Cardiac dose sparing and avoidance techniques in breast cancer radiotherapy

Rapid Selection of Patients Suitable for Deep Inspiration Breath-Hold Using an Automatic Delineating System and RapidPlan Model in Patients With Left Breast Cancer Undergoing Adjuvant Radiation Therapy With IMRT

PURPOSE

This study aimed to determine whether radiation therapy plans created using an automatic delineating system and a RapidPlan (RP) module could rapidly and accurately predict heart doses and benefit from deep inspiratory breath-hold (DIBH) in patients with left breast cancer.

METHODS AND MATERIALS

One hundred thirty-six clinically approved free breathing (FB) plans for patients with left breast cancer were included, defined as manual delineation-manual plan (MD-MP). A total of 104 of 136 plans were selected for RP model training. A total of 32 of 136 patients were automatically delineated by software, after which the RP generated plans, defined as automatic delineation-RapidPlan (AD-RP). In addition, 40 patients who used DIBH were included to analyze differences in heart benefits from DIBH.

RESULTS

Two RP models were established for post-breast-conserving surgery (BCS) and post-modified radical mastectomy. There were no significant differences in most of the dosimetric parameters between the MD-MP and AD-RP. The heart doses of the 2 plans were strongly correlated in patients after BCS (0.80 ≤ r ≤ 0.88, P < .05) and moderately correlated in patients after postmodified radical mastectomy (0.46 ≤ r ≤ 0.58, P <.05). The RP model predicted the mean heart dose (MHD) within ± 59.67 cGy and ± 63.32 cGy for patients who underwent the 2 surgeries described above. The heart benefits from DIBH were significantly greater in patients with FB-MHD ≥ 4 Gy than in those with FB-MHD < 4 Gy.

CONCLUSIONS

The combined automatic delineation RP model allows for the rapid and accurate prediction of heart dose under FB in patients with left breast cancer. FB-MHD ≥ 4 Gy can be used as a dose threshold to select patients suitable for DIBH.

An IMRT planning technique for treating whole breast or chest wall with regional lymph nodes on Halcyon and Ethos

PURPOSE/OBJECTIVE

Field size limitations on Halcyon and Ethos treatment machines largely preclude use of the conventional monoisocentric three-field technique for breast/chest wall and regional lymph nodes. We present an alternative, IMRT-based planning approach that facilitates treatment on Halcyon and Ethos while preserving plan quality.

MATERIALS/METHODS

Eight breast and regional node cases (four left-sided, four right-sided) were planned for an Ethos machine using a 15-17 field IMRT technique. Institutional plan quality metrics for CTV and PTV coverage and OAR sparing were assessed. Five plans (four right-sided, one left-sided) were also planned using a hybrid 3D multisocenter technique. CTV coverage and OAR sparing were compared to the IMRT plans. Eclipse scripting tools were developed to aid in beam placement and plan evaluation through a set of dosimetric scorecards, and both are shared publicly.

RESULTS

On average, the IMRT plans achieved breast CTV and PTV coverage at 50 Gy of 97.9% and 95.7%, respectively. Supraclavicular CTV and PTV coverages at 45 Gy were 100% and 95.5%. Axillary lymph node CTV and PTV coverages at 45 Gy were 100% and 97.1%, and IMN CTV coverage at 45 Gy was 99.2%. Mean ipsilateral lung V20 Gy was 19.3%, and average mean heart dose was 1.6 Gy for right-sided cases and 3.0 Gy for left-sided. In comparison to the hybrid 3D plans, IMRT plans achieved higher breast and supraclavicular CTV coverage (99.9% vs. 98.6% and 99.9% vs. 93.4%), higher IMN coverage (99.6% vs. 78.2%), and lower ipsilateral lung V20 Gy (19.6% vs. 28.2%).

CONCLUSION

Institutional plan quality benchmarks were achieved for all eight cases using the IMRT-based planning approach. The IMRT-based planning approach offered superior conformity and OAR sparing than a competing hybrid 3D approach.

Intra-fractional dose rate effect in continuous and interrupted irradiation of the MCF-7 cell line: Possible radiobiological implications for breath-hold techniques in breast radiotherapy?

PURPOSE

To investigate the effects of different dose rates (DRs) in continuous and interrupted irradiation on in-vitro survival of the MCF-7 cell line, towards finding possible radiobiological effects of breath-hold techniques in breast radiotherapy (RT), in which intra-fractional beam interruptions and delivery prolongation can occur.

MATERIALS AND METHODS

MCF-7 cells were irradiated continuously or with regular interruptions using 6 MV x-rays at different accelerator DRs (50-400 cGy/min) to deliver a 2 Gy dose. The interrupted irradiation was delivered in a 10 s on, 10 s off manner. Then, cell survival and viability were studied using colony and MTT assays, respectively.

RESULTS

Survival and viability with continuous and interrupted irradiation were similar ( P > 0.5). A significant increase in survival at 50, 100, and 400 cGy/min compared to 200 and 300 cGy/min was observed, also a significant decreasing and then increasing trend from 50 to 200 cGy/min and 200 to 400 cGy/min, respectively ( P < 0.04). Relative to 200 cGy/min, the survival fractions at 50, 100, 300, and 400 cGy/min were 1.24, 1.23, 1.05, and 1.20 times greater, respectively. Cell viability did not show significant differences between the DRs, despite following the same trend as cell survival.

CONCLUSION

Our results suggest that for continuous irradiation of in-vitro MCF-7 cells, with increasing DR within the 50-400 cGy/min range, sensitivity increases and then decreases (inverse effect), also that up to doubling of treatment time in breath-hold techniques does not affect in-vitro radiobiological efficacy with 200-400 cGy/min accelerator DRs. Further confirmatory studies are required.

Competing risk analysis of cardiovascular disease risk in breast cancer patients receiving a radiation boost

BACKGROUND

Thoracic radiotherapy may damage the myocardium and arteries, increasing cardiovascular disease (CVD) risk. Women with a high local breast cancer (BC) recurrence risk may receive an additional radiation boost to the tumor bed.

OBJECTIVE

We aimed to evaluate the CVD risk and specifically ischemic heart disease (IHD) in BC patients treated with a radiation boost, and investigated whether this was modified by age.

METHODS

We identified 5260 BC patients receiving radiotherapy between 2005 and 2016 without a history of CVD. Boost data were derived from hospital records and the national cancer registry. Follow-up data on CVD events were obtained from Statistics Netherlands until December 31, 2018. The relation between CVD and boost was evaluated with competing risk survival analysis.

RESULTS

1917 (36.4%) received a boost. Mean follow-up was 80.3 months (SD37.1) and the mean age 57.8 years (SD10.7). Interaction between boost and age was observed for IHD: a boost was significantly associated with IHD incidence in patients younger than 40 years but not in patients over 40 years. The subdistribution hazard ratio (sHR) was calculated for ages from 25 to 75 years, showing a sHR range from 5.1 (95%CI 1.2-22.6) for 25-year old patients to sHR 0.5 (95%CI 0.2-1.02) for 75-year old patients.

CONCLUSION

In patients younger than 40, a radiation boost is significantly associated with an increased risk of CVD. In absolute terms, the increased risk was low. In older patients, there was no association between boost and CVD risk, which is likely a reflection of appropriate patient selection.

Outcomes with and without postmastectomy radiotherapy for pT3N0-1M0 breast cancer: An institutional experience

AIM

The objective of this study is to comprehensively evaluate the therapeutic efficacy of postmastectomy radiotherapy (PMRT) in treating patients with pT3N0-1M0 breast cancer within the context of modern therapeutic strategies.

METHODS

Clinical data from patients with pT3N0-1M0 breast cancer who underwent mastectomy from January 2005 to December 2018 at our institution were retrospectively analyzed.

RESULTS

The study involved a total of 222 participants, with 112 individuals undergoing PMRT and 110 individuals not receiving it. The median follow-up duration was 77 months (range: 6-171 months). The entire cohort demonstrated 5-year disease-free survival (DFS) and overall survival (OS) rates of 85.1% and 91.0%, respectively, along with a locoregional recurrence (LRR) rate as low as 7.2%. The PMRT group showed significantly better 5-year DFS (90.2% vs. 80.0%, p = 0.02) and OS (95.5% vs. 86.4%, p = 0.012) rates, as well as a lower LRR rate (4.5% vs. 10.0%, p = 0.122), compared to the group without PMRT. Cox regression analysis confirmed the independent prognostic significance of PMRT for both DFS (p = 0.040) and OS (p = 0.047). Following propensity score matching (PSM), the analysis included 100 matched patients, revealing an improved prognosis for those who received PMRT (DFS: p = 0.067; OS: p = 0.043).

CONCLUSIONS

Our study reveals favorable prognoses for pT3N0-1M0 breast cancer patients treated within contemporary therapeutic approaches. The pivotal role of PMRT in this context is evident. However, due to the retrospective design of our study and the relatively limited sample size, further investigation is imperative to validate and enhance these initial findings.

Impact of breath hold on regional nodal irradiation and heart volume in field in left breast cancer adjuvant irradiation

PURPOSE

Compared to the free-breathing technique, adjuvant left breast irradiation after breast-conserving surgery or mastectomy using the breath-hold method significantly reduces the heart mean dose, Left anterior descending artery, and ipsilateral lung doses. Movement with deep inspiration may also reduce heart volume in the field and regional node doses.

MATERIALS AND METHODS

Pre-radiotherapy planning CT was performed in the free-breathing, and breath-hold techniques using RPM, demographic information, clinicopathological data, heart volume in the field, heart mean dose, LAD mean dose, and regional nodal doses were calculated in both free breathing and DIBH. Fifty patients with left breast cancer receiving left breast adjuvant radiation were enrolled.

RESULTS

There was no significant difference in axillary LN coverage between the two techniques, except for SCL maximum dose, Axilla I node maximum dose, and Axilla II minimum dose in favor of the breath hold technique. The mean age was 47.54 years, 78% had GII IDC, 66% had positive LVSI results, and 74% of patients had T2. The breath hold strategy resulted in considerably decreased mean heart dose (p = 0.000), LAD dose (p = 0.000), ipsilateral lung mean dose (p = 0.012), and heart volume if the field (p = 0.013). The mean cardiac dosage and the dose of the LAD were significantly correlated (p = 0.000, R = 0.673). Heart volume in the field and heart mean dosage was not significantly correlated (p = 0.285, r = - 0.108).

CONCLUSION

When compared to free breathing scans, DIBH procedures result in considerably reduced dosage to the OAR and no appreciable changes in dose exposure to regional lymph node stations in patients with left-sided breast cancer.

Cardiorespiratory dose comparison among six radiotherapy regimens for patients with left-sided breast cancer

There is uncertainty regarding the benefits and drawbacks of various radiation protocols for the treatment of left-sided breast cancer. To address this issue, we conducted a Bayesian network analysis. First, we searched several electronic databases for eligible literature. Next, we pooled the data from twelve studies concerning three-dimensional conformal radiation therapy (3D-CRT), intensity modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT), combined with either deep inspiratory breath-holding (DIBH) or free-breathing (FB) modalities. The integrated cardiac and pulmonary dosimetric indexes for all included treatments were compared using Bayesian networks. A direct meta-analysis indicated that for the two methods of 3D-CRT and IMRT, DIBH technology was more effective than FB in reducing the radiation dose to the heart and lungs. Additionally, according to the network results, DIBH was superior to FB in all six treatment options, regardless of whether the plan was 3D-CRT, IMRT, or VMAT. Besides, the combined data indicated that the FB-3D-CRT regimen had the weakest dosimetric advantage of all the treatments. Excluding FB-3D-CRT, each of the other five treatments had its own specific benefits. This is the first Bayesian study of several radiotherapy regimens for breast cancer patients on the left side, and the findings can be used to select appropriate radiotherapy programs for breast cancer patients.

Particle radiotherapy for breast cancer

Breast cancer is the most common malignant tumor in female patients. Along with surgery, radiotherapy is one of the most commonly prescribed treatments for breast cancer. Over the past few decades, breast cancer radiotherapy technology has significantly improved. Nevertheless, related posttherapy complications should not be overlooked. Common complications include dose-related coronary toxicity, radiation pneumonia, and the risk of second primary cancer of the contralateral breast. Particle radiotherapy with protons or carbon ions is widely attracting interest as a potential competitor to conventional photon radiotherapy because of its superior physical and biological characteristics. This article summarizes the results of clinical research on proton and carbon-ion radiotherapy for treating breast cancer.

Dosimetric Evaluation of Cardiac Structures on Left Breast Cancer Radiotherapy: Impact of Movement, Dose Calculation Algorithm and Treatment Technique

BACKGROUND

Breast cancer is the most frequently diagnosed and leading cause of cancer-related deaths among females. The treatment of breast cancer with radiotherapy, albeit effective, has been shown to be toxic to the heart, resulting in an elevated risk of cardiovascular disease and associated fatalities.

METHODS

In this study, we evaluated the impact of respiratory movement, treatment plans and dose calculation algorithm on the dose delivered to the heart and its substructures during left breast radiotherapy over a cohort of 10 patients. We did this through three image sets, four different treatment plans and the employment of three algorithms on the same treatment plan. The dose parameters were then employed to estimate the impact on the 9-year excess cumulative risk for acute cardiac events by applying the model proposed by Darby.

RESULTS

The left ventricle was the structure most irradiated. Due to the lack of four-dimensional computed tomography (4DCT), we used a set of images called phase-average CT that correspond to the average of the images from the respiratory cycle (exhale, exhale 50%, inhale, inhale 50%). When considering these images, nearly 10% of the heart received more than 5 Gy and doses were on average 27% higher when compared to free breathing images. Deep inspiration breath-hold plans reduced cardiac dose for nine out of 10 patients and reduced mean heart dose in about 50% when compared to reference plans. We also found that the implementation of deep inspiration breath-hold would reduce the relative lifetime risk of ischemic heart disease to 10%, in comparison to 21% from the reference plan.

CONCLUSION

Our findings illustrate the importance of a more accurate determination of the dose and its consideration in cardiologists' consultation, a factor often overlooked during clinical examination. They also motivate the evaluation of the dose to the heart substructures to derive new heart dose constraints, and a more mindful and individualized clinical practice depending on the treatment employed.

Evaluation of Cardiac Substructures Exposure of DIBH-3DCRT, FB-HT, and FB-3DCRT in Hypofractionated Radiotherapy for Left-Sided Breast Cancer after Breast-Conserving Surgery: An In Silico Planning Study

Left-sided breast cancer radiotherapy can lead to late cardiovascular complications, including ischemic events. To mitigate these risks, cardiac-sparing techniques such as deep-inspiration breath-hold (DIBH) and intensity-modulated radiotherapy (IMRT) have been developed. However, recent studies have shown that mean heart dose is not a sufficient dosimetric parameter for assessing cardiac exposure. In this study, we aimed to compare the radiation exposure to cardiac substructures for ten patients who underwent hypofractionated radiotherapy using DIBH three-dimensional conformal radiation therapy (3DCRT), free-breathing (FB)-3DCRT, and FB helical tomotherapy (HT). Dosimetric parameters of cardiac substructures were analyzed, and the results were statistically compared using the Wilcoxon signed-rank test. This study found a significant reduction in the dose to the heart, left anterior descending coronary artery, and ventricles with DIBH-3DCRT and FB-HT compared to FB-3DCRT. While DIBH-3DCRT was very effective in sparing the heart, in some cases, it provided little or no cardiac sparing. FB-HT can be an interesting treatment modality to reduce the dose to major coronary vessels and ventricles and may be of interest for patients with cardiovascular risks who do not benefit from or cannot perform DIBH. These findings highlight the importance of cardiac-sparing techniques for precise delivery of radiation therapy.

External-Beam-Accelerated Partial-Breast Irradiation Reduces Organ-at-Risk Doses Compared to Whole-Breast Irradiation after Breast-Conserving Surgery

In order to evaluate organ-at-risk (OAR) doses in external-beam-accelerated partial-breast irradiation (APBI) compared to standard whole-breast irradiation (WBI) after breast-conserving surgery. Between 2011 and 2021, 170 patients with early breast cancer received APBI within a prospective institutional single-arm trial. The prescribed dose to the planning treatment volume was 38 Gy in 10 fractions on 10 consecutive working days. OAR doses for the contralateral breast, the ipsilateral, contralateral, and whole lung, the whole heart, left ventricle (LV), and the left anterior descending coronary artery (LAD), and for the spinal cord and the skin were assessed and compared to a control group with real-world data from 116 patients who underwent WBI. The trial was registered at the German Clinical Trials Registry, DRKS-ID: DRKS00004417. Compared to WBI, APBI led to reduced OAR doses for the contralateral breast (0.4 ± 0.6 vs. 0.8 ± 0.9 Gy, p = 0.000), the ipsilateral (4.3 ± 1.4 vs. 9.2 ± 2.5 Gy, p = 0.000) and whole mean lung dose (2.5 ± 0.8 vs. 4.9 ± 1.5 Gy, p = 0.000), the mean heart dose (1.6 ± 1.6 vs. 1.7 ± 1.4 Gy, p = 0.007), the LV V23 (0.1 ± 0.4 vs. 1.4 ± 2.6%, p < 0.001), the mean LAD dose (2.5 ± 3.4 vs. 4.8 ± 5.5 Gy, p < 0.001), the maximum spinal cord dose (1.5 ± 1.1 vs. 4.5 ± 5.7 Gy, p = 0.016), and the maximum skin dose (39.6 ± 1.8 vs. 49.1 ± 5.8 Gy, p = 0.000). APBI should be recommended to suitable patients to minimize the risk of secondary tumor induction and the incidence of consecutive major cardiac events.

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.

Case report: Early acute myocarditis after radiation therapy for breast cancer: A case presentation and review of literature

Breast cancer is the most commonly diagnosed cancer in women worldwide, and with the increased survival of patients by novel treatments, the frequency of complications of cancer treatments rises. Radiotherapy, especially on the chest wall, can damage different cardiac structures. Radiotherapy-induced cardiomyopathy mainly occurs over 10 years after breast cancer treatment; however, there is a gap in the literature on acute myocarditis following radiotherapy. Here, we present a 54-year-old woman who developed acute myocarditis shortly after 25 sessions of radiotherapy with 50 Gy of radiation, successfully diagnosed with the use of speckle tracking echocardiography (STE) and cardiac magnetic resonance (CMR), and responded to the medical treatment with relative clinical improvement until the final follow-up. This case suggests the necessity of detailed examination of patients after radiotherapy, not only for chronic occurrence of cardiomyopathy but also for acute myocarditis. Although STE and CMR resulted in accurate diagnosis, in this case, further studies are required to determine the diagnostic accuracy of these two imaging methods compared with other imaging modalities in such patients and investigate the best diagnostic tool and therapeutic approach for these patients.

Special Techniques of Adjuvant Breast Carcinoma Radiotherapy

Modern radiotherapy techniques are designed to permit reduced irradiation of healthy tissue, resulting in a diminished risk of adverse effects and shortened recovery times. Several randomized studies have demonstrated the benefits of increased dosage to the tumor bed area in combination with whole breast irradiation (WBI). Conventional WBI treatment following breast-conserving procedures, which required 5-7 weeks of daily treatments, has been reduced to 3-4 weeks when using hyperfractionated regimens. The dosage administration improves local control, albeit with poorer cosmesis. The method of accelerated partial breast irradiation (APBI) shortens the treatment period whilst reducing the irradiated volume. APBI can be delivered using intraoperative radiation, brachytherapy, or external beam radiotherapy. Currently available data support the use of external beam partial breast irradiation in selected patients. Modern radiotherapy techniques make it possible to achieve favorable cosmesis in most patients undergoing immediate breast reconstruction surgery, and studies confirm that current methods of external beam radiation allow an acceptable coverage of target volumes both in the reconstructed breast and in the regional lymphatic nodes.

Dosimetric benefits of 3D-printed modulated electron bolus following lumpectomy and whole-breast radiotherapy for left breast cancer

Radiotherapy with electrons is commonly applied to the tumor bed after whole-breast radiotherapy following breast conservation surgery for breast cancer patients. However, the radiation dose to adjacent organs-at-risk (OARs) and conformity of planning target volume (PTV) cannot be optimized. In this study, we examine the feasibility of using modulated electron bolus (MEB) to improve PTV conformity and reduce the dose to these OARs. Twenty-seven patients with left breast cancer were retrospectively selected in this study. For each patient, a tangential photon plan in RayStation treatment planning system with prescription of 26 Gy in 5 fractions was created as base plan. Two electron plans, one without bolus and one with MEB using Adaptiiv software based on the PTV were created. Various dosimetric parameters of OARs including left lung, heart, left anterior descending artery (LAD) and ribs and the conformity indices of PTV of these 2 electron plans together with the base plans were compared. Statistically significant decreases in the dosimetric parameters (V_5Gy, V_10Gy, V_20Gy, and mean dose) of the ipsilateral left lung and the heart were observed with MEB. The median maximum dose to the LAD and the ribs decreased by 6.2% and 4.5% respectively. The median conformity index was improved by 14.3% with median increases of monitor units by 1.7%. Our results show that MEB is feasible resulting in reduction of doses to the predefined OARs and an improved conformity of PTV. By using 3D printing, MEB might be considered as an alternative to conventional electron boost.

Automated coronary artery calcium scoring in patients with breast cancer to assess the risk of heart disease following adjuvant radiation therapy

Aim

Validation of coronary artery calcium (CAC) scores as prognostic factors of acute coronary events (ACE) development in breast cancer patients are demanded. We investigated prognostic impact of CAC on ACE development with cardiac exposure to radiation.

Methods

We evaluated breast cancer patients with (n = 511) or without (n = 600) adjuvant radiotherapy (RT) between 2005 and 2013. CAC Agatston scores were analyzed using a deep-learning-based algorithm. Individual mean heart dose (MHD) was calculated, and no RT was categorized as 0 Gy. The primary endpoint was the development of ACE following breast surgery.

Results

In the RT and no-RT cohorts, 11.2% and 3.7% exhibited CAC >0, respectively. Over a 9.3-year follow-up period, the 10-year ACE rate was 0.7%. In the multivariate analysis, the CAC score was a significant risk factor for ACE (CAC >0 vs CAC = 0, 10-year 6.2% vs 0.2%, P < 0.001). In the subgroup with CAC >0, the 10-year ACE rates were 0%, 3.7%, and 13.7% for patients receiving mean heart doses of 0 Gy, 0–3 Gy, and >3 Gy, respectively (P = 0.133). Although CAC score was not predictive for non-ACE heart disease risk (P > 0.05), the 10-year non-ACE heart disease rates were 1.7%, 5.7%, and 7.1% for patients with CAC = 0 receiving MHD of 0 Gy, 0–3 Gy, and >3 Gy, respectively (P < 0.001).

Conclusions

The CAC score was a significant predictor of ACE in patients with breast cancer. Although further studies are required, CAC score screening on simulation CT in patients undergoing breast RT can help identify those with high risk for ACE on a per-patient basis.

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CAC score was successfully validated as a strong predictive factor for ACEs.

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MHD was identified as a significant factor in development of ACE and NAHD.

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Best efforts should be made to keep the dose to cardiac structures as low as possible.

A Critical Overview of Predictors of Heart Sparing by Deep-Inspiration-Breath-Hold Irradiation in Left-Sided Breast Cancer Patients

Simple Summary

Adjuvant radiotherapy could damage the heart in left-sided breast cancer patients. The deep-inspiration-breath-hold technique may limit the heart exposure to radiation. As non-beneficiaries exist, there is some need to do an upfront cost-effective selection. Some easy-to-use anatomical predictors may help insiders in the treatment decision. The awareness of such findings may improve the efficiency of practitioners’ workflows.

Abstract

Radiotherapy represents an essential part of the therapeutic algorithm for breast cancer patients after conservative surgery. The treatment of left-sided tumors has been associated with a non-negligible risk of developing late-onset cardiovascular disease. The cardiac risk perception has especially increased over the last years due to the prolongation of patients’ survival owing to the advent of new drugs and an ever earlier cancer detection through screening programs. Improvements in radiation delivery techniques could reduce the treatment-related heart toxicity. The deep-inspiration-breath-hold (DIBH) irradiation is one of the most advanced treatment approaches, which requires specific technical equipment and uses inspiration to displace the heart from the tangential radiation fields. However, not all patients benefit from its use. Moreover, DIBH irradiation needs patient compliance and accurate training. Therefore, such a technique may be unjustifiably cumbersome and time-consuming as well as unnecessarily expensive from a mere healthcare cost point of view. Hence the need to early select only the true beneficiaries while tailoring more effective heart-sparing techniques for the others and streamlining the workflow, especially in high-volume radiation oncology departments. In this literature overview, we collected some possible predictors of cardiac dose sparing in DIBH irradiation for left breast treatment in an effort to provide an easy-to-consult summary of simple instruments to insiders for identifying patients actually benefitting from this technique. We critically reviewed the reliability and weaknesses of each retrieved finding, aiming to inspire new insights and discussions on this much-debated topic.

Comparison of Deep Inspiration Breath Hold Versus Free Breathing in Radiotherapy for Left Sided Breast Cancer

Objectives

Modern breast cancer techniques, such as the deep inspiration breath-hold (DIBH) technique has been applied for left-sided breast cancer. Whether the DIBH regimen is the optimal solution for left-sided breast cancer remains unclear. This meta-analysis aims to elucidate the differences of DIBH and free-breathing (FB) for patients receiving radiotherapy for left-sided breast cancer and provide a practical reference for clinical practice.

Methods

Relevant research available on PubMed, Embase, Cochrane Library, and the Web of Science published before November 30, 2021 was independently and systematically examined by two investigators. Data were extracted from eligible studies for assessing their qualities and calculating the standardized mean difference (SMD) and 95% confidence intervals (CIs) using Review Manager software 5.4 (RevMan 5.4).

Results

Forty-one studies with a total of 3599 left-sided breast cancer patients were included in the meta-analysis. Compared with FB, DIBH reduced heart dose (Dmean, Dmax, V30, V10, V5), left anterior descending branch (LAD) dose (Dmean, Dmax), ipsilateral lung dose (Dmean, V20, V10, V5), and heart volume significantly. Lung volume increased greatly, and a statistically significant difference. For contralateral breast mean dose, DIBH has no obvious advantage over FB. The funnel plot suggested this study has no significant publication bias.

Conclusions

Although DIBH has no obvious advantage over FB in contralateral breast mean dose, it can significantly reduce heart dose, LAD dose, ipsilateral lung dose, and heart volume. Conversely, it can remarkably increase the ipsilateral lung volume. This study suggests that soon DIBH could be more widely utilized in clinical practice because of its excellent dosimetric performance.

Comparison of treatment plans between static jaw and jaw tracking techniques in postmastectomy intensity-modulated radiation therapy

This study reports a dosimetric comparison between treatment plans using static jaw and jaw tracking techniques in intensity-modulated radiation therapy (IMRT) for postmastectomy radiation therapy (PMRT). Seventeen patients treated for left-sided breast cancer with implant-based reconstruction were subjected to IMRT plans. Another group of 22 patients treated for left-sided breast cancer without reconstruction was also subjected to IMRT plans. The plans were generated using the Eclipse treatment planning system with static jaw and jaw tracking techniques. The dose-volume histograms and dosimetric indices, such as mean dose (D_mean), V_{20 Gy}, V_{10 Gy}, and V_{5 Gy} (volumes receiving 20, 10, and 5 Gy at the least, respectively), and generalized equivalent uniform dose for organs at risk (OARs) were analyzed. A significant difference in the value of the dosimetric indices between the static jaw and jaw tracking plans was observed. For jaw tracking plans, the D_mean of the heart for the patients with implant-based reconstruction reduced from 11.6 ± 1.1 Gy to 10.0 ± 1.8 Gy, whereas the V_{5 Gy} reduced from 92.0 ± 4.5% to 85.1 ± 8.4%. The D_mean of the heart for patients without reconstruction reduced from 11.0 ± 2.3 Gy to 9.8 ± 2.6 Gy, whereas the V_{5 Gy} reduced from 81.4 ± 13.6% to 66.7 ± 17.4%. The dosimetric indices of OARs in the jaw tracking plans were significantly lower than those of the OARs in the static jaw plans. The jaw tracking technique was more effective for patients without reconstruction than for those with implant-based reconstruction.

Hadrontherapy techniques for breast cancer

Radiotherapy plays a key role in breast cancer treatment, and recent technical advances have been made to improve the therapeutic window by limiting the risk of radiation-induced toxicity or by increasing tumor control. Hadrontherapy is a form a radiotherapy relying on particle beams; compared with photon beams, particle beams have specific physical, radiobiological and immunological properties, which can be valuable in diverse clinical situations. To date, available hadrontherapy techniques for breast cancer irradiation include proton therapy, carbon ion radiation therapy, fast neutron therapy and boron neutron capture therapy. This review analyzes the current rationale and level of evidence for each hadrontherapy technique for breast cancer.

A clinical trial to compare a 3D-printed bolus with a conventional bolus with the aim of reducing cardiopulmonary exposure in postmastectomy patients with volumetric modulated arc therapy

BACKGROUND

We compared the dosimetry, application, and acute toxicity of a 3D-printed and a conventional bolus for postmastectomy radiotherapy (PMRT) with volumetric modulated arc therapy (VMAT). Materials and Methods Eligible patients (n = 75) with PMRT breast cancer were randomly selected to receive VMAT with a conventional bolus or a 3D-printed bolus. The primary endpoint was a 10% decrease in the mean heart dose to left-sided breast cancer patients. The secondary endpoint was a 5% decrease in the mean ipsilateral lung dose to all patients. A comparative analysis was carried out of the dosimetry, normal tissue complication probability (NTCP), acute skin toxicity, and radiation pneumonitis.

RESULTS

Compared to a conventional bolus, the mean heart dose in left-sided breast cancer was reduced by an average of 0.8 Gy (5.5 ± 1.3 Gy vs. 4.7 ± 0.8 Gy, p = 0.035) and the mean dose to the ipsilateral lung was also reduced by an average of 0.8 Gy (12.4 ± 1.0 Gy vs. 11.6 ± 0.8 Gy, p < 0.001). The values for V_50Gy of the PTV of the chest wall for the 3D-printed and conventional boluses were 95.4 ± 0.6% and 94.8 ± 0.8% (p = 0.026) and the values for the CI of the entire PTV were 0.83 ± 0.02 and 0.80 ± 0.03 (p < 0.001), respectively. The NTCP for the 3D-printed bolus was also reduced to an average of 0.14% (0.32 ± 0.19% vs. 0.18 ± 0.11%, p = 0.017) for the heart and 0.45% (3.70 ± 0.67% vs. 3.25 ± 0.18%, p < 0.001) for the ipsilateral lung. Grade 2 and Grade 1 radiation pneumonitis were 0.0% versus 7.5% and 14.3% versus 20.0%, respectively (p = 0.184).

CONCLUSIONS

The 3D-printed bolus may reduce cardiopulmonary exposure in postmastectomy patients with volumetric modulated arc therapy.

The impact of modern radiotherapy on long-term cardiac sequelae in breast cancer survivor: a focus on deep inspiration breath-hold (DIBH) technique

INTRODUCTION

One of the most feared side effects of radiotherapy (RT) in the setting of breast cancer (BC) patients is cardiac toxicity. This side effect can jeopardize the quality of life (QoL) of long-term survivors. The impact of modern techniques of RT such as deep inspiration breath hold (DIBH) have dramatically changed this setting. We report and discuss the results of the literature overview of this paper.

MATERIALS AND METHODS

Literature references were obtained with a PubMed query, hand searching, and clinicaltrials.gov.

RESULTS

We reported and discussed the toxicity of RT and the improvements due to the modern techniques in the setting of BC patients.

CONCLUSIONS

BC patients often have a long life expectancy, thus the RT should aim at limiting toxicities and at the same time maintaining the same high cure rates. Further studies are needed to evaluate the risk-benefit ratio to identify patients at higher risk and to tailor the treatment choices.

Adjuvant radiotherapy did not increase the risk of coronary heart disease in patients with non-metastatic breast cancer

OBJECTIVE

Adjuvant radiotherapy (RT) in patients with breast cancer can adversely cause the heart to receive some radiation doses, which may lead to cardiovascular diseases. The results of previous research regarding this issue are not consistent. Therefore, we conducted a nationwide population-based study in Taiwan to evaluate whether adjuvant RT for breast cancer patients increased the risk of developing coronary heart disease (CHD).

METHODS

This retrospective cohort study examined data from the National Health Insurance Research Database, Registry for Catastrophic Illness Patients, and Taiwan Cancer Registry Database. We identified 83,733 patients with breast cancer between 1 January 2000 and 31 December 2017. Individuals without breast cancer from the general population were frequency-matched by age and index year with individuals with breast cancer. Participants were followed until the occurrence of a CHD event, the end of follow-up, or patient record removal due to death or withdrawal from the NHI. A Cox proportional hazards regression analysis was conducted to compare the risk of CHD in breast cancer patients with that in patients in the comparison cohort.

RESULTS

Compared to breast cancer patients without RT, those who underwent RT had a similar risk of subsequently developing CHD (adjusted hazard ratio, 0.94; 95% confidence interval, 0.87-1.02). Similar results were observed in a subgroup of patients with left-sided breast cancer. However, among patients who received adjuvant RT, those with left-sided breast cancer had a significantly higher risk of CHD than did those with right-sided breast cancer (adjusted hazard ratio, 1.17; 95% confidence interval, 1.04-1.30). Patients who received RT in 2010 or later had a significantly lower risk of CHD compared with those who received RT before 2010 (adjusted hazard ratio, 0.64; 95% confidence interval, 0.45-0.91). Higher prescribed doses of RT to the left-sided breast did not correspond to a higher risk of CHD.

CONCLUSION

This large, nationwide cohort study suggests that adjuvant RT in patients with breast cancer did not increase the risk of CHD.

Advances in Breast Cancer Radiotherapy: Implications for Current and Future Practice

Radiation therapy (RT) is an essential component in the management of breast cancer. Following breast-conserving surgery (BCS), adjuvant RT is the standard of care for most patients. Traditionally, RT was delivered with standard whole breast irradiation (WBI) over 5-7 weeks following BCS. However, WBI regimens have evolved; hypofractionated WBI now represents the standard approach, reducing the duration of treatment to 3-4 weeks. Over the past year, five-fraction WBI regimens have also emerged as standard of care for some patients based on data from the FAST and FAST-Forward trials. An alternative to WBI that is also available for patients with early-stage breast cancer following BCS is partial breast irradiation, which can reduce the duration of treatment and the volume of breast tissue irradiated. Outcomes from multiple randomized trials with over a 10-year follow-up have demonstrated the safety and efficacy of partial breast irradiation approaches. Single-fraction intraoperative RT has also been evaluated in two prospective trials although the outcomes available, as well as current guidelines, do not support its utilization outside of prospective studies. For patients requiring RT to the regional lymph nodes, data have demonstrated the safety of hypofractionated approaches for those undergoing BCS or mastectomy without reconstruction. Future directions for early-stage breast cancer radiotherapy include the study of even shorter regimens and studies evaluating the omission of RT versus omission of endocrine therapy for favorable-risk patients. Furthermore, studies are also underway evaluating shorter courses of radiation in patients undergoing breast reconstruction and the use of tumor genomics to identify appropriate patients for omission of radiation with limited nodal involvement.

Coronary Artery Disease in Young Women After Radiation Therapy for Breast Cancer: The WECARE Study

Background

Radiation therapy (RT) for breast cancer increases risk of coronary artery disease (CAD). Women treated for left- vs right-sided breast cancer receive greater heart radiation exposure, which may further increase this risk. The risk of radiation-associated CAD specifically among younger breast cancer survivors is not well defined.

Objectives

The purpose of this study was to report CAD risk among participants in the Women's Environmental Cancer and Radiation Epidemiology Study.

Methods

A total of 1,583 women who were <55 years of age when diagnosed with breast cancer between 1985 and 2008 completed a cardiovascular health questionnaire. Risk of radiation-associated CAD was evaluated by comparing women treated with left-sided RT with women treated with right-sided RT using multivariable Cox proportional hazards models. Effect modification by treatment and cardiovascular risk factors was examined.

Results

In total, 517 women who did not receive RT and 94 women who had a pre-existing cardiovascular disease diagnosis were excluded, leaving 972 women eligible for analysis. Their median follow-up time was 14 years (range 1-29 years). The 27.5-year cumulative incidences of CAD for women receiving left- vs right-sided RT were 10.5% and 5.8%, respectively (P = 0.010). The corresponding HR of CAD for left- vs right-sided RT in the multivariable Cox model was 2.5 (95% CI: 1.3-4.7). There was no statistically significant effect modification by any factor evaluated.

Conclusions

Young women treated with RT for left-sided breast cancer had over twice the risk of CAD compared with women treated with RT for right-sided breast cancer. Laterality of RT is independently associated with an increased risk of CAD and should be considered in survivorship care of younger breast cancer patients.

Dosimetry and outcomes in patients receiving radiotherapy for synchronous bilateral breast cancers

BACKGROUND

Synchronous bilateral breast cancer (SBBC) is rare and there is little evidence describing organs at risk (OAR) and limits to the heart and lungs caused by radiotherapy (RT). Quantifying mean heart dose (MHD) and mean lung dose (MLD) from RT in this patient cohort may lead to better understanding of doses to OAR and resultant effects on clinical outcomes. The primary objective was to assess median MHD and MLD in SBBC, while secondary aims included analyses of 1) factors associated with MHD and MLD, 2) V5 and V20 values and 3) factors associated with clinical outcomes.

METHODS

Patients planned for adjuvant bilateral whole breast/chest wall (WB) RT from a single institution treated in 2011-2018 were included. Median MHD and MLD (Gy) were stratified by hypofractionated (42.56 Gy/16 fractions, HFRT) and conventional fractionation (50 Gy/ 25 fractions, CFRT) and summarized separately based on the following treatments: 1) locoregional RT, WB tangential RT either 2) no boost 3) sequential boost or 4) simultaneous integrated boost. MHD, MLD, lung V5 and V20 values, and demographics were collected. Linear regression analyses identified factors associated with MHD and MLD and factors associated with clinical outcomes.

RESULTS

A total of 88 patients were included. The median MHD for HFRT and CFRT was 1.99 Gy and 2.94 Gy, respectively. The median MLD for HFRT and CFRT was 6.00 Gy and 10.08 Gy, respectively. MHD and MLD were significantly associated with the occurrence of a cardiac or pulmonary event post-radiation. Patients who had a mastectomy or tumoral muscle involvement were more likely to develop a local recurrence, metastasis or new primary while patients who had a lumpectomy or tumor with a positive estrogen receptor status were less likely to experience these events.

CONCLUSIONS

Further investigation should be conducted to identify SBBC RT techniques that mitigate dose to OARs to improve clinical outcomes in bilateral breast patients.

Health care costs for adolescents and young adults with cancer: a Wisconsin community-based hospital study between 2005 and 2020

INTRODUCTION

Adolescents and young adults (AYA) with cancer are at risk of high cumulative healthcare system costs potentially associated with poor health and financial outcomes. Although this has been studied at academic centers, little data on AYA costs at community-based practices exist. The goals of this study were to understand direct health care costs for AYA patients, identify factors for high costs, and assess how total health care costs may relate to survival.

METHODS

AYA patients (15-39 years) treated at a community hospital in Wisconsin (USA) between 2005 and 2020 were identified. Patient demographics, cancer characteristics, therapies, support services, and all direct health care charges (including up to 1 year prior to diagnosis to capture any diagnostic workup) were collected. Logistic and Cox proportional hazard regression models identified factors associated with high costs and survival, respectively.

RESULTS

The 388 AYA patients had a median follow-up of 9 years (97% survival). Most were 30-39 years (62%), female (61%), white (95%), diagnosed early-stage (85%), and underwent surgery (83%). Complete health care costs were available for 233 patients (60%). Median total costs per patient were $123 K (range, $73-$215 K). On adjusted analysis, higher direct health care costs (> $125 K) were associated with greater odds of hospital admissions (odds ratio [OR] = 1.7, 95% CI = 1.35-2.27), chemotherapy (OR = 4.1, 95% CI = 1.44-12.70), and breast cancer diagnosis (OR = 3.8, 95% CI = 1.07-14.70). Living farther from the hospital (OR = 0.1, 95% CI = 0.02-0.50), later year of diagnosis (OR = 0.7, 95% CI = 0.55-0.77), and uninsured/unknown insurance status (OR = 0.1, 95% CI = 0.01-0.57) were associated with decreased odds of having higher health care costs. On adjusted analysis, death was associated with greater odds of higher direct health care costs per $125 K (hazards ratio [HR] = 7.9, 95% CI = 2.22-27.80) and radiation (HR = 31.8, 95% CI = 3.15-321) but lower odds of hormone therapy (HR = 0.1, 95% CI = 0.01-0.72) and later year of diagnosis (HR = 0.3, 95% CI = 0.12-0.60).

CONCLUSION

High direct health care costs among AYA patients are associated with hospital admissions, chemotherapy, breast cancer diagnosis, hospital proximity, and earlier year of diagnosis. Death was associated with high direct health care costs, earlier years of diagnosis, and radiation therapy. Total health care costs in community-based hospitals should be considered in the context of AYA patients with cancer.

Radiation Oncologists' Approach to Internal Mammary Lymph Node Radiotherapy in Breast Cancer: The Turkish Society for Radiation Oncology Breast Cancer Study Group (TROD 06-005 Survey Study)

Background

This study aimed to examine the practice patterns of radiation oncologists in Turkey regarding radiotherapy to the regional lymph nodes, including internal mammary lymph nodes (IMNs), and identify the factors influencing their clinical decisions in breast cancer patients.

Methods

A nationwide, 19-point questionnaire was sent to the physician members of the Turkish Society for Radiation Oncology (TROD).

Results

In total, 165 radiation oncologists completed the survey, corresponding to a 27% response rate. Regional radiotherapy was used in 64.2% of the patients with 1-3 axillary lymphatic involvement and unfavorable prognostic factors. In contrast, 61.2% of the respondents indicated that IMN should be included in the target volume for regional radiotherapy when the patient had one positive node after axillary lymph node dissection (ALND) in the inner quadrant and central region tumors. However, 71.5% of the respondents chose to include the IMN in the non-inner quadrant and non-central region tumors for patients with four or more positive nodes after ALND. The decision to offer internal mammary lymph node radiotherapy (IMNRT) varied widely and significantly among respondents, years in practice, and the rates of dedicating their clinical time to patients with breast cancer.

Conclusion

The results of this survey revealed significant national variation in attitudes regarding the treatment of IMN. Thus, this study may also help document the impact of future studies on clinical practice.

Assessment of visual feedback system for reproducibility of voluntary deep inspiration breath hold in left-sided breast radiotherapy

INTRODUCTION

Deep inspiration breath-hold (DIBH) for left-sided breast cancer radiotherapy reduces the dose exposure of the heart and left anterior descending coronary artery. DIBH requires the patient to maintain an adequate breath-hold position during their daily radiotherapy fraction. This study aimed to assess the reproducibility of the breath-hold position by implementing DIBH with visual feedback (VF) system.

METHODS

Forty-three patients who underwent left-sided radiotherapy with DIBH were reviewed. Data from 35 patients who underwent DIBH with VF (VF-DIBH) were compared with data from 8 patients who underwent DIBH with audio coaching (AC-DIBH). Reproducibility during radiotherapy was evaluated using the portal images obtained. Images were acquired daily during the tangential field treatment with DIBH. The distances between the field edge and chest wall at the central beam axis were manually measured on the portal image and digital reconstruction radiograph (DRR). The displacements of the chest wall during radiotherapy were assessed by subtracting the measurement made on the portal image from the DRR measurement. The overall average distances for the VF-DIBH and AC-DIBH cohorts were compared to assess reproducibility. The statistical analysis was performed using Mann-Whitney U tests (p < 0.05).

RESULTS

The mean chest wall displacement (±2 SD) was 0.59 ± 3.64 mm for VF-DIBH and 2.09 ± 4.96 mm for AC-DIBH, respectively. This value differed significantly between the VF-DIBH and AC-DIBH cohorts (p < 0.001).

CONCLUSION

In DIBH radiotherapy, the implementation of VF was confirmed to improve breath-hold position reproducibility, and the utility of VF for DIBH was demonstrated.

Cardiac Magnetic Resonance Imaging and Blood Biomarkers for Evaluation of Radiation-Induced Cardiotoxicity in Patients With Breast Cancer: Results of a Phase 2 Clinical Trial

PURPOSE

Radiation therapy (RT) can increase the risk of cardiac events in patients with breast cancer (BC), but biomarkers predicting risk for developing RT-induced cardiac disease are currently lacking. We report results from a prospective clinical trial evaluating early magnetic resonance imaging (MRI) and serum biomarker changes as predictors of cardiac injury and risk of subsequent cardiac events after RT for left-sided disease.

METHODS

Women with node-negative and node-positive (N-/+) left-sided BC were enrolled on 2 institutional review board (IRB)-approved protocols at 2 institutions. MRI was conducted pretreatment (within 1 week of starting radiation), at the end of treatment (last day of treatment ±1 week), and 3 months after the last day of treatment (±2 weeks) to quantify left and right ventricular volumes and function, myocardial fibrosis, and edema. Perfusion changes during regadenoson stress perfusion were also assessed on a subset of patients (n = 28). Serum was collected at the same time points. Whole heart and cardiac substructures were contoured using CT and MRI. Models were constructed using baseline cardiac and clinical risk factors. Associations between MRI-measured changes and dose were evaluated.

RESULTS

Among 51 women enrolled, mean heart dose ranged from 0.80 to 4.7 Gy and mean left ventricular (LV) dose from 1.1 to 8.2 Gy, with mean heart dose 2.0 Gy. T1 time, a marker of fibrosis, and right ventricular (RV) ejection fraction (EF) significantly changed with treatment; these were not dose dependent. T2 (marker of edema) and LV EF did not significantly change. No risk factors were associated with baseline global perfusion. Prior receipt of doxorubicin was marginally associated with decreased myocardial perfusion after RT (P = .059), and mean MHD was not associated with perfusion changes. A significant correlation between baseline IL-6 and mean heart dose (MHD) at the end of RT (ρ 0.44, P = .007) and a strong trend between troponin I and MHD at 3 months post-treatment (ρ 0.33, P = .07) were observed. No other significant correlations were identified.

CONCLUSIONS

In this prospective study of women with left-sided breast cancer treated with contemporary treatment planning, cardiac radiation doses were very low relative to historical doses reported by Darby et al. Although we observed significant changes in T1 and RV EF shortly after RT, these changes were not correlated with whole heart or substructure doses. Serum biomarker analysis of cardiac injury demonstrates an interesting trend between markers and MHD that warrants further investigation.

Future Perspectives of Proton Therapy in Minimizing the Toxicity of Breast Cancer Radiotherapy

The toxicity of radiotherapy is a key issue when analyzing the eligibility criteria for patients with breast cancer. In order to obtain better results, proton therapy is proposed because of the more favorable distribution of the dose in the patient’s body compared with photon radiotherapy. Scientific groups have conducted extensive research into the improved efficacy and lower toxicity of proton therapy for breast cancer. Unfortunately, there is no complete insight into the potential reasons and prospects for avoiding undesirable results. Cardiotoxicity is considered challenging; however, researchers have not presented any realistic prospects for preventing them. We compared the clinical evidence collected over the last 20 years, providing the rationale for the consideration of proton therapy as an effective solution to reduce cardiotoxicity. We analyzed the parameters of the dose distribution (mean dose, Dmax, V5, and V20) in organs at risk, such as the heart, blood vessels, and lungs, using the following two irradiation techniques: whole breast irradiation and accelerated partial breast irradiation. Moreover, we presented the possible causes of side effects, taking into account biological and technical issues. Finally, we collected potential improvements in higher quality predictions of toxic cardiac effects, like biomarkers, and model-based approaches to give the full background of this complex issue.

Dosimetric Comparison of Radiation Techniques for Comprehensive Regional Nodal Radiation Therapy for Left-Sided Breast Cancer: A Treatment Planning Study

Purpose

How modern cardiac sparing techniques and beam delivery systems using advanced x-ray and proton beam therapy (PBT) can reduce incidental radiation exposure doses to cardiac and pulmonary organs individually or in any combination is poorly investigated.

Methods

Among 15 patients with left-sided breast cancer, partial wide tangential 3D-conformal radiotherapy (3DCRT) delivered in conventional fractionation (CF) or hypofractionated (HF) schedules; PBT delivered in a CF schedule; and volumetric modulated arc therapy (VMAT) delivered in an HF schedule, each under continuous positive airway pressure (CPAP) and free-breathing (FB) conditions, were examined. Target volume coverage and doses to organs-at-risk (OARs) were calculated for each technique. Outcomes were compared with one-way analysis of variance and the Bonferroni test, with p-values <0.05 considered significant.

Results

Target volume coverage was within acceptable levels in all interventions, except for the internal mammary lymph node D95 (99% in PBT, 90% in VMAT-CPAP, 84% in VMAT-FB, and 74% in 3DCRT). The mean heart dose (MHD) was the lowest in PBT (<1 Gy) and VMAT-CPAP (2.2 Gy) and the highest in 3DCRT with CF/FB (7.8 Gy), respectively. The mean lung dose (MLD) was the highest in 3DCRT-CF-FB (20 Gy) and the lowest in both VMAT-HF-CPAP and PBT (approximately 5-6 Gy). VMAT-HF-CPAP and PBT delivered a comparable maximum dose to the left ascending artery (7.2 and 6.13 Gy, respectively).

Conclusions

Both proton and VMAT in combination with CPAP can minimize the radiation exposure to heart and lung with optimal target coverage in regional RT for left-sided breast cancer. The clinical relevance of these differences is yet to be elucidated. Continued efforts are needed to minimize radiation exposures during RT treatment to maximize its therapeutic index.

Were We Able to Reduce Cardiac Doses in Breast Cancer Radiotherapy Over Time?

Objective

In this study, we aimed to review the heart and left coronary artery doses over the years in patients who received breast cancer radiotherapy (RT).

Materials and Methods

A total of 436 breast cancer patients of 2 RT centers treated between the years 2010 and 2018 were included. The mean heart doses (HeartDmean-HDM) and left coronary artery mean doses (LDM) were analyzed using nonparametric tests. The conventional RT (CRT) was 50 Gy/2 Gy in 5 weeks, and the hypofractionated RT (HRT) was 40.05 Gy/2.67 Gy in 3 weeks. Boost was applied as 10-16 Gy/2 Gy for CRT and 10 Gy/2.5 Gy for HRT. An equivalent conventional total dose of 2 Gy/fraction (EQD2) was taken into account for HRT.

Results

HDM was 107±104 cGy, and LDM was 288±209 cGy for the entire group. HDM was significantly lower in patients with breast-conserving surgery (99±94 cGy) than that in those with mastectomy (128±124 cGy) (p<0.001). Field-in-field intensity-modulated RT technique significantly reduced the doses compared to volumetric applications (104±95 cGy vs 141±38 cGy; p = 0.002). HDM was significantly increased with lymphatic RT (132±58 cGy vs 112±115 cGy; p<0.001). The addition of internal mammary volumes significantly increased HDM (p<0.001). No significant effect of boost was observed (p = 0.96). For both CRT and HRT regimens, HDM values were significantly lower after the year 2014 (right side p<0.001, left side p = 0.01). In the left side CRT, HDM was 1.74 Gy before 2014 and 1.3 Gy after 2014 and 1.0 and 1.19 Gy, respectively, for the right side.

Conclusion

All efforts to reduce the cardiac doses will likely reduce long-term side effects.

[Concomitant radiotherapy and trastuzumab: Rational and clinical implications]

The HER2 receptor (Human Epidermal Growth Receptor 2) is a transmembrane receptor with tyrosine kinase activity that is over-expressed in 25-30 % of breast carcinomas. Its activation is associated with an exaggeration of cell proliferation with an increase in repair capacity resulting in increased radioresistance. On cardiac tissues, HER2 receptor activation plays a cardio-protective role. Trastuzumab, the first anti-HER2 drug used to treat patients with breast cancer overexpressing HER2 receptor , inhibits the cascade of reactions resulting in the proliferation of tumor cells, thus restoring cellular radiosensitivity. However, the combination of Trastuzumab with radiation therapy also removes HER2 receptor cardio-protective role on myocardial cells which increases the risk of cardiotoxicity. Thus, the concomitant association of these two modalities has long been a subject of controversy. Recent advances in radiation therapy technology and early detection of cardiac injury may limit the cardiotoxicity of this combination. Through this review, we developed the biological basis and the benefit-risk of concomitant combination of radiotherapy and Trastuzumab in adjuvant treatment of breast cancers overexpressing HER2 and we discuss the modalities of its optimization.

The Association Between Cardiac Mortality and Adjuvant Radiation Therapy Among Older Patients With Stage I Estrogen Positive Breast Cancer: A Surveillance, Epidemiology, and End Results (SEER)-Based Study on Cardiac Mortality and Radiation Therapy

PURPOSE

We evaluated the risk of cardiac mortality in older patients who receive adjuvant radiation therapy (RT) for stage I breast cancer to determine whether this risk persists in the modern era.

METHODS AND MATERIALS

Using the 2000 to 2015 Surveillance, Epidemiology, and End Results program data, we performed a population-based cohort study to evaluate the association between adjuvant breast RT, tumor laterality, and cardiac-specific survival (CSS) among patients 60 and older with stage I estrogen receptor positive breast cancer who received breast-conserving surgery and RT.

RESULTS

At a median follow-up of 6 years (range, 0-15.9 years), patients receiving RT for left-sided breast cancer demonstrated no difference in 5- and 10-year CSS compared with those with right-sided breast cancer (5 year 98.3% vs 98.2%, 10 year 94.3% vs 93.9%; log-rank P = .56). Cox proportional hazards regression analysis confirmed the lack of association of tumor laterality on adjusted 5-year CSS (hazard ratio [HR] = 0.96; 95% confidence interval [CI] = 0.87-1.06), breast-cancer specific survival (HR = 0.96; 95% CI = 0.85-1.09), and overall survival (HR = 0.98; 95% CI = 0.94-1.03). There was also no association of inner versus outer quadrant location on adjusted 5-year CSS for right-sided (HR = 1.06; 95% CI = 0.89-1.12) and left-sided breast cancer (HR = 0.95; 95% CI = 0.79-1.15).

CONCLUSIONS

With modern radiation therapy techniques, older patients who received left-sided RT for stage I estrogen-receptor positive breast cancer do not demonstrate an increased risk of cardiac mortality compared with patients with right-sided breast cancer. RT can be offered to older patients without concern for inducing cardiac-related death.

Retrospective Study on Left-Sided Breast Radiotherapy: Dosimetric Results and Correlation with Physical Factors for Free Breathing and Breath Hold Irradiation Techniques

Objectives: In breast radiotherapy, the proximity of the target to sensitive structures together with the uncertainty introduced by respiratory movement, make this treatment one of the most studied to increase its effectiveness. Dosimetric and physical variables play an important role and the study of their correlation and impact on treatment is fundamental. This retrospective study aims to highlight the dosimetric differences of 2 different clinical data sets of patients receiving left-sided breast irradiation in free breathing (FB) or breath hold (BH). Methods: A total of 155 left breast carcinoma patients receiving whole-breast irradiation in FB (73 patients) and BH (82 patients) were enrolled in this study. The dosimetric parameters of the target, heart, left and right lung and right breast were evaluated and compared, and possible correlations were studied in both groups. Results: No significant difference (P > .05) was found in the target dosimetry; a clear advantage in BH for both high and low doses received by the heart, with reductions of the dosimetric parameters between 27.1% and 100% (P < .003); for the left lung reductions decreased with increasing dose (-22.4% and -13.4% for doses of 5 and 20 Gy, respectively, P < .003). Conclusion: Significant correlations for BH treatments were registered between the volumes of the target and left lung, and the dosimetric parameters of the heart and left lung. BH treatment brings significant dosimetric advantages to organs at risk for a wide range of patients with different anatomy, target volumes and lung capacity, with additional benefits for small-sized breasts and important lung capacity.

Proton versus Photon Breath-Hold Radiation for Left-Sided Breast Cancer after Breast-Conserving Surgery: A Dosimetric Comparison

PURPOSE

Radiation to breast, chest wall, and/or regional nodes is an integral component of breast cancer management in many situations. Irradiating left-sided breast and/or regional nodes may be technically challenging because of cardiac tolerance and subsequent risk of long-term cardiac complications. Deep inspiratory breath-hold (DIBH) technique physically separates cardiac structures away from radiation target volume, thus reducing cardiac dose with either photon (Ph) or proton beam therapy (PBT). The utility of combining PBT with DIBH is less well understood.

METHODS AND MATERIALS

We compared photon-DIBH (Ph-DIBH) versus proton DIBH (Pr-DIBH) for different planning parameters, including target coverage and organ at risk (OAR) sparing. Necessary ethical permission was obtained from the institutional review board. Ten previous patients with irradiated, intact, left-sided breast and Ph-DIBH were replanned with PBT for dosimetric comparison. Clinically relevant normal OARs were contoured, and Ph plans were generated with parallel, opposed tangent beams and direct fields for supraclavicular and/or axillae whenever required. For proton planning, all targets were delineated individually and best possible coverage of planning target volume was achieved. Dose-volume histogram was analyzed to determine the difference in doses received by different OARs. Minimum and maximum dose (Dmin and Dmax ) as well as dose received by a specific volume of OAR were compared. Each patient's initial plan (Ph-DIBH) was used as a control for comparing newly devised PBT plan (Pr-DIBH). Matched, paired t tests were applied to determine any significant differences between the 2 plans.

RESULTS

Both the plans were adequate in target coverage. Dose to cardiac structure subunits and ipsilateral lung were significantly reduced with the proton breath-hold technique. Significant dose reduction with Pr-DIBH was observed in comparison to Ph-DIBH for mean dose (D mean) to the heart (0.23 Gy versus 1.19 Gy; P < .001); D mean to the left ventricle (0.25 Gy versus 1.7 Gy; P < .001); D mean, D max, and the half-maximal dose to the left anterior descending artery (1.15 Gy versus 5.54 Gy; P < .003; 7.7 Gy versus 22.15 Gy; P < .007; 1.61 Gy versus 4.42 Gy, P < .049); D max of the left circumflex coronary artery (0.13 Gy versus 1.35 Gy; P < .001) and D mean, the volume to the ipsilateral lung receiving 20 Gy and 5 Gy (2.28 Gy versus 8.04 Gy; P < .001; 2.36 Gy versus 15.54 Gy, P < .001; 13.9 Gy versus 30.28 Gy; P = .002). However, skin dose and contralateral breast dose were not significantly improved with proton.

CONCLUSION

This comparative dosimetric study showed significant benefit of Pr-DIBH technique compared with Ph-DIBH in terms of cardiopulmonary sparing and may be the area of future clinical research.

Cardiac doses of accelerated partial breast irradiation with perioperative multicatheter interstitial brachytherapy

PURPOSE

To quantify mean heart dose (MHD) and doses to the left anterior descending artery (LAD) and left ventricle (LV) in a retrospective series of patients who underwent perioperative accelerated partial breast irradiation with multicatheter interstitial brachytherapy (MIB-APBI).

METHODS

Sixty-eight patients with low-risk left breast cancer were treated with MIB-APBI at our institution between 2012 and 2017. Interstitial tubes were inserted during the tumorectomy and sentinel node biopsy and APBI was started 6 days later. The prescribed dose was 34 Gy in 10 fractions (twice a day) to the clinical target volume (CTV). The heart, LAD, and LV were contoured and the distance between each structure and the CTV was measured. The MHD, mean and maximum LAD doses (LAD mean/max), and mean LV doses (LV mean) were calculated and corrected to biologically equivalent doses in 2‑Gy fractionation (EQD2). We also evaluated the impact of the distance between the cardiac structures and the CTV and of the volume receiving the prescribed dose (V100) and high-dose volume (V150) on heart dosimetry.

RESULTS

Mean EQD2 for MHD, LAD mean/max, and mean LV were 0.9 ± 0.4 Gy (range 0.3-2.2), 1.6 ± 1.1 Gy (range, 0.4-5.6), 2.6 ± 1.9 Gy (range, 0.7-9.2), and 1.3 ± 0.6 Gy (range, 0.5-3.4), respectively. MHD, LAD mean/max, and LV mean significantly correlated with the distance between the CTV and these structures, but all doses were below the recommended limits (German Society of Radiation Oncology; DEGRO). The MHD and LV mean were significantly dependent on V100.

CONCLUSION

Perioperative MIB-APBI resulted in low cardiac doses in our study. This finding provides further support for the value of this technique in well-selected patients with early-stage left breast cancer.

Heart substructural dosimetric parameters and risk of cardiac events after definitive chemoradiotherapy for stage III non-small cell lung cancer

INTRODUCTION

We evaluated the incidence of cardiac events after chemoradiotherapy in patients with stage III non-small cell lung cancer (NSCLC) based on baseline cardiovascular risk and the heart substructures' radiation dose.

METHODS

From 2008 to 2018, the cardiac events of 258 patients with stage III NSCLC who received definitive chemoradiotherapy were reviewed. The 10-year cardiovascular risk was calculated using the Atherosclerotic Cardiovascular Disease (ASCVD) scoring system. Dose-volume histograms were estimated for each cardiac chamber. A multivariate competing-risk regression analysis was conducted to assess each cardiac event's subhazard function (SHR).

RESULTS

The median follow-up was 27.5 months overall and 38.9 months for survivors. Among the 179 deaths, none was definitely related to cardiac conditions. Altogether, 32 cardiovascular events affected 27 patients (10.5%) after chemoradiotherapy. Ten were major cardiac adverse events, including heart failure (N = 6) and acute coronary syndrome (ACS, N = 4). Most cardiovascular events were related to well-known risk factors. However, the volume percentage of the left ventricle (LV) receiving 60 Gy (LV V60) > 0 was significantly associated with ACS (SHR = 9.49, 95% CI = 1.28-70.53, P = 0.028). In patients with high cardiovascular risk (ASCVD score > 7.5%), LV V60 > 0% remained a negative ACS prognostic factor (P = 0.003). Meanwhile, in patients with low cardiovascular risk, the LV radiation dose was not associated with ACS events (P = 0.242).

CONCLUSIONS

A high LV radiation dose could increase ACS events in patients with stage III NSCLC and high cardiovascular risk. Pre-treatment cardiac risk evaluation and individualized surveillance may help prevent cardiac events after chemoradiotherapy.

Feasibility study: spot-scanning proton arc therapy (SPArc) for left-sided whole breast radiotherapy

BACKGROUND

This study investigated the feasibility and potential clinical benefit of utilizing a new proton treatment technique: Spot-scanning proton arc (SPArc) therapy for left-sided whole breast radiotherapy (WBRT) to further reduce radiation dose to healthy tissue and mitigate the probability of normal tissue complications compared to conventional intensity modulated proton therapy (IMPT).

METHODS

Eight patients diagnosed with left-sided breast cancer and treated with breast-preserving surgery followed by whole breast irradiation without regional nodal irradiation were included in this retrospective planning. Two proton treatment plans were generated for each patient: vertical intensity-modulated proton therapy used for clinical treatment (vIMPT, gantry angle 10°-30°) and SPArc for comparison purpose. Both SPArc and vIMPT plans were optimized using the robust optimization of ± 3.5% range and 5 mm setup uncertainties. Root-mean-square deviation dose (RMSD) volume histograms were used for plan robustness evaluation. All dosimetric results were evaluated based on dose-volume histograms (DVH), and the interplay effect was evaluated based on the accumulation of single-fraction 4D dynamic dose on CT50. The treatment beam delivery time was simulated based on a gantry rotation with energy-layer-switching-time (ELST) from 0.2 to 5 s.

RESULTS

The average D1 to the heart and LAD were reduced to 53.63 cGy and 82.25 cGy compared with vIMPT 110.38 cGy (p = 0.001) and 170.38 cGy (p = 0.001), respectively. The average V5Gy and V20Gy of ipsilateral lung was reduced to 16.77% and 3.07% compared to vIMPT 25.56% (p = 0.001) and 4.68% (p = 0.003). Skin3mm mean and maximum dose were reduced to 3999.38 cGy and 4395.63 cGy compared to vIMPT 4104.25 cGy (p = 0.039) and 4411.63 cGy (p = 0.043), respectively. A significant relative risk reduction (RNTCP = NTCP_SPArc/NTCP_vIMPT) for organs at risk (OARs) was obtained with SPArc ranging from 0.61 to 0.86 depending on the clinical endpoint. The RMSD volume histogram (RVH) analysis shows SPArc provided better plan robustness in OARs sparing, including the heart, LAD, ipsilateral lung, and skin. The average estimated treatment beam delivery times were comparable to vIMPT plans when the ELST is about 0.5 s.

CONCLUSION

SPArc technique can further reduce dose delivered to OARs and the probability of normal tissue complications in patients treated for left-sided WBRT.

Two-Level Factorial Pre-TomoBreast Pilot Study of Tomotherapy and Conventional Radiotherapy in Breast Cancer: Post Hoc Utility of a Mean Absolute Dose Deviation Penalty Score

Background:

A 2-level factorial pilot study was conducted in 2007 just before starting a randomized clinical trial comparing tomotherapy and conventional radiotherapy (CR) to reduce cardiac and pulmonary adverse effects in breast cancer, considering tumor laterality (left/right), target volume (with/without nodal irradiation), surgery (tumorectomy/mastectomy), and patient position (prone/supine). The study was revisited using a penalty score based on the recently developed mean absolute dose deviation (MADD).

Methods:

Eight patients with a unique combination of laterality, nodal coverage, and surgery underwent dual tomotherapy and CR treatment planning in both prone and supine positions, providing 32 distinct combinations. The penalty score was applied using the weighted sum of the MADDs. The Lenth method for unreplicated 2-level factorial design was used in the analysis.

Results:

The Lenth analysis identified nodal irradiation as the active main effect penalizing the dosimetry by 1.14 Gy (P = 0.001). Other significant effects were left laterality (0.94 Gy), mastectomy (0.61 Gy), and interactions between left mastectomy (0.89 Gy) and prone mastectomy (0.71 Gy), with P-values between 0.005 and 0.05. Tomotherapy provided a small reduction in penalty (reduction of 0.54 Gy) through interaction with nodal irradiation (P = 0.080). Some effects approached significance with P-values > 0.05 and ≤ 0.10 for interactions of prone × mastectomy × left (0.60 Gy), nodal irradiation × mastectomy (0.59 Gy), and prone × left (0.55 Gy) and the main effect prone (0.52 Gy).

Conclusions:

The historical dosimetric analysis previously revealed the feasibility of tomotherapy, but a conclusion could not be made. The MADD-based score is promising, and a new analysis highlights the impact of factors and hierarchy of priorities that need to be addressed if major gains are to be attained.

Exclusive endocrine therapy or partial breast irradiation for women aged ≥70 years with luminal A-like early stage breast cancer (NCT04134598 - EUROPA): Proof of concept of a randomized controlled trial comparing health related quality of life by patient reported outcome measures

BACKGROUND

Postoperative radiation therapy after breast conserving surgery in the older adult population is a matter of debate; although radiation therapy was shown to benefit these patients concerning local disease control, the absolute benefit was small and potentially negligible. Partial breast irradiation has been introduced as an alternative treatment approach for low-risk patients. Older adult patients with early breast cancer constitute a unique population with regards to prognosis and potential comorbidities, thus minimizing treatment to maintain health-related quality of life (HRQoL) without compromising survival is extremely important. Estimates of the patient's risk of benefit and/or harm with treatment should be performed together with an assessment of baseline comorbidities, life expectancy, and care preferences. Published data suggest that radiation therapy or endocrine therapy alone resulted in excellent disease control in older women with early breast cancer, and that the combination of both treatments has less incremental benefit than expected. Conversely, the toxicity profile of endocrine therapy is well known, often significantly impacting long term HRQoL of these potentially frail patients.

METHODS

Patients older than 70  years receiving breast conserving surgery with T1N0, Luminal A-like tumors will be randomized to receive partial breast irradiation-alone or endocrine therapy-alone. The main objectives are to determine patient reported outcome measures in terms of HRQoL, as assessed by the EORTC QLQ-C30 using the global health status of patients, and to demonstrate a non-inferior local control rate between arms. Secondary endpoints are represented by individual scales from QLQ-C30 and module QLQ-BR45 scores; ELD14 questionnaire; geriatric COre DatasEt assessment; distant control rate, adverse events rates, breast cancer specific, and overall survival.

DISCUSSION

The EUROPA trial is a new randomized trial focused on older adults (≥70  years) affected by good prognosis primary breast cancer. Our assumption is that postoperative radiation therapy-alone avoids the long-term toxicity of endocrine therapy and favorably impacts on HRQoL in this population. In the current report we present the trial's background and methods, focusing on perspectives in the field of precision medicine.

TRIAL REGISTRATION

The trial is registered with ClinicalTrial.gov Identifier NCT04134598 / EUROPA trial.

Stereotactic Radiotherapy for the Management of Refractory Ventricular Tachycardia: Promise and Future Directions

Ventricular tachycardia (VT) caused by myocardial scaring bears a significant risk of mortality and morbidity. Antiarrhythmic drug therapy (AAD) and catheter ablation remain the cornerstone of VT management, but both treatments have limited efficacy and potential adverse effects. Stereotactic body radiotherapy (SBRT) is routinely used in oncology to treat non-invasively solid tumors with high precision and efficacy. Recently, this technology has been evaluated for the treatment of VT. This review presents the basic underlying principles, proof of concept, and main results of trials and case series that used SBRT for the treatment of VT refractory to AAD and catheter ablation.

Dosimetric evaluation of deep inspiration breath hold for left-sided breast cancer: analysis of patient-specific parameters related to heart dose reduction

Deep inspiration breath hold (DIBH) is a common method used worldwide for reducing the radiation dose to the heart. However, few studies have reported on the relationship between dose reduction and patient-specific parameters. The aim of this study was to compare the reductions of heart dose and volume using DIBH with the dose/volume of free breathing (FB) for patients with left-sided breast cancer and to analyse patient-specific dose reduction parameters. A total of 85 Asian patients who underwent whole-breast radiotherapy after breast-conserving surgery were recruited. Treatment plans for FB and DIBH were retrospectively generated by using an automated breast planning tool with a two-field tangential intensity-modulated radiation therapy technique. The prescribed dose was 50 Gy in 25 fractions. The dosimetric parameters (e.g., mean dose and maximum dose) in heart and lung were extracted from the dose-volume histogram. The relationships between dose-volume data and patient-specific parameters, such as age, body mass index (BMI), and inspiratory volume, were analyzed. The mean heart doses for the FB and DIBH plans were 1.56 Gy and 0.75 Gy, respectively, a relative reduction of 47%. There were significant differences in all heart dosimetric parameters (p < 0.001). For patients with a high heart dose in the FB plan, a relative reduction of the mean heart dose correlated with inspiratory volume (r = 0.646). There was correlation between the relative reduction of mean heart dose and BMI (r = -0.248). We recommend considering the possible feasibility of DIBH in low BMI patients because the degree of benefit from DIBH varied with BMI.

Accelerated partial breast irradiation with interstitial multicatheter brachytherapy after breast-conserving surgery for low-risk early breast cancer

Patients with low-risk invasive ductal carcinoma treated with breast-conserving surgery (BCS) were included in a multicatheter brachytherapy APBI protocol. The primary endpoint was ipsilateral breast recurrence. Between December 2008–December 2017, 186 low-risk breast cancer patients were treated with APBI using interstitial multicatheter brachytherapy and followed prospectively. At 5-years of follow-up, cumulative local recurrence (LR) and cause-specific survival was 1.1% (95% CI 0.3–1.9) and 98.3% (95% CI 97.3–99.3%) respectively. No grade 3 adverse effects were observed. Postoperative APBI using multicatheter brachytherapy after BCS in early breast cancer patients have excellent rates of local control and survival, without significant toxicity.

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Low risk early breast cancer patients have low rate of recurrences.

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APBI with interstitial multicatheter brachytherapy in low risk early breast cancer patients have excellent rates of local control and survival.

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Reducing time of treatment.

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Reducing adverse effects.