Columbia Cancer Agency database. Overall and cardiac-specific survival were compared for women treated with RT for left- vs. right-sided breast cancer. We analyzed the impact of age (<or=60 vs. >60 years) at diagnosis and RT fraction size (<or=2 vs. >2 Gy) on risk of fatal cardiac events.

RESULTS

We identified 3,781 women with left-sided and 3,666 women with right-sided breast cancer who received adjuvant RT. Median follow-up was 7.9 years. There were 52 vs. 47 breast cancer deaths in women treated for left- and right-sided breast cancer, respectively. There was no significant difference in cardiac mortality for women <or=60 or >60 years of age who received adjuvant RT for left-sided vs. right-sided cancer. There was no difference in cardiac mortality for women who received adjuvant RT with fraction sizes <or=2 vs. >2 Gy for left- or right-sided cancer.

CONCLUSIONS

There was no evidence for increased risk of cardiac mortality in women treated with adjuvant RT after a median follow-up of 7.9 years in our cohort. Hypofractionated adjuvant RT regimens did not significantly increase the risk of cardiac mortality.

Cardiovascular effects of breast cancer radiotherapy

Cardiac toxicity has been implicated as the primary reason for excess non-breast cancer mortality in early breast cancer radiotherapy studies. Refinements in radiotherapy techniques have allowed for a considerable reduction of this risk in the majority of breast cancer patients. Recent large population-based studies confirmed an increase of cardiovascular death risk in patients irradiated for cancer of the left breast and in individuals exposed to relatively low (hitherto believed to be of no cardiovascular disease risk) doses of radiation, such as atomic bomb survivors or patients treated for various benign conditions. The issue of potential radiation-related cardiac damage may also be assuming a new significance due to the widespread use of other cardiotoxic agents, such as anthracyclines, paclitaxel and trastuzumab. The aim of this review is to summarize and critically analyze the available evidence on the impact of ionizing radiation on the cardiovascular system, with special attention to recent data demonstrating previously unrecognized adverse effects. This review discusses the pathology of radiation-related cardiovascular disease, its clinical presentation, risk factors and methods of assessment, as well as technical developments minimizing cardiac exposure. Epidemiological data are presented on the incidence of radiation-induced heart disease and cardiovascular mortality in various populations of patients irradiated for breast cancer and in individuals exposed to low radiation doses. Additionally, non-cardiac radiation-related vascular morbidity and mortality in breast cancer patients are addressed.

Radiation therapy, cardiac risk factors, and cardiac toxicity in early-stage breast cancer patients

PURPOSE

The benefits of adjuvant radiation therapy (RT) for breast cancer may be counterbalanced by the risk of cardiac toxicity. We studied the cardiac effects of RT and the impact of pre-existing cardiac risk factors (CRFs) in a population-based sample of older patients with breast cancer.

METHODS AND MATERIALS

In the Surveillance, Epidemiology and End-Results (SEER)-Medicare database of women > or = 65 years diagnosed with Stages I to III breast cancer from January 1, 1992 to December 31, 2000, we used multivariable logistic regression to model the associations of demographic and clinical variables with postmastectomy and postlumpectomy RT. Using Cox proportional hazards regression, we then modeled the association between treatment and myocardial infarction (MI) and ischemia in the 10 or more years after diagnosis, taking the predictors of treatment into account.

RESULTS

Among 48,353 women with breast cancer; 19,897 (42%) were treated with lumpectomy and 26,534 (55%) with mastectomy; the remainder had unknown surgery type (3%). Receipt of RT was associated with later year of diagnosis, younger age, fewer comorbidities, nonrural residence, and chemotherapy. Postlumpectomy RT was also associated with white ethnicity and no prior history of heart disease (HD). The RT did not increase the risk of MI. Presence of MI was associated with age, African American ethnicity, advanced stage, nonrural residence, more than one comorbid condition, a hormone receptor-negative tumor, CRFs and HD. Among patients who received RT, tumor laterality was not associated with MI outcome. The effect of RT on the heart was not influenced by HD or CRFs.

CONCLUSION

It appears unlikely that RT would increase the risk of MI in elderly women with breast cancer, regardless of type of surgery, tumor laterality, or history of CRFs or HD, for at least 10 years.

A population-based case-cohort study of the risk of myocardial infarction following radiation therapy for breast cancer

OBJECTIVE

To describe the risk of acute myocardial infarction (AMI) after radiation therapy (RT) for breast cancer (BrCa) in an exposed population.

METHODS

We identified and validated cases of AMI (vAMI), by electrocardiographic or enzyme criteria, among all 6680 women who received post-operative RT following lumpectomy or mastectomy, within 12 months following diagnosis of BrCa between 1982 and 1988 in Ontario, Canada. We identified women without vAMI whose death certification was ascribed to AMI (dAMI). We abstracted risk factors and treatment exposures for a random sample of women from the 6680, and for all with vAMI or dAMI. The hazards of vAMI and of dAMI were estimated using multivariate Cox proportional hazards models, corrected for study design.

RESULTS

We validated 121 cases of vAMI and identified 92 cases of dAMI. The risk of vAMI associated with RT to the left breast HR=1.96 (1.09,3.54) among women at age >/= 60 at time of RT, adjusted for history of smoking and prior MI. The adjusted HR dAMI=1.90 (1.08,3.35) for exposure to anterior internal mammary node (IMC) RT. Among women who received anterior left breast boost RT, increasing area of the boost is associated with adjusted HR vAMI=1.02 (1.00,1.03)/cm(2), and adjusted HR dAMI=1.02 (1.01,1.03)/cm(2).

CONCLUSION

The risks of vAMI and dAMI following RT for BrCa are related to anatomic sites of RT (left breast, area of anterior left breast boost field, and anterior IMC field).

Cardiac Risks of Breast-cancer Radiotherapy: A Contemporary View

For some time, there has been compelling evidence both from randomised-controlled trials and from observational studies, that some of the breast-cancer radiotherapy regimens used in the past have led to increased risk of mortality from heart disease. There is also some evidence that the more recent regimens used in the USA are associated with lower risks than previous ones, but it is not clear whether current regimens are free from cardiac risk, especially in the light of recent evidence from the survivors of the bombings of Hiroshima and Nagasaki, in whom a clear relationship was observed between the risk of mortality from heart disease and radiation dose for doses in the range 0-4 Gy. Mortality from radiation-induced heart disease usually occurs at least a decade after irradiation. Symptomatic heart disease might have a much shorter induction period, but little information about it is available at present. Subclinical vascular abnormalities have been observed within months of irradiation, via myocardial perfusion imaging studies, but little is known about the relationship between these and later overt heart disease. At present, few data relate heart dose and other specific characteristics of breast radiotherapy to cardiac outcome. Further information on these topics is needed to enable estimation of the cardiac risk, that is likely to arise from radiotherapy regimens in current use and from those being considered for future use. Such knowledge would facilitate radiotherapy treatment planning and enable a reduction in cardiac risk while maintaining the known benefit in terms of breast cancer mortality.

Cardiac Morbidity of Adjuvant Radiotherapy for Breast Cancer

Purpose

Adjuvant breast irradiation has been associated with an increase in cardiac mortality, because left-sided breast radiation can produce cardiac damage. The purpose of this study was to determine whether modern adjuvant radiotherapy is associated with increased risk of cardiac morbidity.

Patients and Methods

Data from the Surveillance, Epidemiology, and End Results–Medicare database were used for women who were diagnosed with nonmetastatic breast cancer from 1986 to 1993, had known disease laterality, underwent breast surgery, and received adjuvant radiotherapy. The Cox proportional-hazards model was used to compare patients with left- versus right-sided breast cancer for the end points of hospitalization with the following discharge diagnoses (International Classification of Diseases, 9th Revision codes): ischemic heart disease (410-414, 36.0, and 36.1), valvular heart disease (394-397, 424, 35), congestive heart failure (428, 402.01, 402.11, 402.91, and 425), and conduction abnormalities (426, 427, 37.7-37.8, and 37.94-37.99).

Results

Eight thousand three hundred sixty-three patients had left-sided breast cancer, and 7,907 had right-sided breast cancer. Mean follow-up was 9.5 years (range, 0 to 15 years). There were no significant differences in patients with left- versus right-sided cancers for hospitalization for ischemic heart disease (9.9% v 9.7%), valvular heart disease (2.9% v 2.8%), conduction abnormalities (9.7% v 9.6%), or heart failure (9.7% v 9.7%). The adjusted hazard ratio for left- versus right-sided breast cancer was 1.05 (95% CI, 0.94 to 1.16) for ischemic heart disease, 1.07 (95% CI, 0.89 to 1.30) for valvular heart disease, 1.07 (95% CI, 0.96 to 1.19) for conduction abnormalities, and 1.05 (95% CI, 0.95 to 1.17) for heart failure.

Conclusion

With up to 15 years of follow-up there were no significant differences in cardiac morbidity after radiation for left- versus right-sided breast cancer.

The incidence and functional consequences of RT-associated cardiac perfusion defects

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 prospective 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 99m 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.

Adjuvant radiotherapy for breast cancer: effects of longer follow-up

BACKGROUND AND PURPOSE

Recent and large trials of adjuvant radiotherapy for breast cancer have shown an overall survival benefit in favour of radiotherapy. However, with longer follow-up the late lethal toxicity of radiotherapy might reduce the overall survival benefits. In this paper we investigate more deeply this hypothesis.

PATIENTS AND METHODS

Overviews of the Early Breast Cancer Trialists' Collaborative Group provide uniform data on more than 50 unconfounded trials on adjuvant radiotherapy for early breast cancer. These data were published at regular intervals: 1987, 1990, 1995, and 2000. The odds ratios (death of any cause) were borrowed to compare the benefits of adjuvant radiotherapy between the early publications and the more mature data of the same trials. Statistical significance is calculated following logrank statistics. The comparison of odds ratios (radiotherapy versus surgery only) was done for the whole group of trials, for the older (patients accrual started in 1970 or earlier) and the more recent trials (patient accrual started after 1970), and for the large (>or=600 patients) and the small trials (<600 patients).

RESULTS

Comparison of early with more mature data reveals that the odds ratios for overall survival remain stable as data become more mature. The analyses of trials' age and trials' size, as predictors of overall survival benefit, indicate that these factors become statistically more significant with increasing maturity of the trials. In the large recent trials an overall survival benefit due to radiotherapy (odds reduction) of 10, 10, 12 and 13%, respectively P<0.3, 0.2, 0.005 and 0.00005 is found in the successive publications. The difference in survival benefit of radiotherapy between the group of large recent trials and group of old or small trials becomes more significant at the successive updates: 10 via 9% and 12 to 13% (odds reductions), with respectively P=0.2, 0.2, 0.004 and 0.00005.

CONCLUSIONS

These results support the hypothesis that the survival benefit in the recent trials is an inherent characteristic of the recent and large trials, not influenced by follow-up duration. The effect of radiotherapy as performed in the large recent trials is clinically and statistically significantly different from the effect of radiotherapy in the old or small trials. As a consequence, predictions based on pooled data including old radiotherapy trials should not be extrapolated to modern radiotherapy.

Irradiation of the heart during tangential breast treatment: a study within the START trial

Radiotherapy to the breast is often given as a component of the treatment for women with breast cancer. It has been shown to increase overall survival although an increase in cardiac mortality has also been noted. This study was undertaken as part of the START trial quality assurance programme to record and evaluate the cardiac dose using modern radiotherapy techniques. Departments randomizing patients into the START trial and who had CT facilities for planning breast patients were invited to take part. 62 patients were included. CT slices were taken at the level of the maximum heart depth and on the treatment field central axis. Each patient was planned in the normal way and the distributions were analysed by the quality assurance team at Mount Vernon Hospital. The maximum heart position was found to be inferior to the central axis used for breast planning for the majority of patients; mean position 2.3 cm inferior with a mean maximum heart depth of 0.55 cm. For 45% of patients the maximum heart dose was less than 50% of the prescribed dose. The study showed that the volume of irradiated cardiac tissue has decreased compared with earlier studies, and also highlighted the need to scan away from the central axis if the dose to cardiac tissue is to be assessed.

The clinical value of nuclear medicine in the assessment of irradiation-induced and anthracycline-associated cardiac damage

Two groups of patients, those treated for Hodgkin's disease and breast cancer, are particularly at risk of developing late myocardial damage, since radiotherapy (RT) techniques for both patient groups may include (large) parts of the heart, and adjuvant systemic therapy is frequently administered to these patients, in particular anthracycline-containing chemotherapy. Available literature on the monitoring and prediction of RT-induced and anthracycline-associated cardiac damage using nuclear medicine techniques is presented. Based on relevant studies, the risk of overall cardiac disease post-RT and overt congestive heart failure during anthracycline-containing chemotherapy is probably low. Conventional nuclear medicine imaging, i.e. myocardial perfusion scintigraphy, may be of complementary use to echocardiographical evaluation for routine follow-up after RT with modern techniques, in a subgroup of patients with known cardiovascular risk factors. Left ventricle ejection fraction (LVEF) measurements, as assessed by radionuclide angiography for the monitoring of anthracycline-associated cardiac injury, are not very sensitive and early detection will probably be enhanced by combining LVEF measurements with other cardiac function parameters. Also, it may be expected that nuclear medicine techniques using molecular radioligands will constitute an essential future step in the evaluation of subclinical cardiac injury afforded by the combined effect of RT and cardiotoxic chemotherapy.

Hypofractionated and accelerated radiotherapy with cytoprotection (HypoARC): a short, safe, and effective postoperative regimen for high-risk breast cancer patients

PURPOSE

Although the role of radiotherapy (RT) after mastectomy in reducing the local relapse rate is well established, its impact on overall survival is strongly questioned. Up to 70% of patients will not benefit from additional RT, and a "wait and see" policy is often adopted. Establishment of short, still safe, and effective RT regimens would render adjunctive radiotherapy more appealing. We evaluated the toxicity and efficacy of a Hypofractionated and intensively Accelerated RT regimen supported with amifostine Cytoprotection (HypoARC) in a cohort of 72 high-risk breast cancer patients treated with modified mastectomy or conservative surgery and FEC (5-fluorouracil/epirubicin/cyclophosphamide) chemotherapy.

PATIENTS AND METHODS

A high dose of amifostine, 1,000 mg, was given as a 5-min i.v. infusion before each of the 12 consecutive fractions of RT (4 x 3.5 Gy/fraction and 8 x 4 Gy/fraction, 1 fraction/day, 5 fractions/week). The breast or chest wall, as well as supraclavicular and axillary area, was included in the RT fields. The follow-up of patients ranged from 18 to 42 months (median, 28 months). Alkaline phosphatase (AF) expression was assessed immunohistochemically in normal and cancerous breast tissues.

RESULTS

Ninety-two percent of patients successfully completed the regimen, the only side effects being mild nausea and asthenia. In 7% of patients, amifostine was interrupted because of a rash/fever reaction. A dramatic reduction in acute skin toxicity was noted (p < 0.0001). Acute pneumonitis, as well as late toxicity in breast, chest wall, axillary, and lung tissue, was lower with the HypoARC regimen, although not significantly, than with the standard fractionation regimen used to treat two matched control cohorts. Both HypoARC and standard RT significantly reduce the local relapse rate (p < 0.0001), although the local relapse-free and overall survival times were marginally better for the HypoARC group of patients (p > 0.09). AF showed a mixed nuclear/cytoplasmic pattern of expression in the epithelial, endothelial, and stromal component of the normal breast and benign lesions, whereas an impressive loss of AF expression was noted in in situ and invasive breast cancer and tumoral stroma.

CONCLUSIONS

The HypoARC regimen is convenient for both patients and radiotherapy departments. The regimen is well tolerated and shows a significantly better profile in terms of early toxicity; a reduced rate of late sequel may be expected. The local relapse rate is as low as that expected from conventional RT. The absence of AF expression in cancer cells and tumoral stroma is probably a major reason for the selective protection of normal breast tissue by amifostine.

Cardiac and lung complication probabilities after breast cancer irradiation

PURPOSE

To assess for locoregional irradiation of breast cancer patients, the dependence of cardiac (cardiac mortality) and lung (radiation pneumonitis) complications on treatment technique and individual patient anatomy.

MATERIALS AND METHODS

Three-dimensional treatment planning was performed for 30 patients with left-sided breast cancer and various breast sizes. Two locoregional techniques (Techniques A and B) and a tangential field technique, including only the breast in the target volume, were planned and evaluated for each patient. In both locoregional techniques tangential photon fields were used to irradiate the breast. The internal mammary (IM)-medial supraclavicular (MS) lymph nodes were treated with an anterior mixed electron/photon field (Technique A) or with an obliquely incident mixed electron/photon IM field and an anterior electron/photon MS field (Technique B). The optimal IM and MS electron field dimensions and energies were chosen on the basis of the IM-MS lymph node target volume as delineated on CT-slices. The position of the tangential fields was adapted to match the IM-MS fields. Dose-volume histograms (DVHs) and normal tissue complication probabilities (NTCPs) for the heart and lung were compared for the three techniques. In the beam's eye view of the medial tangential fields the maximum distance of the heart contour to the posterior field border was measured; this value was scored as the Maximum Heart Distance.

RESULTS

The lymph node target volume receiving more than 85% of the prescribed dose was on average 99% for both locoregional irradiation techniques. The breast PTV receiving more than 95% of the prescribed dose was generally smaller using Technique A (mean: 90%, range: 69-99%) than using Technique B (mean: 98%, range: 82-100%) or for the tangential field technique (mean: 98%, range: 91-100%). NTCP values for excess cardiac mortality due to acute myocardial ischemia varied considerably between patients, with minimum and maximum values of 0.1 and 7.5% (Technique A), 0.1 and 5.8% (Technique B) and 0.0 and 6.1% (tangential tech.). The NTCP values were on average significantly higher (P<0.001) by 1.7% (Technique A) and 1.0% (Technique B) when locoregional breast irradiation was given, compared with irradiation of the left breast only. The NTCP values for the tangential field technique could be estimated using the Maximum Heart Distance. NTCP values for radiation pneumonitis were very low for all techniques; between 0.0 and 1.0%.

CONCLUSIONS

Technique B results in a good coverage of the breast and locoregional lymph nodes, while Technique A sometimes results in an underdosage of part of the target volume. Both techniques result in a higher probability of heart complications compared with tangential irradiation of the breast only. Irradiation toxicity for the lung is low in all techniques. The Maximum Heart Distance is a simple and useful parameter to estimate the NTCP values for cardiac mortality for tangential breast irradiation.

Surgery in breast cancer

This year (1999) has been filled with new information on the prevention of breast cancer and new literature trying to address some of the long-term adverse consequences of our surgical therapies. As the complexities of our therapies continue to increase at exponential rates, we now also have the ability to more accurately predict the consequences of both our therapeutic actions and our failure to act. Nowhere is this more evident than in the literature devoted to long-term consequences of treatment for breast cancer. As we are more successful in achieving our goals of increased survival from this dreaded disease, the future needs of these long-term survivors must play an ever-increasing role in our current management. Advances reported this year are laying down a new basis for efforts to improve the quality of life for breast cancer survivors.