Cardiac Risks of Breast-cancer Radiotherapy: A Contemporary View

Efficacity of Deep Inspiration Breath Hold and Intensity-Modulated Radiotherapy in Preventing Perfusion Defect for Left Sided Breast Cancer (EDIPE): A Prospective Cohort Study Protocol

Breast radiotherapy can lead to radiation-induced cardiac disease, particularly in left breast cancers. Recent studies have shown that subclinical cardiac lesions, such as myocardial perfusion deficits, may occur early after radiotherapy. The primary method for irradiating breast cancer, known as opposite tangential field radiotherapy, can cause the anterior interventricular coronary artery to receive a high dose of radiation during left breast irradiation. To explore alternative approaches that could reduce the risk of myocardial perfusion defects in patients with left breast cancer, we plan to conduct a prospective single-center study using a combination of deep inspiration breath hold radiotherapy and intensity modulated radiation therapy. The study will use stress and, if necessary, resting myocardial scintigraphy to assess myocardial perfusion. The trial aims to show that reducing the cardiac dose with these techniques can prevent the appearance of early (3-month) and medium-term (6- and 12-month) perfusion disorders.

Nuclear medicine imaging methods of radiation-induced cardiotoxicity

Breast cancer survival is significantly improved over the past decades due to major improvements in anti-tumor therapies and the implementation of regular screening, which leads to early detection of breast cancer. Therefore, it is of utmost importance to prevent patients from long-term side effects, including radiotherapy-induced cardiotoxicity. Radiotherapy may contribute to damage of myocardial structures on the cellular level, which eventually could result in various types of cardiovascular problems, including coronary artery disease and (non-)ischemic cardiomyopathy, leading to heart failure. These cardiac complications of radiotherapy are preceded by alterations in myocardial perfusion and blood flow. Therefore, early detection of these alterations is important to prevent the progression of these pathophysiological processes. Several radionuclide imaging techniques may contribute to the early detection of these changes. Single-Photon Emission Computed Tomography (SPECT) cameras can be used to create Multigated Acquisition scans in order to assess the left ventricular systolic and diastolic function. Furthermore, SPECT cameras are used for myocardial perfusion imaging with radiopharmaceuticals such as ^99mTc-sestamibi and ^99mTc-tetrofosmin. Accurate quantitative measurement of myocardial blood flow (MBF), can be performed by Positron Emission Tomography (PET), as the uptake of some of the tracers used for PET-based MBF measurement almost creates a linear relationship with MBF, resulting in very accurate blood flow quantification. Furthermore, there are PET and SPECT tracers that can assess inflammation and denervation of the cardiac sympathetic nervous system. Research over the past decades has mainly focused on the long-term development of left ventricular impairment and perfusion defects. Considering laterality of the breast cancer, some early studies have shown that women irradiated for left-sided breast cancer are more prone to cardiotoxic side effects than women irradiated for right-sided breast cancer. The left-sided radiation field in these trials, which predominantly used older radiotherapy techniques without heart-sparing techniques, included a larger volume of the heart and left ventricle, leading to increased unavoidable radiation exposure to the heart due to the close proximity of the radiation treatment volume. Although radiotherapy for breast cancer exposes the heart to incidental radiation, several improvements and technical developments over the last decades resulted in continuous reduction of radiation dose and volume exposure to the heart. In addition, radiotherapy reduces loco-regional tumor recurrences and death from breast cancer and improves survival. Therefore, in the majority of patients, the benefits of radiotherapy outweigh the potential very low risk of cardiovascular adverse events after radiotherapy. This review addresses existing nuclear imaging techniques, which can be used to evaluate (long-term) effects of radiotherapy-induced mechanical cardiac dysfunction and discusses the potential use of more novel nuclear imaging techniques, which are promising in the assessment of early signs of cardiac dysfunction in selected irradiated breast cancer patients.

Effect of radiotherapy on coronary arteries and heart in breast-conserving surgery: a dosimetric analysis

Background

There are certain risks of radiotherapy (RT), especially patients with left-sided breast cancer have a higher tendency to develop cardiac complications than the right-sided cancers. This study aims to perform a dosi-metric analysis the effect of RT on coronary arteries and heart in breast-conserving surgery.

Patients and methods

A total of 40 patients with early stage right and left-sided breast carcinomas (T1/T2 + N0) were randomly selected. RT was delivered to the entire breast, and tumor beds were boosted in these patients using tangential fields with computed tomography based planning. The doses for Left anterior descending coronary artery (LAD), left circumflex coronary artery (LCx), right ventricle (RV), left ventricle (LV), and heart were recorded and median values compared between groups.

Results

The highest mean of radiation dose in patients with left-sided breast cancer was to LAD 2402.48 ± 838.39 cGy, while the highest mean dose in right-sided breast cancer patients was to RV 130.18 ± 24.92. The highest maximum dose of radiotherapy was applied to heart at left-sided breast cancer patients as well as at right-sides prients. The mean V5 of the LV was 18.68% (6.89–31.69), mean V25 of the LV was 5.22% (0.45–16.54), mean V5 in bilateral ventricles was 23.73% (2.56–26.89), and mean V25 in bilateral ventricles 6.78% (0.63–13.63).

Conclusions

Especially in left-sided breast cancer, the most direct and best strategy to reduce and protect radiation-induced cardiac injury is to balance dose constraints between several high-dose regions of cardiac substructures and the mean heart dose.

BNP as a potential biomarker for cardiac damage of breast cancer after radiotherapy: a meta-analysis

BACKGROUND

To analyze whether BNP could be a potential biomarker for cardiac damage of breast cancer after radiotherapy.

METHODS

PubMed, Web of Science, ProQuest and Medline were searched using the key words "breast cancer" ("breast tumor", "breast neoplasm", or "breast carcinoma"), "brain natriuretic peptide" (or BNP) and "radiotherapy" (or "radiation therapy"). Four articles were selected and analyzed using the STATA 12.0 software package. The standard mean difference (SMD) and its standard error for BNP were calculated to assess the relationship between BNP and radiotherapy for breast cancer patients.

RESULTS

In total, 172 patients with breast cancer were identified. The pooled SMD was -0.233 (95% CI -1.113, -0.057). The pooled estimated SMD for all studies showed obvious significant difference (z = 3.99, P = .000). There was no publication bias.

CONCLUSIONS

This meta-analysis suggested that BNP could be a biomarker of cardiac damage at high heart absorbed doses according to radiotherapy, especially for left breast cancer patients.

Hybrid volumetric modulated arc therapy for whole breast irradiation: a dosimetric comparison of different arc designs

PURPOSE

To find an optimal arc design for hybrid volumetric modulated arc therapy (H-VMAT), a combination of conventional 3DCRT and VMAT plans for left-sided whole breast radiation therapy.

METHODS AND MATERIALS

A total of 26 left-sided early-stage breast cancer patients were selected for this study. To find the superior plan, H-VMAT with three different arc designs including, two partial arcs (2A), four partial arcs (4A) and four tangential arcs (TA) were created for each study case by combining 3DCRT and VMAT with 75% 3DCRT/25% VMAT dose proportion of prescription dose.

RESULTS

All H-VMAT plans achieved the expected target coverage. A higher conformity index and homogeneity index were achieved for 2A and 4A H-VMAT plans and significantly differ from TA H-VMAT (p < 0.003). The heart and ipsilateral lung dose parameters were comparable among all plans except heart V_40Gy which was significantly less in 4A H-VMAT plan (p < 0.05). The contralateral lung, contralateral breast, spinal cord, normal tissue doses and MU were significantly less in TA H-VMAT (p < 0.03). The beam-on time was significantly less in 2A H-VMAT (p < 0.0001).

CONCLUSION

2A and 4A H-VMAT techniques are effective in improving the PTV dosimetric parameters as well as reducing the OAR doses. Further, 2A H-VMAT delivers less MU and beam-on time compared to 4A H-VMAT.

Impact of radiotherapy on cardiovascular health of women with breast cancer

INTRODUCTION

This study aims to examine the impact of radiotherapy on the cardiovascular health of women diagnosed with breast cancer in the Waikato region in New Zealand.

METHODS

Women diagnosed with stage 0-III breast cancer and recorded in the Waikato Breast Cancer Registry were divided into two groups: a radiotherapy group and a no-radiotherapy group. Baseline characteristics and treatments were compared in the two groups. Kaplan-Meier survival analysis was performed to compare cardiovascular morbidity and mortality. Cox Proportional Hazard regression analysis was used to estimate the hazard ratio of radiotherapy on the risk of cardiovascular morbidity and mortality while adjusting for other factors.

RESULTS

A total of 3528 women were included in this study, with 2303 in the radiotherapy group and 1225 in the no-radiotherapy group. At 10-year follow-up, 11.7% of women in the radiotherapy group and 19.4% in the no-radiotherapy group experienced cardiovascular events. Only 2.3% of patients who received radiotherapy died of cardiovascular disease by 10 years compared to 7.0% in the no-radiotherapy group. After adjusting for clinically significant factors, there was unexplained reduced risk of developing cardiovascular disease in the radiotherapy group compared to the no-radiotherapy group (HR 0.73, 95% CI: 0.59-0.92). No significant difference was found in cardiovascular mortality between the two groups.

CONCLUSIONS

Radiotherapy appears less likely to be offered to patients at higher risk of cardiovascular disease. No evidence of increased risk of a cardiovascular event was found in the group of women with breast cancer treated with radiotherapy and current regimens appear safe. Traditional cardiovascular risk factors remain the main culprits in this setting. Clinicians should work with patients in managing these risk factors for optimal results.

Cardiac Structure Injury After Radiotherapy for Breast Cancer: Cross-Sectional Study With Individual Patient Data

Purpose Incidental cardiac irradiation can cause cardiac injury, but little is known about the effect of radiation on specific cardiac segments. Methods For 456 women who received breast cancer radiotherapy between 1958 and 2001 and then later experienced a major coronary event, information was obtained on the radiotherapy regimen they received and on the location of their cardiac injury. For 414 women, all with documented location of left ventricular (LV) injury, doses to five LV segments were estimated. For 133 women, all with documented location of coronary artery disease with ≥ 70% stenosis, doses to six coronary artery segments were estimated. For each segment, numbers of women with left-sided and right-sided breast cancer were compared. Results Of women with LV injury, 243 had left-sided breast cancer and 171 had right-sided breast cancer (ratio of left v right, 1.42; 95% CI, 1.17 to 1.73), reflecting the higher typical LV radiation doses in left-sided cancer (average dose left-sided, 8.3 Gy; average dose right-sided, 0.6 Gy; left minus right dose difference, 7.7 Gy). For individual LV segments, the ratios of women with left- versus right-sided radiotherapy were as follows: inferior, 0.94 (95% CI, 0.70 to 1.25); lateral, 1.42 (95% CI, 1.04 to 1.95); septal, 2.09 (95% CI, 1.37 to 3.19); anterior, 1.85 (95% CI, 1.39 to 2.46); and apex, 4.64 (95% CI, 2.42 to 8.90); corresponding left-minus-right dose differences for these segments were 2.7, 4.9, 7.2, 10.4, and 21.6 Gy, respectively ( Ptrend < .001). For women with coronary artery disease, the ratios of women with left- versus right-radiotherapy for individual coronary artery segments were as follows: right coronary artery proximal, 0.48 (95% CI, 0.26 to 0.91); right coronary artery mid or distal, 1.69 (95% CI, 0.85 to 3.36); circumflex proximal, 1.46 (95% CI, 0.72 to 2.96); circumflex distal, 1.11 (95% CI, 0.45 to 2.73); left anterior descending proximal, 1.89 (95% CI, 1.07 to 3.34); and left anterior descending mid or distal, 2.33 (95% CI, 1.19 to 4.59); corresponding left-minus-right dose differences for these segements were -5.0, -2.5, 1.6, 3.5, 9.5, and 38.8 Gy ( Ptrend = .002). Conclusion For individual LV and coronary artery segments, higher radiation doses were strongly associated with more frequent injury, suggesting that all segments are sensitive to radiation and that doses to all segments should be minimized.

Hybrid volumetric modulated arc therapy for chest wall irradiation: For a good plan, get the right mixture

PURPOSE

To find the optimal dose weighting for hybrid volumetric modulated arc therapy (H-VMAT), a combination of conventional 3DCRT and VMAT plans for left sided chest wall and supraclavicular radiation therapy.

METHODS & MATERIALS

20 left-sided breast cancer patients who received adjuvant radiotherapy were considered for this study. To find the optimal weighting, 5 H-VMAT plans were generated for each study case by combining different dose proportions of 3DCRT and VMAT plans including: 90% 3DCRT/10% VMAT, 80% 3DCRT/20% VMAT, 70% 3DCRT/30% VMAT, 60% 3DCRT/40% VMAT, 50% 3DCRT/50% VMAT. Further field-in-field, optimal H-VMAT and VMAT alone plans were compared.

RESULTS

All H-VMAT plans achieved the expected target coverage. A higher conformity index was achieved for 50% 3DCRT/50% VMAT plan, while better homogeneity index was achieved for 80% 3DCRT/20% VMAT plan. Mean and low doses were less in 90% 3DCRT/10% VMAT plan. Compared with other proportions, 80% 3DCRT/20% VMAT and 70% 3DCRT/30% VMAT weighted H-VMAT plans achieved balanced results for PTVs and OARs.

CONCLUSION

The optimal dose mixture for H-VMAT technique is 70% to 80% for 3DCRT and 20% to 30% for VMAT. The optimal H-VMAT achieved balanced results for the PTVs and OARs compared with field-in-field and VMAT alone plans.

Dosimetric comparison of IMRT versus 3DCRT for post-mastectomy chest wall irradiation

Purpose

To compare the dose distribution of three-dimensional conformal radiation therapy (3DCRT) with intensity-modulated radiation therapy (IMRT) for post-mastectomy radiotherapy (PMRT) to left chest wall.

Materials and Methods

One hundred and seven patients were randomised for PMRT in 3DCRT group (n = 64) and IMRT group (n = 43). All patients received 50 Gy in 25 fractions. Planning target volume (PTV) parameters—D_near-max (D₂), D_near-min (D₉₈), D_mean, V₉₅, and V₁₀₇—homogeneity index (HI), and conformity index (CI) were compared. The mean doses of lung and heart, percentage volume of ipsilateral lung receiving 5 Gy (V₅), 20 Gy (V₂₀), and 55 Gy (V₅₅) and that of heart receiving 5 Gy (V₅), 25 Gy (V₂₅), and 45 Gy (V₄₅) were extracted from dose-volume histograms and compared.

Results

PTV parameters were comparable between the two groups. CI was significantly improved with IMRT (1.127 vs. 1.254, p < 0.001) but HI was similar (0.094 vs. 0.096, p = 0.83) compared to 3DCRT. IMRT in comparison to 3DCRT significantly reduced the high-dose volumes of lung (V₂₀, 22.09% vs. 30.16%; V₅₅, 5.16% vs. 10.27%; p < 0.001) and heart (V₂₅, 4.59% vs. 9.19%; V₄₅, 1.85% vs. 7.09%; p < 0.001); mean dose of lung and heart (11.39 vs. 14.22 Gy and 4.57 vs. 8.96 Gy, respectively; p < 0.001) but not the low-dose volume (V₅ lung, 61.48% vs. 51.05%; V₅ heart, 31.02% vs. 23.27%; p < 0.001).

conclusions

For left sided breast cancer, IMRT significantly improves the conformity of plan and reduce the mean dose and high-dose volumes of ipsilateral lung and heart compared to 3DCRT, but 3DCRT is superior in terms of low-dose volume.

Oncolytic Virotherapy for Breast Cancer Treatment

Breast cancer continues to be a leading cause of mortality among women. While at an early stage, localized breast cancer is easily treated; however, advanced stages of disease continue to carry a high mortality rate. The discrepancy in treatment success highlights that current treatments are insufficient to treat advanced-stage breast cancer. As new and improved treatments have been sought, one therapeutic approach has gained considerable attention. Oncolytic viruses are uniquely capable of targeting cancer cells through intrinsic or engineered means. They come in many forms, mainly from four major virus groups as defined by the Baltimore classification system. These vectors can target and kill cancer cells, and even stimulate immunotherapeutic effects in patients. This review discusses not only individual oncolytic viruses pursued in the context of breast cancer treatment but also the emergence of combination therapies with current or new therapies, which has become a particularly promising strategy for treatment of breast cancer. Overall, oncolytic virotherapy is a promising strategy for increased treatment efficacy for advanced breast cancer and consequently provides a unique platform for personalized treatments in patients.

Different Sequences of Fractionated Low-Dose Proton and Single Iron-Radiation-Induced Divergent Biological Responses in the Heart

Deep-space travel presents risks of exposure to ionizing radiation composed of a spectrum of low-fluence protons (¹H) and high-charge and energy (HZE) iron nuclei (e.g., ⁵⁶Fe). When exposed to galactic cosmic rays, each cell in the body may be traversed by ¹H every 3-4 days and HZE nuclei every 3-4 months. The effects of low-dose sequential fractionated ¹H or HZE on the heart are unknown. In this animal model of simulated ionizing radiation, middle-aged (8-9 months old) male C57BL/6NT mice were exposed to radiation as follows: group 1, nonirradiated controls; group 2, three fractionated doses of 17 cGy ¹H every other day (¹H × 3); group 3, three fractionated doses of 17 cGy ¹H every other day followed by a single low dose of 15 cGy ⁵⁶Fe two days after the final ¹H dose (¹H × 3 + ⁵⁶Fe); and group 4, a single low dose of 15 cGy ⁵⁶Fe followed (after 2 days) by three fractionated doses of 17 cGy ¹H every other day (⁵⁶Fe + ¹H × 3). A subgroup of mice from each group underwent myocardial infarction (MI) surgery at 28 days postirradiation. Cardiac structure and function were assessed in all animals at days 7, 14 and 28 after MI surgery was performed. Compared to the control animals, the treatments that groups 2 and 3 received did not induce negative effects on cardiac function or structure. However, compared to all other groups, the animals in group 4, showed depressed left ventricular (LV) functions at 1 month with concomitant enhancement in cardiac fibrosis and induction of cardiac hypertrophy signaling at 3 months. In the irradiated and MI surgery groups compared to the control group, the treatments received by groups 2 and 4 did not induce negative effects at 1 month postirradiation and MI surgery. However, in group 3 after MI surgery, there was a 24% increase in mortality, significant decreases in LV function and a 35% increase in post-infarction size. These changes were associated with significant decreases in the angiogenic and cell survival signaling pathways. These data suggest that fractionated doses of radiation induces cellular and molecular changes that result in depressed heart functions both under basal conditions and particularly after myocardial infarction.

Radiation dose distribution in functional heart regions from tangential breast cancer radiotherapy

BACKGROUND AND PURPOSE

To analyze the distribution of individually-determined radiation dose to the heart and its functional sub-structures after radiotherapy in breast cancer patients treated in Germany during 1998-2008.

MATERIAL AND METHODS

We obtained electronic treatment planning records for 769 female breast cancer patients treated with megavoltage tangential field radiotherapy. All dose distributions were re-calculated using Eclipse with the anisotropic analytical algorithm (AAA) for photon fields, and the electron Monte Carlo algorithm for electron boost fields. Based on individual dose volume histograms for the complete heart and several functional sub-structures, we estimated various dose measures in patient groups.

RESULTS

Mean heart dose spanned a range of 0.9-19.1Gy for left-sided radiotherapy and 0.3-11.6Gy for right-sided radiotherapy. Average (median) mean heart dose was 4.6Gy (3.7Gy) for left-sided radiotherapy, and 1.7Gy (1.4Gy) for right-sided RT. With left-sided radiotherapy, 66% of the patients had 2cm(3) of the complete heart exposed to at least 40Gy. Younger age, higher body mass index, tumor location in a medial quadrant, and presence of a parasternal field were also associated with higher heart dose.

CONCLUSION

Tumor location and treatment choices influence cardiac dose with complex interactions. There is considerable variability in heart dose, with dose metrics of different cardiac sub-structures showing different patterns in their dependency on external influences. Dose-response analysis of late cardiac effects after radiotherapy requires detailed individual dosimetry.

Particle Radiation-Induced Nontargeted Effects in Bone-Marrow-Derived Endothelial Progenitor Cells

Bone-marrow- (BM-) derived endothelial progenitor cells (EPCs) are critical for endothelial cell maintenance and repair. During future space exploration missions astronauts will be exposed to space irradiation (IR) composed of a spectrum of low-fluence protons ((1)H) and high charge and energy (HZE) nuclei (e.g., iron-(56)Fe) for extended time. How the space-type IR affects BM-EPCs is limited. In media transfer experiments in vitro we studied nontargeted effects induced by (1)H- and (56)Fe-IR conditioned medium (CM), which showed significant increase in the number of p-H2AX foci in nonirradiated EPCs between 2 and 24 h. A 2-15-fold increase in the levels of various cytokines and chemokines was observed in both types of IR-CM at 24 h. Ex vivo analysis of BM-EPCs from single, low-dose, full-body (1)H- and (56)Fe-IR mice demonstrated a cyclical (early 5-24 h and delayed 28 days) increase in apoptosis. This early increase in BM-EPC apoptosis may be the effect of direct IR exposure, whereas late increase in apoptosis could be a result of nontargeted effects (NTE) in the cells that were not traversed by IR directly. Identifying the role of specific cytokines responsible for IR-induced NTE and inhibiting such NTE may prevent long-term and cyclical loss of stem and progenitors cells in the BM milieu.

A novel technique for image-guided local heart irradiation in the rat

In radiotherapy treatment of thoracic, breast and chest wall tumors, the heart may be included (partially or fully) in the radiation field. As a result, patients may develop radiation-induced heart disease (RIHD) several years after exposure to radiation. There are few methods available to prevent or reverse RIHD and the biological mechanisms remain poorly understood. In order to further study the effects of radiation on the heart, we developed a model of local heart irradiation in rats using an image-guided small animal conformal radiation therapy device (SACRTD) developed at our institution. First, Monte Carlo based simulations were used to design an appropriate collimator. EBT-2 films were used to measure relative dosimetry, and the absolute dose rate at the isocenter was measured using the AAPM protocol TG-61. The hearts of adult male Sprague-Dawley rats were irradiated with a total dose of 21 Gy. For this purpose, rats were anesthetized with isoflurane and placed in a custom-made vertical rat holder. Each heart was irradiated with a 3-beam technique (one AP field and 2 lateral fields), with each beam delivering 7 Gy. For each field, the heart was visualized with a digital flat panel X-ray imager and placed at the isocenter of the 1.8 cm diameter beam. In biological analysis of radiation exposure, immunohistochemistry showed γH2Ax foci and nitrotyrosine throughout the irradiated hearts but not in the lungs. Long-term follow-up of animals revealed histopathological manifestations of RIHD, including myocardial degeneration and fibrosis. The results demonstrate that the rat heart irradiation technique using the SACRTD was successful and that surrounding untargeted tissues were spared, making this approach a powerful tool for in vivo radiobiological studies of RIHD. Functional and structural changes in the rat heart after local irradiation are ongoing.

Cardiovascular risks associated with low dose ionizing particle radiation

Previous epidemiologic data demonstrate that cardiovascular (CV) morbidity and mortality may occur decades after ionizing radiation exposure. With increased use of proton and carbon ion radiotherapy and concerns about space radiation exposures to astronauts on future long-duration exploration-type missions, the long-term effects and risks of low-dose charged particle irradiation on the CV system must be better appreciated. Here we report on the long-term effects of whole-body proton (¹H; 0.5 Gy, 1 GeV) and iron ion (⁵⁶Fe; 0.15 Gy, 1GeV/nucleon) irradiation with and without an acute myocardial ischemia (AMI) event in mice. We show that cardiac function of proton-irradiated mice initially improves at 1 month but declines by 10 months post-irradiation. In AMI-induced mice, prior proton irradiation improved cardiac function restoration and enhanced cardiac remodeling. This was associated with increased pro-survival gene expression in cardiac tissues. In contrast, cardiac function was significantly declined in ⁵⁶Fe ion-irradiated mice at 1 and 3 months but recovered at 10 months. In addition, ⁵⁶Fe ion-irradiation led to poorer cardiac function and more adverse remodeling in AMI-induced mice, and was associated with decreased angiogenesis and pro-survival factors in cardiac tissues at any time point examined up to 10 months. This is the first study reporting CV effects following low dose proton and iron ion irradiation during normal aging and post-AMI. Understanding the biological effects of charged particle radiation qualities on the CV system is necessary both for the mitigation of space exploration CV risks and for understanding of long-term CV effects following charged particle radiotherapy.

Sector Resection With or Without Postoperative Radiotherapy for Stage I Breast Cancer: 20-Year Results of a Randomized Trial

Purpose

To investigate how radiotherapy (XRT) adds to tumor control using a standardized surgical technique with meticulous control of surgical margins in a randomized trial with 20 years of follow-up.

Patients and Methods

Three hundred eighty-one women with pT1N0 breast cancer were randomly assigned to sector resection with (XRT group) or without (non-XRT group) postoperative radiotherapy to the breast. With follow-up through 2010, we estimated cumulative proportion of recurrence, breast cancer death, and all-cause mortality.

Results

The cumulative probability of a first breast cancer event of any type after 20 years was 30.9% in the XRT group and 45.1% in the non-XRT group (hazard ratio [HR], 0.58; 95% CI, 0.41 to 0.82). The benefit of radiotherapy was achieved within the first 5 years. After 20 years, 50.4% of the women in the XRT group died compared with 54.0% in the non-XRT group (HR, 0.92; 95% CI, 0.71 to 1.19). The cumulative probability of contralateral cancer or death as a result of cancer other than breast cancer was 27.1% in the XRT group and 24.9% in the non-XRT group (HR, 1.17; 95% CI, 0.77 to 1.77). In an anticipated low-risk group, the cumulative incidence of first breast cancer of any type was 24.8% in the XRT group and 36.1% in the non-XRT group (HR, 0.61; 95% CI, 0.35 to 1.07).

Conclusion

Radiotherapy protects against recurrences during the first 5 years of follow-up, indicating that XRT mainly eradicates undetected cancer foci present at primary treatment. The similar rate of recurrences beyond 5 years in the two groups indicates that late recurrences are new tumors. There are subgroups with clinically relevant differences in risk.

Can the risk of secondary cancer induction after breast conserving therapy be reduced using intraoperative radiotherapy (IORT) with low-energy x-rays?

BACKGROUND

Radiation induced secondary cancers are a rare but severe late effect after breast conserving therapy. Intraoperative radiotherapy (IORT) is increasingly used during breast conserving surgery. The purpose of this analysis was to estimate secondary cancer risks after IORT compared to other modalities of breast radiotherapy (APBI - accelerated partial breast irradiation, EBRT - external beam radiotherapy).

METHODS

Computer-tomography scans of an anthropomorphic phantom were acquired with an INTRABEAM IORT applicator (diameter 4 cm) in the outer quadrant of the breast and transferred via DICOM to the treatment planning system. Ipsilateral breast, contralateral breast, ipsilateral lung, contralateral lung, spine and heart were contoured. An INTRABEAM source (50 kV) was defined with the tip of the drift tube at the center of the spherical applicator. A dose of 20 Gy at 0 mm depth from the applicator surface was prescribed for IORT and 34 Gy (5 days × 2 × 3.4 Gy) at 10 mm depth for APBI. For EBRT a total dose of 50 Gy in 2 Gy fractions was planned using two tangential fields with wedges. The mean and maximal doses, DVHs and volumes receiving more than 0.1 Gy and 4 Gy of organs at risk (OAR) were calculated and compared. The life time risk for secondary cancers was estimated according to NCRP report 116.

RESULTS

IORT delivered the lowest maximal doses to contralateral breast (< 0.3 Gy), ipsilateral (1.8 Gy) and contralateral lung (< 0.3 Gy), heart (1 Gy) and spine (< 0.3 Gy). In comparison, maximal doses for APBI were 2-5 times higher. EBRT delivered a maximal dose of 10.4 Gy to the contralateral breast and 53 Gy to the ipsilateral lung. OAR volumes receiving more than 4 Gy were 0% for IORT, < 2% for APBI and up to 10% for EBRT (ipsilateral lung). The estimated risk for secondary cancer in the respective OAR is considerably lower after IORT and/or APBI as compared to EBRT.

CONCLUSIONS

The calculations for maximal doses and volumes of OAR suggest that the risk of secondary cancer induction after IORT is lower than compared to APBI and EBRT.

Myocardial perfusion imaging with (99 m)Tc-tetrofosmin SPECT in breast cancer patients that received postoperative radiotherapy: a case-control study

Purpose

To evaluate the cardiac toxicity of radiotherapy (RT) in breast cancer (BC) patients employing myocardial perfusion imaging (MPI) with Tc-99 m Tetrofosmin - single photon emission computer tomography (T-SPECT).

Materials and methods

We studied 46 BC female patients (28 patients with left and 18 patients with right BC) treated with postoperative RT compared to a control group of 85 age-matched females. The median time of RT to SPECT was 40 months (6-263).

Results

Abnormalities in the summed stress score (SSS) were found in 54% of left BC patients, 44.4% of right BC patients, and 32.9% of controls. In left BC patients there were significantly more SSS abnormalities compared to controls (4.0 ± 3.5 vs 2.6 ± 2.0, p = 0.05) and possible trend of increased abnormalities of right BC patients (3.7 ± 3.0 vs 2.6 ± 2.0, p = 0.14). Multiple regression analysis showed more abnormalities in the MPI of left BC patients compared to controls (SSS, p = 0.0001); Marginal toxicity was also noted in right BC patients (SSS, p = 0.045). No additional toxicity was found in patients that received adjuvant cardiotoxic chemotherapy. All T-SPECT abnormalities were clinically silent.

Conclusion

The study suggests that radiation therapy to BC patients result in MPI abnormalities but without apparent clinical consequences.

Omission of radiation therapy after breast-conserving surgery in the United States: a population-based analysis of clinicopathologic factors

BACKGROUND

Radiation therapy (RT) after breast-conserving surgery (BCS) is associated with a significant reduction in ipsilateral breast tumor recurrence and breast cancer mortality rates in patients with early stage breast cancer. The authors of this report sought to determine which patients with breast cancer do not receive RT after BCS in the United States.

METHODS

The Surveillance, Epidemiology, and End Results registry was used to determine the rates of RT after BCS for women with stage I through III breast cancer in the United States from 1992 through 2007. A multivariate analysis was performed to identify independent predictors of omission of RT.

RESULTS

In total, 294,254 patients with invasive, nonmetastatic breast cancer were identified who underwent surgery from 1992 through 2007. Most patients (57%) underwent BCS; among those, 21.1% did not receive RT after BCS. The omission of RT increased significantly from 1992 (15.5%) to 2007 (25%). The receipt of RT also decreased significantly for patients with increased cancer stage, age <55 years, high-grade tumors, large tumors, positive or untested lymph node status, African American or Hispanic race, and negative or unknown estrogen receptor status. Significant geographic variation was observed in the rates of RT after BCS.

CONCLUSIONS

The omission of RT after BCS was more common in recent years, especially among women who had an increased risk of breast cancer recurrence. This trend represents a serious health care concern because of the potential increased risk of local recurrence and breast cancer mortality.

Long-term safety of radiotherapy and breast cancer laterality in older survivors

BACKGROUND

Although adjuvant radiotherapy (RT) following surgery for breast cancer improves overall survival, controversy exists about its long-term adverse impact on cardiovascular health in older survivors.

AIM

To determine whether incident cardiovascular disease (CVD) is associated with RT and whether tumor laterality modifies this association.

METHODS

Women aged 65+ years diagnosed with stage I and II breast cancer between 1990 and 1994 were identified from three health plans. Women were followed through CVD outcomes, health plan disenrollment, death, or study end (December 31, 2004). The main independent variable was RT use. Adjusted HRs and 95% CIs were estimated using Cox proportional hazards models with time-dependent tamoxifen and RT use status. We adjusted for age, race, stage, estrogen receptor/progesterone receptor, hypertension, and diabetes.

RESULTS

In the full cohort (N = 806), RT was not associated with greater risk of CVD (maximum follow-up was 14 years). However, within the RT-exposed group (N = 340), women treated for left-side breast cancer had a significant increased risk of CVD outcomes (HR = 1.53, 95% CI: 1.06-2.21) compared with women with right-sided tumors.

CONCLUSION

Laterality is critical to understanding the effect of RT on CVD. Studies of more contemporary cohorts of women treated with RT should incorporate this variable to determine whether the risk persists with refinements in the dosing and delivery of RT.

IMPACT

As some irradiation to the heart is unavoidable even with refined modern RT techniques, continued effort is required to minimize such exposures, especially in older women with left-sided tumors.

Evaluation of dose to cardiac structures during breast irradiation

OBJECTIVE

Adjuvant radiotherapy for breast cancer can lead to late cardiac complications. The highest radiation doses are likely to be to the anterior portion of the heart, including the left anterior descending coronary artery (LAD). The purpose of this work was to assess the radiation doses delivered to the heart and the LAD in respiration-adapted radiotherapy of patients with left-sided breast cancer.

METHODS

24 patients referred for adjuvant radiotherapy after breast-conserving surgery for left-sided lymph node positive breast cancer were evaluated. The whole heart, the arch of the LAD and the whole LAD were contoured. The radiation doses to all three cardiac structures were evaluated.

RESULTS

For 13 patients, the plans were acceptable based on the criteria set for all 3 contours. For seven patients, the volume of heart irradiated was well below the set clinical threshold whereas a high dose was still being delivered to the LAD. In 1 case, the dose to the LAD was low while 19% of the contoured heart volume received over 20 Gy. In five patients, the dose to the arch LAD was relatively low while the dose to the whole LAD was considerably higher.

CONCLUSION

This study indicates that it is necessary to assess the dose delivered to the whole heart as well as to the whole LAD when investigating the acceptability of a breast irradiation treatment. Assessing the dose to only one of these structures could lead to excessive heart irradiation and thereby increased risk of cardiac complications for breast cancer radiotherapy patients.

Potential targets for intervention in radiation-induced heart disease

Radiotherapy of thoracic and chest wall tumors, if all or part of the heart was included in the radiation field, can lead to radiation-induced heart disease (RIHD), a late and potentially severe side effect. RIHD presents clinically several years after irradiation and manifestations include accelerated atherosclerosis, pericardial and myocardial fibrosis, conduction abnormalities, and injury to cardiac valves. The pathogenesis of RIHD is largely unknown, and a treatment is not available. Hence, ongoing pre-clinical studies aim to elucidate molecular and cellular mechanisms of RIHD. Here, an overview of recent pre-clinical studies is given, and based on the results of these studies, potential targets for intervention in RIHD are discussed.

Tangential beam IMRT versus tangential beam 3D-CRT of the chest wall in postmastectomy breast cancer patients: a dosimetric comparison

Background

This study evaluates the dose distribution of reversed planned tangential beam intensity modulated radiotherapy (IMRT) compared to standard wedged tangential beam three-dimensionally planned conformal radiotherapy (3D-CRT) of the chest wall in unselected postmastectomy breast cancer patients

Methods

For 20 unselected subsequent postmastectomy breast cancer patients tangential beam IMRT and tangential beam 3D-CRT plans were generated for the radiotherapy of the chest wall. The prescribed dose was 50 Gy in 25 fractions. Dose-volume histograms were evaluated for the PTV and organs at risk. Parameters of the dose distribution were compared using the Wilcoxon matched pairs test.

Results

Tangential beam IMRT statistically significantly reduced the ipsilateral mean lung dose by an average of 21% (1129 cGy versus 1437 cGy). In all patients treated on the left side, the heart volume encompassed by the 70% isodose line (V70%; 35 Gy) was reduced by an average of 43% (5.7% versus 10.6%), and the mean heart dose by an average of 20% (704 cGy versus 877 cGy). The PTV showed a significantly better conformity index with IMRT; the homogeneity index was not significantly different.

Conclusions

Tangential beam IMRT significantly reduced the dose-volume of the ipsilateral lung and heart in unselected postmastectomy breast cancer patients.

Comparison between intensity modulated radiotherapy (IMRT) and 3D tangential beams technique used in patients with early-stage breast cancer who received breast-conserving therapy

BACKGROUND

The most often found complications in patients with breast cancer who received radiotherapy are cardiac and pulmonary function disorders and development of second malignancies.

AIM

To compare the intensity modulated radiotherapy with the 3D tangential beams technique in respect of dose distribution in target volume and critical organs they generate in patients with early-stage breast cancer who received breast-conserving therapy.

MATERIALS AND METHODS

A dosimetric analysis was performed to assess the three radiotherapy techniques used in each of 10 consecutive patients with early-stage breast cancer treated with breast-conserving therapy. Radiotherapy was planned with the use of all the three techniques: 3D tangential beams with electron boost, IMRT with electron boost, and intensity modulated radiotherapy with simultaneous integrated boost.

RESULTS

The use of the IMRT techniques enables more homogenous dose distribution in target volume. The range of mean and median dose to the heart and lung was lower with the IMRT techniques in comparison to the 3D tangential beams technique. The range of mean dose to the heart amounted to 0.3-3.5 Gy for the IMRT techniques and 0.4-4.3 for the tangential beams technique. The median dose to the lung on the irradiated side amounted to 4.9-5 Gy for the IMRT techniques and 5.6 Gy for the 3D tangential beams technique.

CONCLUSION

The application of the IMRT techniques in radiotherapy patients with early-stage breast cancer allows to obtain more homogenous dose distribution in target volume, while permitting to reduce the dose to critical organs.

Effect of nodal irradiation and fraction size on cardiac and cerebrovascular mortality in women with breast cancer treated with local and locoregional radiotherapy

PURPOSE

To determine whether the adjuvant breast cancer radiation volume or fraction size (>2 Gy vs. ≤2 Gy) affected the risk of fatal cardiac or cerebrovascular (CCV) events and to determine whether the addition of regional radiotherapy (RT) increased the risk of fatal cerebrovascular events compared with breast/chest wall RT alone.

METHODS AND MATERIALS

Overall survival was compared for patients receiving breast/chest wall RT alone or breast/chest wall plus regional node RT (BRCW+NRT) in a population-based cohort of women with early-stage breast cancer who had undergone RT between 1990 and 1996. The effect of laterality, age, systemic therapy, radiation volume, and fraction size on the risk of fatal CCV events was analyzed using a competing risk method.

RESULTS

A total of 4,929 women underwent adjuvant RT. The median follow-up was 11.7 years. BRCW+NRT was associated with an increased risk of CCV death at 12 years (5% for BRCW+NRT vs. 3.5% for breast/chest wall RT alone; p = .004), but the fraction size was not (3.92% for a fraction size >2 Gy vs. 3.54% for a fraction size <2 Gy; p = .83). The 12-year absolute risk of death from stroke alone did not differ for either radiation volume (1.17% for BRCW+NRT vs. 0.8% for breast/chest wall RT alone; p = .22) or fraction size (p = .59).

CONCLUSION

Regional RT was associated with a small (1.5% at 12 years), but statistically significant, increased risk of death from a CCV event. The addition of regional RT did not significantly increase the risk of death from stroke, although the number of events was small. An increased fraction size was not significantly associated with a greater risk of fatal CCV events. These data support the continued use of hypofractionated adjuvant regional RT.

Long-term results of hypofractionated radiation therapy for breast cancer

BACKGROUND

The optimal fractionation schedule for whole-breast irradiation after breast-conserving surgery is unknown.

METHODS

We conducted a study to determine whether a hypofractionated 3-week schedule of whole-breast irradiation is as effective as a 5-week schedule. Women with invasive breast cancer who had undergone breast-conserving surgery and in whom resection margins were clear and axillary lymph nodes were negative were randomly assigned to receive whole-breast irradiation either at a standard dose of 50.0 Gy in 25 fractions over a period of 35 days (the control group) or at a dose of 42.5 Gy in 16 fractions over a period of 22 days (the hypofractionated-radiation group).

RESULTS

The risk of local recurrence at 10 years was 6.7% among the 612 women assigned to standard irradiation as compared with 6.2% among the 622 women assigned to the hypofractionated regimen (absolute difference, 0.5 percentage points; 95% confidence interval [CI], -2.5 to 3.5). At 10 years, 71.3% of women in the control group as compared with 69.8% of the women in the hypofractionated-radiation group had a good or excellent cosmetic outcome (absolute difference, 1.5 percentage points; 95% CI, -6.9 to 9.8).

CONCLUSIONS

Ten years after treatment, accelerated, hypofractionated whole-breast irradiation was not inferior to standard radiation treatment in women who had undergone breast-conserving surgery for invasive breast cancer with clear surgical margins and negative axillary nodes. (ClinicalTrials.gov number, NCT00156052.)

[Radiation therapy in elderly patients]

Cancer is a disease that predominantly occurs in older patients who represent a quarter of the population in western countries. Numerous types of cancer are observed in elderly people. Radiotherapy is one of the most powerful treatment against cancer. Most of published studies have demonstrated feasibility of radiotherapy in curative or palliative intent whatever cancer types are considered. Complete geriatric assessment and a multidisciplinary approach are the key points. The purpose of this review is to highlight sights of radiation oncology specifically related to aging. Particular emphasis is placed on logistic and technical aspects of radiation. Special techniques are also reviewed that have particular relevance to the treatment of the elderly.

The potential clinical advantages of charged particle radiotherapy using protons or light ions

The increasing use of charged particle radiotherapy (CPT) in many countries will require British oncologists to establish their personal viewpoints on this subject in order to advise their patients regarding the merits or otherwise of obtaining such treatment abroad. This paper covers the advantages and some disadvantages of CPT in many anatomical locations on the basis of the achievable dose distributions as a consequence of the Bragg peak effect. The advantages in terms of normal tissue effects should follow the reduction of tissue volumes exposed to low/moderate dose: significant reductions in acute tissue effects are expected and experienced. For late reacting tissues, the predicted benefits are in the reduction of chronic low-grade symptoms and so improving the quality of life. For tumour control, dose escalation beyond what is achievable with X-ray therapy is possible only for some tumour types. Also, some tumours not presently treated by X-rays can be treated by CPT instead of radical surgery. Many of the available publications about CPT are at 'proof of principle' stage, as the treatment technique continues to be optimised: this is a similar situation to mega-voltage radiotherapy around 50 years ago. Oncologists in the UK need to familiarise themselves with CPT dose distributions, continually educate themselves by following the results of clinical studies as these emerge with time and hopefully visit CPT centres for direct experience.

Effectiveness of radiotherapy in myxoid sarcomas is associated with a dense vascular pattern

PURPOSE

Surgery and adjuvant radiotherapy (RT) have long been the standard treatment for most deep-seated sarcomas; however, since the randomized trial from the National Cancer Institute of Canada, which described similar local control for pre- vs. postoperative RT, both modalities are now widely accepted. As a group, sarcomas are classified as radiation resistant. The subgroup of myxoid liposarcoma (MLS), a sarcoma with a typical vascular crow's feet pattern, is highly radiosensitive, but a mechanism for this phenomenon is unknown. Here we describe our results with preoperative RT and propose a mechanism explaining the high sensitivity based on the distinctive vascularization pattern of MLS.

METHODS AND MATERIALS

Between 2002 and 2006, 31 sarcoma patients, including 10 with MLS, underwent preoperative RT at our institute. Resected specimens were histologically evaluated, focusing on classification, grade, and vascularization patterns.

RESULTS

Twenty sarcomas showed more than 80% pathologic response after preoperative RT. A pathologic complete response was found in all "pure" MLS specimens after preoperative RT (n = 8). There were no pathologic complete responses in the remaining sarcoma patients (n = 23), although 12 showed 80% to 90% pathologic response. In contrast to the remaining RT-resistant sarcomas, the highly responding specimens contained branching vasculature, partial thrombus formation and inflammation of medium sized arterioles, similar to the vascular changes in MLS.

CONCLUSIONS

Both MLS and sarcomas with MLS-like vasculature are highly radiosensitive. Radiation sensitivity may be explained by changes in medium-sized arterioles, obstructing the specific crow's feet vascularization and inducing hypoxia with secondary tumor cell death.

The intersection of cancer and aging: establishing the need for breast cancer rehabilitation

The increasing success of treatments for common cancers has resulted in growing awareness of the unique health care needs of cancer survivors. Cancer treatments can be toxic and have long-lasting effects on health, potentially accelerating the aging process and producing associated declines in physical function. In this synthesis of the literature, we critically examine the strength of existing evidence that breast cancer diagnosis and treatment are associated with a disproportionate decline in physical function compared with the effects of living without cancer for the same number of years. There is some observational epidemiologic evidence that women treated for breast cancer report greater declines in physical function than their peers. Discerning the factors associated with such declines and their clinical significance remains to be addressed. Physiologic, psychological, and behavioral changes associated with both aging and cancer treatment are reviewed. Parallels are proposed between existing preventive and rehabilitative programs and possibilities for similar interventions aimed at preventing, reversing, or halting declines in physical function in cancer survivors. Finally, a program of research is proposed to evaluate whether there is some subset of breast cancer survivors for whom prevention or rehabilitation of functional status declines is needed, as well as development of targeted, mechanistically driven interventions.

Cardiotoxic Effects of Tangential Breast Irradiation in Early Breast Cancer Patients: The Role of Irradiated Heart Volume

PURPOSE

To assess the risk of cardiovascular disease (CVD) after postlumpectomy irradiation restricted to tangential fields.

METHODS AND MATERIALS

We assessed the incidence of CVD in 1601 patients with T1-2N0 breast cancer (BC) treated with breast tangentials in five different hospitals between 1980 and 1993. Patients treated with radiation fields other than breast tangentials and those treated with adjuvant chemotherapy were excluded. For patients with left-sided BC, maximum heart distance (MHD) was measured on the simulator films as a proxy for irradiated heart volume. Risk of CVD by laterality and MHD categories was evaluated by Cox proportional hazards regression analysis.

RESULTS

Follow-up was complete for 94% of the patients, and median follow-up was 16 years. The incidence of CVD overall was 14.1%, of ischemic heart disease 7.3%, and for other types of heart disease 9.2%, with a median time to event of 10 to 11 years. The incidence of CVD was 11.6% in patients with right-sided BC, compared with 16.0% in left-sided cases. The hazard ratio associated with left-sided vs. right-sided BC was 1.38 (95% confidence interval [CI], 1.05-1.81) for CVD overall, 1.35 (95% CI, 0.93-1.98) for ischemic heart disease , and 1.53 (95% CI, 1.09-2.15) for other heart disease, adjusted for age, diabetes, and history of CVD. The risk of CVD did not significantly increase with increasing MHD.

CONCLUSIONS

Patients irradiated for left-sided BC with tangential fields have a higher incidence of CVD compared with those with right-sided cancer. However, the risk does not seem to increase with larger irradiated heart volumes.

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.