Significant reductions in heart and lung doses using deep inspiration breath hold with active breathing control and intensity-modulated radiation therapy for patients treated with locoregional breast irradiation

The Potential Role of Intensity-modulated Proton Therapy in the Regional Nodal Irradiation of Breast Cancer: A Treatment Planning Study

AIMS

To investigate the role of intensity-modulated proton therapy (IMPT) for regional nodal irradiation in patients with breast carcinoma in comparison with volumetric-modulated arc therapy (VMAT).

MATERIALS AND METHODS

A cohort of 20 patients (10 in the breast-conserving surgery group and 10 post-mastectomy patients with tissue expander implants) was investigated. Proton plans were also computed using robust optimisation methods. Plan quality was assessed by means of dose-volume histograms and scored with conventional metrics. Estimates of the risk of secondary cancer induction (excess absolute risk, EAR) were carried out, taking into account fractionation, repopulation and repair.

RESULTS

Concerning target coverage, the data proved a substantial equivalence of VMAT and IMPT: for example, coverage for the 50 Gy target, expressed in terms of V_98%, was 47.8 ± 0.4, 47.6 ± 0.4, 47.3 ± 0.8, consistent with the objective of 47.5 Gy, for post-mastectomy patients for the three groups of patients. Also, the conformality of the dose distributions was similar for the two techniques, about 1.1, without statistically significant differences. Organ at risk planning aims were achieved for all structures for both techniques. The mean dose to the ipsilateral lung was 10.8 ± 1.1, 6.2 ± 0.8, 7.2 ± 1.0; for the contralateral lung was 3.2 ± 0.7, 0.3 ± 0.2, 0.4 ± 0.2; for the contralateral breast was: 3.1 ± 0.7, 0.3 ± 0.3 and 0.3 ± 0.3, whereas it was 3.9 ± 0.9, 0.4 ± 0.3 and 0.5 ± 0.5, respectively, for the heart for VMAT, IMPT and robust IMPT plans over the whole group of patients. Robust optimisation affected the near-to-maximum dose values for contralateral lung and breast, the mean dose for the heart and ipsilateral lung, with a deterioration ranging from 20 to 40% of the nominal value of IMPT plans (e.g. from 8.1 ± 6.4 to 11.4 ± 8.8 for the heart compared with 16.2 ± 5.2 for the VMAT plans). The numerical values of EAR per 10 000 patient-years were about one order of magnitude higher for VMAT than for IMPT for contralateral structures: 11.66 ± 2.01, 0.89 ± 0.80, 0.98 ± 0.77 for the contralateral breast and the three groups of plans, respectively; 14.31 ± 2.75, 1.42 ± 0.80, 1.78 ± 0.87 for the contralateral lung; and 34.86 ± 2.64, 18.85 ± 2.15, 20.98 ± 2.35 for the ipsilateral lung.

CONCLUSION

IMPT with or without robust optimisation seems to be a potentially promising approach for the radiation treatment of breast cancer when nodal volumes should be irradiated. This was measured in terms of dosimetric advantage and predicted clinical benefit. In fact, the significant reduction in estimated EAR could add further clinical value to the dosimetric sparing of the organs at risk achievable with IMPT.

External-beam radiation therapy versus surgery in the treatment of hepatocellular carcinoma with inferior vena cava/right atrium tumor thrombi

BACKGROUND

Both surgery and external-beam radiotherapy are effective treatments for hepatocellular carcinoma (HCC) patients with inferior vena cava/right atrium (IVC/RA) tumor thrombi. At present, it is not clear which modality is more suitable. We therefore compared outcomes between surgery and radiotherapy for these patients.

METHODS

We retrospectively reviewed 108 HCC patients with IVC/RA tumor thrombi who were referred for surgery (n = 51) and external-beam radiotherapy (n = 57) at three institutions. Different surgical methods were selected according to the classification of the tumor thrombus. Radiotherapy was designed to focus on primary intrahepatic tumors and tumor thrombi. Predictors of time to progression (TTP) were identified by using univariate and multivariate analyses.

RESULTS

The median TTP was significantly longer in the radiotherapy group than in the surgery group (5.0 months vs 4.2 months; P = 0.010). The multivariate analysis revealed that independent factors predicting shorter TTP were treatment with surgery (HR = 0.577; 95% CI, 0.385-0.865; P = 0.008) and intrahepatic tumor size larger than 10 cm (HR = 0.561; 95% CI, 0.342-0.919; P = 0.022). The median survival times for the radiotherapy and surgery groups were 12.8 and 14.5 months, respectively; the two groups did not have a significant difference in survival (P = 0.466).

CONCLUSIONS

For HCC patients with IVC/RA tumor thrombi, treatment with external-beam radiotherapy and intrahepatic tumor size smaller than 10 cm may predict longer TTP. Compared with complicated surgery, radiotherapy, as a noninvasive treatment modality, may be more likely to be accepted.

Hypofractionated radiotherapy as a salvage treatment for recurrent hepatocellular carcinoma with inferior vena cava/right atrium tumor thrombus: a multi-center analysis

Background

Recurrent hepatocellular carcinoma (HCC) with a tumor thrombus (TT) extending into the inferior vena cava (IVC)/right atrium (RA) is generally regarded as a terminal-stage condition and there is no worldwide consensus on the proper management of this situation. In the present study, we report the efficacy of hypofractionated radiotherapy (HFRT) as a salvage treatment for recurrent HCC with IVC/RA TT.

Methods

We retrospectively reviewed 75 HCC patients with an IVC/RA TT who were referred for HFRT at three institutions between 2008 and 2016. 57 cases had a TT located in the IVC (IVC group), and 18 cases had a TT located in the IVC and RA (IVC + RA group). HFRT was designed to focus on the TT with or without the primary intrahepatic tumors.

Results

In all cases, the TT completely disappeared (CR) in 17 patients (22.7%), 55 patients (73.3%) had a partial response (PR), and 3 patients (4.0%) had a stable disease (SD). There were no cases of progressive disease (PD). The 1-, 2-, and 3-year overall survival rates of the 75 patients were 38.7% (29/75), 13.3% (10/75) and 5.3% (4/75), respectively. The overall median survival time was 10 months. The mean survival times for the IVC group and IVC+ RA group were 13.8 ± 1.1 and 11.6 ± 2.5 months, respectively. There was no significant difference in survival between the two groups (p = 0.205). Log-rank test revealed that factors predicting poor survival were Child-Pugh B liver function classification, AFP ≥ 400 μg/L, intrahepatic multiple tumors, distant metastases, only the TT as the target, a biological effective dose (BED) < 55 Gy and no chance of further radiotherapy.

Conclusions

HFRT appears to be an effective and reasonable treatment option for recurrent HCC patients with IVC/RA TT. The location of the tumor thrombus, either in IVC or in IVC and RA, is not the factor that influences the efficacy of radiotherapy or survival.

Deep inspiration breath-hold for left-sided breast irradiation: Analysis of dose-mass histograms and the impact of lung expansion

Background

The aim of this study was to compare dose-volume histogram (DVH) with dose-mass histogram (DMH) parameters for treatment of left-sided breast cancer in deep inspiration breath-hold (DIBH) and free breathing (FB). Additionally, lung expansion and anatomical factors were analyzed and correlated to dose differences.

Methods

For 31 patients 3D conformal radiation therapy plans were retrospectively calculated on FB and DIBH CTs in the treatment planning system. The calculated doses, structures and CT data were transferred into MATLAB and DVHs and DMHs were calculated. Mean doses (Dmean), volumes and masses receiving certain doses (Vx, Mx) were determined for the left lung and the heart. Additionally, expansion of the left lung was evaluated using deformable image registration. Differences in DVH and DMH dose parameters between FB and DIBH were statistically analyzed and correlated to lung expansion and anatomical factors.

Results

DIBH reduced Dmean (DVH) and relative V20 (V20 [%]) of the left lung in all patients, on average by − 19 ± 9% (mean ± standard deviation) and − 24 ± 10%. Dmean (DMH) and M20 [%] were also significantly reduced (− 12 ± 11%, − 16 ± 13%), however 4 patients had higher DMH values in DIBH than in FB. Linear regression showed good correlations between DVH and DMH parameters, e.g. a dosimetric benefit smaller than 8.4% for Dmean (DVH) in DIBH indicated more irradiated lung mass in DIBH than in FB. The mean expansion of the left lung between FB and DIBH was 1.5 ± 2.4 mm (left), 16.0 ± 4.0 mm (anterior) and 12.2 ± 4.6 mm (caudal). No significant correlations were found between expansions and differences in Dmean for the left lung. The heart dose in DIBH was reduced in all patients by 53% (Dmean) and this dosimetric benefit correlated to lung expansion in anterior.

Conclusions

Treatment of left-sided breast cancer in DIBH reduced dose to the heart and in most cases the lung dose, relative irradiated lung volume and lung mass. A mass related dosimetric benefit in DIBH can be achieved as long as the volume related benefit is about ≥8–9%. The lung expansion (breathing pattern) showed no impact on lung dose, but on heart dose. A stronger chest breathing (anterior expansion) for DIBH seems to be more beneficial than abdominal breathing.

A seven-year experience of using moderate deep inspiration breath-hold for patients with early-stage breast cancer and dosimetric comparison

We present our seven-year experience of using moderate deep inspiration breath-hold (mDIBH) with an active breathing control (ABC) device for patients with early-stage breast cancer and dosimetric comparison to evaluate the benefit of mDIBH on the heart, lung, and liver.We retrospectively reviewed all patients with newly diagnosed breast cancer and having clinical stage Tis, I, or II disease treated between November 2010 and October 2017. Among the 369 patients included in this study, 107 patients were treated with mDIBH and 262 patients were treated with free breathing (FB). Dosimetric analysis was performed to compare dose distribution in the heart, lung, and liver between the two treatment groups. The chi-square test was used to compare the distribution of stage and tumor site between the two groups. The independent samples t-test was used to compare the remaining parameters between the two groups.For all 369 patients, there was a significantly lower ipsilateral lung V5 (relative volume receiving ≧5 Gy), ipsilateral lung V10, ipsilateral lung V20, mean ipsilateral lung dose, whole lung V5, whole lung V10, whole lung V20, mean whole lung dose, heart V10, heart V30, heart V40, and mean heart dose in the mDIBH group. For 184 patients with a left-sided breast tumor, significantly lower ipsilateral lung V5, ipsilateral lung V10, ipsilateral lung V20, mean ipsilateral lung dose, whole lung V10, whole lung V20, mean whole lung dose, heart V10, heart V30, heart V40, and mean heart dose were observed in the mDIBH group. For 185 patients with a right-sided breast tumor, significantly lower ipsilateral lung V5, ipsilateral lung V10, ipsilateral lung V20, mean ipsilateral lung dose, whole lung V5, whole lung V10, whole lung V20, mean whole lung dose, heart V10, heart V30, heart V40, mean heart dose, liver V30, and mean liver dose were observed in the mDIBH group.For early-stage breast cancer patients, mDIBH reduces not only the heart dose but also the lung and liver doses. The routine integration of mDIBH using an ABC device may decrease radiation-induced toxicity in the heart, lung, and liver.

[Left-sided breast cancer locoregional radiation therapy with rotational intensity-modulated irradiation and deep inspiration breath hold: Dosimetric comparison]

PURPOSE

Adjuvant left-sided breast cancer locoregional radiotherapy can be accounted for long-term cardiac toxicity. The deep inspiration breath hold techniques can reduce cardiac doses. Only a few studies have investigated rotational intensity-modulated radiotherapy with deep inspiration breath hold.

MATERIAL AND METHODS

We conducted a dosimetric study comparing rotational intensity-modulated radiotherapy in free breathing with deep inspiration breath hold for irradiation of left breast cancer and locoregional lymph nodes. Doses to organs at risk were compared, as well as doses to coronary arteries, left anterior descending coronary artery region, and aortic valve.

RESULTS

The data from nine patients were included in the study. Treatment plans were comparable for target volumes. The deep inspiration breath hold delivery technique, compared with free breathing, reduced radiation dose to the heart (mean dose 4.8Gy vs. 6.6Gy, p=0.008; dose in 2% of the volume 16.8Gy vs. 23.3Gy, p=0.008; volume receiving 25Gy 0.8% vs. 2,2%, p=0.008; volume receiving 30Gy 0.4% vs. 1.2%, p=0.009), as well as to the right coronary artery (mean dose 6Gy vs. 8.9Gy, p=0.028), to the left anterior descending artery (mean dose 9.6Gy vs. 14.6Gy, p=0.021), to the left anterior descending coronary artery region (dose in 2% of the volume 17.4Gy vs. 24.6Gy, p=0.021), and to the aortic valve (mean dose 4.8Gy vs. 7Gy, p=0.028). Other doses to organs at risk were similar.

CONCLUSION

Rotational intensity-modulated radiotherapy with deep inspiration breath hold is associated with better sparing of the heart, on the right and left anterior descending coronary arteries, and on the aortic valve, compared with free breathing techniques, for adjuvant left breast cancer locoregional irradiation.

Progress in image-guided radiotherapy for the treatment of non-small cell lung cancer

Lung cancer is one of the most common malignant tumors. It has the highest incidence and mortality rate of all cancers worldwide. Late diagnosis of non-small cell lung cancer (NSCLC) is very common in clinical practice, and most patients miss the chance for radical surgery. Thus, radiotherapy plays an indispensable role in the treatment of NSCLC. Radiotherapy technology has evolved from the classic two-dimensional approach to three-dimensional conformal and intensity-modulated radiotherapy. However, how to ensure delivery of an accurate dose to the tumor while minimizing the irradiation of normal tissues remains a huge challenge for radiation oncologists, especially due to the positioning error between fractions and the autonomous movement of organs. In recent years, image-guided radiotherapy (IGRT) has greatly increased the accuracy of tumor irradiation while reducing the irradiation dose delivered to healthy tissues and organs. This paper presents a brief review of the definition of IGRT and the various technologies and applications of IGRT. IGRT can help ensure accurate dosing of the target area and reduce radiation damage to the surrounding normal tissue. IGRT may increase the local control rate of tumors and reduce the incidence of radio-therapeutic complications.

Reproducibility of the lung anatomy under active breathing coordinator control: Dosimetric consequences for scanned proton treatments

PURPOSE

The treatment of moving targets with scanned proton beams is challenging. For motion mitigation, an Active Breathing Coordinator (ABC) can be used to assist breath-holding. The delivery of pencil beam scanning fields often exceeds feasible breath-hold durations, requiring high breath-hold reproducibility. We evaluated the robustness of scanned proton therapy against anatomical uncertainties when treating nonsmall-cell lung cancer (NSCLC) patients during ABC controlled breath-hold.

METHODS

Four subsequent MRIs of five healthy volunteers (3 male, 2 female, age: 25-58, BMI: 19-29) were acquired under ABC controlled breath-hold during two simulated treatment fractions, providing both intrafractional and interfractional information about breath-hold reproducibility. Deformation vector fields between these MRIs were used to deform CTs of five NSCLC patients. Per patient, four or five cases with different tumor locations were modeled, simulating a total of 23 NSCLC patients. Robustly optimized (3 and 5 mm setup uncertainty respectively and 3% density perturbation) intensity-modulated proton plans (IMPT) were created and split into subplans of 20 s duration (assumed breath-hold duration). A fully fractionated treatment was recalculated on the deformed CTs. For each treatment fraction the deformed CTs representing multiple breath-hold geometries were alternated to simulate repeated ABC breath-holding during irradiation. Also a worst-case scenario was simulated by recalculating the complete treatment plan on the deformed CT scan showing the largest deviation with the first deformed CT scan, introducing a systematic error. Both the fractionated breath-hold scenario and worst-case scenario were dosimetrically evaluated.

RESULTS

Looking at the deformation vector fields between the MRIs of the volunteers, up to 8 mm median intra- and interfraction displacements (without outliers) were found for all lung segments. The dosimetric evaluation showed a median difference in D98% between the planned and breath-hold scenarios of -0.1 Gy (range: -4.1 Gy to 2.0 Gy). D98% target coverage was more than 57.0 Gy for 22/23 cases. The D1 cc of the CTV increased for 21/23 simulations, with a median difference of 0.9 Gy (range: -0.3 to 4.6 Gy). For 14/23 simulations the increment was beyond the allowed maximum dose of 63.0 Gy, though remained under 66.0 Gy (110% of the prescribed dose of 60.0 Gy). Organs at risk doses differed little compared to the planned doses (difference in mean doses <0.9 Gy for the heart and lungs, <1.4% difference in V35 [%] and V20 [%] to the esophagus and lung).

CONCLUSIONS

When treating under ABC controlled breath-hold, robustly optimized IMPT plans show limited dosimetric consequences due to anatomical variations between repeated ABC breath-holds for most cases. Thus, the combination of robustly optimized IMPT plans and the delivery under ABC controlled breath-hold presents a safe approach for PBS lung treatments.

Tangent-based volumetric modulated arc therapy for advanced left breast cancer

PURPOSE

To introduce the benefits of tangent-based volumetric modulated arc therapy (TVMAT), an innovative radiotherapy planning technique, compared with traditional volumetric modulated arc therapy (VMAT) for advanced left breast cancer needing nodal irradiation.

MATERIALS AND METHODS

Twenty-three patients with advanced left breast cancer who had received modified radical mastectomy (MRM) and needed adjuvant radiotherapy including nodal irradiation were assessed. Among 23 radiotherapy treatment plans, 17 plans were designed by using TVMAT technique and 6 plans were designed by using traditional VMAT. The main difference of TVMAT from VMAT was that the area of avoidance sector within specific degrees of angle that had no monitor unit (MU) delivery was used in the arc planning, including a total of 5 sectors in 5 partial arcs. The dosimetries of planning target volume (PTV), right breast, bilateral lungs, and heart between TVMAT and VMAT were compared.

RESULTS

The conformity index (CI) and homogeneity index (HI) of PTV between two groups were statistically equivalent (CI: 0.98 ± 0.02 and 0.98 ± 0.03, P = 0.431; HI: 0.12 ± 0.03 and 0.11 ± 0.05, P = 0.177), which indicated that the treatment efficacy of the plans regarding TVMAT was compatible with VMAT. However, all neighboring organs at risk (OAR) showed a great percentage of reduction in mean doses (right breast: 53.1%, right lung: 37.7%, left lung: 8.8%, heart: 21.2%) and low dose parameters (V10: right breast: 72.3%, right lung: 86.1%, left lung: 12.5%, heart: 25.1%; V5: right breast: 56.5%, right lung: 28.3%, left lung: 12.7%, heart: 18.2%) by using TVMAT.

CONCLUSION

TVMAT greatly decreases the radiation doses delivered to the OAR with maintained therapeutic efficacy. It is highly recommended for treating breast cancer, especially for difficult cases with left side disease needing nodal irradiation.

Potential Morbidity Reduction With Proton Radiation Therapy for Breast Cancer

Proton radiotherapy confers significant dosimetric advantages in the treatment of malignancies that arise adjacent to critical radiosensitive structures. To date, these advantages have been most prominent in the treatment of pediatric and central nervous system malignancies, although emerging data support the use of protons among other anatomical sites in which radiotherapy plays an important role. With advances in the overall treatment paradigm for breast cancer, most patients with localized disease now exhibit long-term disease control and, consequently, may manifest the late toxicities of aggressive treatment. As a result, there is increasing emphasis on the mitigation of iatrogenic morbidity, with particular attention to heart and lung exposure in those receiving adjuvant radiotherapy. Indeed, recent landmark analyses have demonstrated an increase in significant cardiac events that is linked directly to low-dose radiation to the heart. Coupled with practice-changing trials that have expanded the indications for comprehensive regional nodal irradiation, there exists significant interest in employing novel technologies to mitigate cardiac dose while improving target volume coverage. Proton radiotherapy enjoys distinct physical advantages over photon-based approaches and, in appropriately selected patients, markedly improves both target coverage and normal tissue sparing. Here, we review the dosimetric evidence that underlies the putative benefits of proton radiotherapy, and further synthesize early clinical evidence that supports the efficacy and feasibility of proton radiation in breast cancer. Landmark, prospective randomized trials are underway and will ultimately define the role for protons in the treatment of this disease.

Dosimetric evaluation and systematic review of radiation therapy techniques for early stage node-negative breast cancer treatment

Radiation therapy (RT) is essential in treating women with early stage breast cancer. Early stage node-negative breast cancer (ESNNBC) offers a good prognosis; hence, late effects of breast RT becomes increasingly important. Recent literature suggests a potential for an increase in cardiac and pulmonary events after RT. However, these studies have not taken into account the impact of newer and current RT techniques that are now available. Hence, this review aimed to evaluate the clinical evidence for each technique and determine the optimal radiation technique for ESNNBC treatment. Currently, six RT techniques are consistently used and studied: 1) prone positioning, 2) proton beam RT, 3) intensity-modulated RT, 4) breath-hold, 5) partial breast irradiation, and 6) intraoperative RT. These techniques show dosimetric promise. However, limited data on late cardiac and pulmonary events exist due to challenges in long-term follow-up. Moving forward, future studies are needed to validate the efficacy and clinical outcomes of these current techniques.

Design and Construction of A Laser-Based Respiratory Gating System For Implementation of Deep Inspiration Breathe Hold Technique in Radiotherapy Clinics

BACKGROUND

Deep inspiration breath-hold (DIBH) is known as a radiotherapy method for the treatment of patients with left-sided breast cancer. In this method, patient is under exposure only while he/she is at the end of a deep inspiration cycle and holds his/her breath. In this situation, the volume of the lung tissue is enhanced and the heart tissue is pushed away from the treating breast. Therefore, heart dose of these patients, using DIBH, experiences a considerable decline compared to free breathing treatment. There are a few commercialized systems for implementation of DIBH in invasive or noninvasive manners.

METHODS

We present a novel constructed noninvasive DIBH device relied on a manufacturing near-field laser distance meter. This in-house constructed system is composed of a CD22-100AM122 laser sensor combined with a data acquisition system for monitoring the breathing curve. Qt Creator (a cross-platform JavaScript, QML, and C++-integrated development environment that is part of the SDK for development of the Qt Graphical User Interface application framework) and Keil MDK-ARM (a programming software where users can write in C and C++ and assemble for ARM-based microcontrollers) are used for composing computer and microcontroller programs, respectively.

RESULTS

This system could be mounted in treatment or computed tomography (CT) room at suitable cost; it is also easy to use and needs a little training for personnel and patients. The system can assess the location of chest wall or abdomen in real time with high precision and frequency. The performance of CD22-100AM122 demonstrates promise for respiratory monitoring for its fast sampling rate as well as high precision. It can also deliver reasonable spatial and temporal accuracy. The patient observes his/her breathing waveform through a 7" 1024 × 600 liquid crystal display and gets some instructions during treatment and CT sessions by an exploited algorithm called "interaction scenario" in this study. The system is also noninvasive and well sustainable for patients.

CONCLUSIONS

The constructed system has true real-time operation and is rapid enough for delivering clear contiguous monitoring. In addition, in this system, we have provided an interaction scenario option between patient and CT or Linac operator. In addition, the constructed system has the capability of sending triggers for turning on and off CT or Linac facilities. In this concern, the system has the superiority of combining a plenty of characteristics.

Dosimetric comparison of deep-inspiration breath-hold and free-breathing treatment delivery techniques for left-sided breast cancer using 3D surface tracking

INTRODUCTION

While radiation therapy has been shown to increase local control and overall survival for breast cancer, late cardiac toxicity remains a concern. Morbidity and mortality have been shown to increase proportionally to the mean heart dose. Deep inspiration breath-hold (DIBH) can reduce heart dose compared to free-breathing (FB) by increasing the heart-to-chest wall distance, especially in left-sided breast cancer. We present our clinical experience with DIBH in left breast and chest-wall irradiation using 3D optical surface tracking.

MATERIALS & METHODS

29 patients were treated with DIBH using a surface tracking system that provides a real time 3D surface image of the patient. Comparisons of maximum and mean heart dose, heart-chest wall separation, and the percentage of lung volume that receives 20 or more Gy (V20) between the DIBH and hypothetical FB treatment plans were conducted with the Student's t-test. Correlation coefficients were also calculated for heart-chest wall separation, heart volume, and lung volume.

RESULTS

Comparing DIBH and FB plans showed a decrease in mean and maximum heart doses in all patients. Individual mean heart doses decreased by an average of 1.12 Gy, and the average mean heart dose for DIBH plans was significantly lower than corresponding FB plans (1.02 vs. 2.12 Gy; p < 0.0001). Maximum heart dose decreased by an average of 11.88 Gy and was significantly lower in DIBH versus FB plans (28.33 vs. 43.7 Gy; p = 0.0001). The average difference in heart to chest-wall separation between DIBH and FB images was 2.41 cm. DIBH left lung volume and measured increases in volume on inspiration inversely correlated with maximum heart dose (R = 0.39) and left lung V20 (R = 0.32).

CONCLUSIONS

DIBH with 3D surface tracking can significantly benefit patients with left sided disease by limiting the mean and maximum heart dose. DIBH appears to viably reduce heart dose for left-breast cancer patients and thus potentially reduce long-term complications without prolonging treatment delivery.

Cardiac sparing characteristics of internal mammary chain radiotherapy using deep inspiration breath hold for left-sided breast cancer

BACKGROUND

While breast radiotherapy typically includes regional nodal basins, the treatment of the internal mammary nodes (IMN) has been controversial due to concern for long-term cardiac toxicity. For high risk patients where IMN treatment is warranted, there is limited data with regards to the degree of heart sparing conferred by modern techniques. In this study, we sought to analyze the specific heart sparing metrics conferred by deep inspiration breath hold (DIBH) in the setting of IMN irradiation.

METHODS

From 2012 to 2015, 168 consecutive patients were treated with adjuvant left-sided radiotherapy using DIBH. Retrospective review identified 49 patients who received nodal irradiation, either to a supraclavicular field (SCF) and IMN (16), or to the SCF alone (33). Cardiac mean dose and dose volumes were calculated from free breathing (FB) and DIBH treatment plans, and compared by Wilcoxon signed-rank and Mann-Whitney U tests.

RESULTS

DIBH achieved significant reductions in mean heart dose (p < 0.001) in both the IMN treated group from 6.73 Gy to 2.79 Gy (- 56.4%) and the IMN untreated group from 4.77 Gy to 1.55 Gy (- 63.7%). There was a 7.3% difference in relative reduction that was not statistically significant (p = 0.216). Relative reductions in heart dose volume measures were all significantly lower for IMN-irradiated patients (p ≤ 0.012), with the greatest deficits at V₅ that gradually diminish with increasing dose (V₂₅).

CONCLUSIONS

The relative heart sparing benefits of the DIBH technique are retained even with IMN inclusion. However, the addition of IMN irradiation is associated with an intrinsically greater heart dose, which translates to an estimated 9.2% proportional increase in the risk of a subsequent major coronary event. In the setting of effective cardiac sparing techniques, clinicians should take these considerations into account to guide when IMN treatment is warranted.

Silent Neoplastic Cardiac Invasion in Small Cell Lung Cancer: A Case Report and Review of the Literature

Patient: Female, 66

Final Diagnosis: Small cell lung cancer

Symptoms: Impaired memory

Medication: —

Clinical Procedure: Chest X-ray • computed tomography • magnetic resonance imaging • electrocardiogram

Specialty: Oncology

Evaluation of a mixed beam therapy for postmastectomy breast cancer patients: Bolus electron conformal therapy combined with intensity modulated photon radiotherapy and volumetric modulated photon arc therapy

PURPOSE

The purpose of this study was to assess the potential benefits and limitations of a mixed beam therapy, which combined bolus electron conformal therapy (BECT) with intensity modulated photon radiotherapy (IMRT) and volumetric modulated photon arc therapy (VMAT), for left-sided postmastectomy breast cancer patients.

METHODS

Mixed beam treatment plans were produced for nine postmastectomy radiotherapy (PMRT) patients previously treated at our clinic with VMAT alone. The mixed beam plans consisted of 40 Gy to the chest wall area using BECT, 40 Gy to the supraclavicular area using parallel opposed IMRT, and 10 Gy to the total planning target volume (PTV) by optimizing VMAT on top of the BECT + IMRT dose distribution. The treatment plans were created in a commercial treatment planning system (TPS), and all plans were evaluated based on PTV coverage, dose homogeneity index (DHI), conformity index (CI), dose to organs at risk (OARs), normal tissue complication probability (NTCP), and secondary cancer complication probability (SCCP). The standard VMAT alone planning technique was used as the reference for comparison.

RESULTS

Both techniques produced clinically acceptable PMRT plans but with a few significant differences: VMAT showed significantly better CI (0.70 vs 0.53, P < 0.001) and DHI (0.12 vs 0.20, P < 0.001) over mixed beam therapy. For normal tissues, mixed beam therapy showed better OAR sparing and significantly reduced NTCP for cardiac mortality (0.23% vs 0.80%, P = 0.01) and SCCP for contralateral breast (1.7% vs 3.1% based on linear model, and 1.2% vs 1.9% based on linear-exponential model, P < 0.001 in both cases), but showed significantly higher mean (50.8 Gy vs 49.3 Gy, P < 0.001) and maximum skin doses (59.7 Gy vs 53.3 Gy, P < 0.001) compared with VMAT. Patients with more tissue (minimum distance between the distal PTV surface and lung approximately > 0.5 cm and volume of tissue between the distal PTV surface and heart or lung approximately > 250 cm³ ) between distal PTV surface and lung may benefit the most from mixed beam therapy.

CONCLUSION

This work has demonstrated that mixed beam therapy (BECT + IMRT:VMAT = 4:1) produces clinically acceptable plans having reduced OAR doses and risks of side effects compared with VMAT. Even though VMAT alone produces more homogenous and conformal dose distributions, mixed beam therapy remains as a viable option for treating postmastectomy patients, possibly leading to reduced normal tissue complications.

Target position reproducibility in left-breast irradiation with deep inspiration breath-hold using multiple optical surface control points

The aim of this study was to investigate the use of 3D optical localization of multiple surface control points for deep inspiration breath-hold (DIBH) guidance in left-breast radiotherapy treatments. Ten left-breast cancer patients underwent whole-breast DIBH radiotherapy controlled by the Real-time Position Management (RPM) system. The reproducibility of the tumor bed (i.e., target) was assessed by the position of implanted clips, acquired through in-room kV imaging. Six to eight passive fiducials were positioned on the patients' thoraco-abdominal surface and localized intrafractionally by means of an infrared 3D optical tracking system. The point-based registration between treatment and planning fiducials coordinates was applied to estimate the interfraction variations in patients' breathing baseline and to improve target reproducibility. The RPM-based DIBH control resulted in a 3D error in target reproducibility of 5.8 ± 3.4 mm (median value ± interquartile range) across all patients. The reproducibility errors proved correlated with the interfraction baseline variations, which reached 7.7 mm for the single patient. The contribution of surface fiducials registration allowed a statistically significant reduction (p < 0.05) in target localization errors, measuring 3.4 ± 1.7 mm in 3D. The 3D optical monitoring of multiple surface control points may help to optimize the use of the RPM system for improving target reproducibility in left-breast DIBH irradiation, providing insights on breathing baseline variations and increasing the robustness of external surrogates for DIBH guidance.

Deep Inspiration Breath Hold: Techniques and Advantages for Cardiac Sparing During Breast Cancer Irradiation

Historically, heart dose from left-sided breast radiotherapy has been associated with a risk of cardiac injury. Data suggests that there is not a threshold for the deleterious effects from radiation on the heart. Over the past several years, advances in radiation delivery techniques have reduced cardiac morbidity due to treatment. Deep inspiration breath hold (DIBH) is a technique that takes advantage of a more favorable position of the heart during inspiration to minimize heart doses over a course of radiation therapy. In the accompanying review article, we outline several methods used to deliver treatment with DIBH, quantify the benefits of DIBH treatment, discuss considerations for patient selection, and identify challenges associated with DIBH techniques.

The patient's perspective on breast radiotherapy: Initial fears and expectations versus reality

BACKGROUND

Although the efficacy and toxicity of breast radiotherapy (RT) has been studied extensively, to the authors' knowledge little is known regarding the patient's perspective on the modern breast RT experience. To better inform future patients and providers, the authors explored patient perceptions of their RT experience.

METHODS

Consecutive patients who were free of disease recurrence and who had been treated between 2012 and 2016 were surveyed regarding their original fears, how short-term and long-term toxicities compared with initial expectations, and how pretreatment beliefs concerning RT compared with the actual experience.

RESULTS

A total of 502 patients were surveyed, with a response rate of 65% (327 patients). The median patient age and posttreatment follow-up was 59 years and 31 months, respectively. Approximately 83% of patients (269 patients) underwent breast conservation therapy. Although approximately 68% of patients (221 patients) endorsed that they initially had little to no knowledge regarding RT, approximately 47% (152 patients) reported that they had heard frightening stories. Approximately 2% of patients (6 patients) agreed that the negative stories they previously heard about RT were actually true. Approximately 92% of patients treated with breast conservation (247 patients) and 81% of patients who underwent mastectomy (47 patients) agreed with the statement "If future patients knew the real truth about RT, they would be less scared about treatment." Approximately 83% (272 patients) and 84% (274 patients), respectively, of all patients reported the overall severity of short-term and long-term side effects to be better than or as expected.

CONCLUSIONS

Breast RT is associated with misconceptions and fears. Patients' experiences with modern breast RT appear to be superior to expectations, and the majority of patients in the current study agreed that their initial negative impressions were unfounded. Cancer 2018;124:1673-81. © 2018 American Cancer Society.

Dosimetric Evaluation of Critical Organs at Risk in Mastectomized Left-Sided Breast Cancer Radiotherapy Using Breath-Hold Technique

Aims and background

The aim of the study was to evaluate the dosimetric impact of the active breathing control-moderate deep inspiration breath-hold (ABC-mDIBH) technique on normal tissue sparing in locally advanced left-sided breast cancer radiotherapy.

Methods and study design

Twenty-seven consecutive patients with left-sided locally advanced breast cancer referred to our department for adjuvant radiotherapy were enrolled in the study. Each patient was scanned at free breathing and ABC-mDIBH for radiation treatment planning. Two separate radiotherapy treatment plans were generated with and without ABC-mDIBH to investigate the dosimetric impact of ABC-mDIBH in breast cancer radiotherapy.

Results

Between June 2011 and February 2012, 27 consecutive patients with left-sided locally advanced breast cancer referred to our department for adjuvant radiotherapy were enrolled in the study. Dose-volume parameters of left anterior descending coronary artery, lungs, heart, contralateral breast, esophagus and spinal cord were significantly reduced with the use of ABC-mDIBH ( P <0.001).

Conclusions

Our study revealed that the use of ABC-mDIBH in the practice of locally advanced mastectomized left-sided breast cancer radiotherapy improves normal tissue sparing with the expected potential of decreasing treatment-related morbidity and mortality. Moreover, the resultant reduction achieved with ABC in doses to the left anterior descending coronary artery, which plays a central role in cardiac perfusion, may have implications for decreasing the potential of radiation-induced cardiac morbidity and mortality.

Reproducible Deep-inspiration Breath-hold Irradiation with Forward Intensity-modulated Radiotherapy for Left-sided Breast Cancer Significantly Reduces Cardiac Radiation Exposure Compared to Inverse Intensity-modulated Radiotherapy

Aims and Background

To investigate the objective utility of our clinical routine of reproducible deep-inspiration breath-hold irradiation for left-sided breast cancer patients on reducing cardiac exposure.

Methods and Study Design

Free-breathing and reproducible deep-inspiration breath-hold scans were evaluated for our 10 consecutive left-sided breast cancer patients treated with reproducible deep-inspiration breath-hold. The study was based on the adjuvant dose of 50 Gy in 25 fractions of 2 Gy/fraction. Both inverse and forward intensity-modulated radiotherapy plans were generated for each computed tomography dataset.

Results

Reproducible deep-inspiration breath-hold plans with forward intensity-modulated radiotherapy significantly spared the heart and left anterior descending artery compared to generated free-breathing plans based on mean doses – free-breathing vs reproducible deep-inspiration breath-hold, left ventricle (296.1 vs 94.5 cGy, P = 0.005), right ventricle (158.3 vs 59.2 cGy, P = 0.005), left anterior descending artery (171.1 vs 78.1 cGy, P = 0.005), and whole heart (173.9 vs 66 cGy, P = 0.005), heart V20 (2.2% vs 0%, P = 0.007) and heart V10 (4.2% vs 0.3%, P = 0.007) – whereas they revealed no additional burden on the ipsilateral lung. Reproducible deep-inspiration breath-hold and free-breathing plans with inverse intensity-modulated radiotherapy provided similar organ at risk sparing by reducing the mean doses to the left ventricle, left anterior descending artery, heart, V10-V20 of the heart and right ventricle. However, forward intensity-modulated radiotherapy showed significant reduction in doses to the left ventricle, left anterior descending artery, heart, right ventricle, and contralateral breast (mean dose, 248.9 to 12.3 cGy, P = 0.005). The mean doses for free-breathing vs reproducible deep-inspiration breath-hold of the proximal left anterior descending artery were 1.78 vs 1.08 Gy and of the distal left anterior descending artery were 8.11 vs 3.89 Gy, whereas mean distances to the 50 Gy isodose line of the proximal left anterior descending artery were 6.6 vs 3.3 cm and of the distal left anterior descending artery were 7.4 vs 4.1 cm, with forward intensity-modulated radiotherapy. Overall reduction in mean doses to proximal and distal left anterior descending artery with deep-inspiration breath-hold irradiation was 39% (P = 0.02) and 52% (P = 0.002), respectively.

Conclusions

We found a significant reduction of radiation exposure to the contralateral breast, left and right ventricles, as well as of proximal and especially distal left anterior descending artery with the deep-inspiration breath-hold technique with forward intensity-modulated radiotherapy planning.

Patient-reported outcomes of catheter-based accelerated partial breast brachytherapy and whole breast irradiation, a single institution experience

PURPOSE

Accelerated partial breast irradiation (APBI) and whole breast irradiation (WBI) are treatment options for early-stage breast cancer. The purpose of this study was to compare patient-reported-outcomes (PRO) between patients receiving multi-channel intra-cavitary brachytherapy APBI or WBI.

METHODS

Between 2012 and 2015, 131 patients with ductal carcinoma in situ (DCIS) or early stage invasive breast cancer were treated with adjuvant APBI (64) or WBI (67) and participated in a PRO questionnaire. The linear analog scale assessment (LASA), harvard breast cosmesis scale (HBCS), PRO-common terminology criteria for adverse events- PRO (PRO-CTCAE), and breast cancer treatment outcome scale (BCTOS) were used to assess quality of life (QoL), pain, fatigue, aesthetic and functional status, and breast cosmesis. Comparisons of PROs were performed using t-tests, Wilcoxon rank-sum, Chi square, Fisher exact test, and regression methods.

RESULTS

Median follow-up from completion of radiotherapy and questionnaire completion was 13.3 months. There was no significant difference in QoL, pain, or fatigue severity, as assessed by the LASA, between treatment groups (p > 0.05). No factors were found to be predictive of overall QoL on regression analysis. BCTOS health-related QoL scores were similar between treatment groups (p = 0.52).The majority of APBI and WBI patients reported excellent/good breast cosmesis, 88.5% versus 93.7% (p = 0.37). Skin color change (p = 0.011) and breast elevation (p = 0.01) relative to baseline were more common in the group receiving WBI.

CONCLUSIONS

APBI and WBI were both associated with favorable patient-reported outcomes in early follow-up. APBI resulted in a lesser degree of patient-reported skin color change and breast elevation relative to baseline.

The impact of semilateral decubitus position on the dose-volume parameters of the heart and lung for left sided breast cancer patients: A comparative dosimetric study

PURPOSE

When treating breast cancer with radiation therapy, the impact of treatment position on heart and lung dose-volume parameters (DVPs) is largely dependent on the maximal heart distance (MHD) and central lung distance (CLD). We evaluate how much heart and lung sparing can be achieved using the semilateral decubitus (SLD) position without and with breath hold compared with the standard supine position for left-sided breast cancer patients. A secondary aim was to investigate the impact of MHD and CLD on heart and lung DVPs.

METHODS AND MATERIALS

Thirty-five left-sided breast cancer patients were simulated in supine, free breathing SLD, and SLD with breath hold positions. A dosimetry plan was developed for each of these and 3 plans were compared for target coverage and organs at risk sparing. A correlation between CLD, MHD, and planning target volume, and heart and ipsilateral lung DVPs was tested.

RESULTS

SLD breath hold position showed a significant reduction in percentage of heart receiving ≥5 Gy (V_5Gy), V_10Gy, V_25Gy, V_30Gy, mean dose and maximum dose (P < .001), ipsilateral lung V_20Gy, and mean dose compared with supine (P < 001) and free breathing SLD (P = .003 and .006). There was also a significant reduction in the heart DVPs (P < .001) and ipsilateral lung DVPs (P < .001 and .007) with free breathing SLD compared with the supine position. SLD with or without breath hold were associated with significant reduction in MLD (P < .001) and CLD (P = .030 and .003) compared with the supine position.

CONCLUSION

Treatment plans for patients in the SLD position with or without breath hold for left-sided breast cancer patients demonstrated a superior heart and lung sparing compared with the supine position due to significant reduction in MHD and CLD. MHD and CLD are important simulation factors that affect the heart and lung DVP.

Field-Specific Intensity-modulated Proton Therapy Optimization Technique for Breast Cancer Patients with Tissue Expanders Containing Metal Ports

This report aims to propose and present an evaluation of a robust pencil beam scanning proton multi-field optimized treatment planning technique for postmastectomy radiation of breast cancer patients with implanted tissue expanders containing an internal metal port. Field-specific split targets were created for optimization to prevent spots from traveling through the metal port, while providing uniform coverage of the target with the use of a multi-field intensity modulated optimization approach. Two beam angles were strategically selected to provide complementary target coverage and plan robustness. The plan was compared with an independently developed photon plan and evaluated for robustness with respect to isocenter shifts, range shifts, and variation of the water-equivalent thickness of the port. The proton plan resulted in clinically acceptable target coverage and dosage to neighboring normal tissues. The D95% coverage was 95.3% in the nominal proton plan, with a worst-case coverage of 90.1% (when considering 0.3 cm isocenter shifts combined with 3.5% range uncertainty), and the coverage varied less than 1% under a hypothetically extreme variation of the port density. The proton plan had improved dose homogeneity compared with the photon plan, and reduced ipsilateral lung and mean heart doses. We demonstrated that a practical, field-specific intensity-modulated proton therapy (IMPT) optimization technique can be used to deal with the challenge of metal port in breast cancer patients with tissue expanders. The resulting proton plan has superior dosimetric characteristics over the best-case scenario photon plan, and is also robust to setup and proton range uncertainties.

Selection of patients with left breast cancer for deep-inspiration breath-hold radiotherapy technique: Results of a prospective study

AIM

To assess prospectively which patients with left breast cancer have the dosimetric benefit from the use of deep-inspiration breath-hold radiotherapy (DIBH-RT).

BACKGROUND

Improvement in selection of patients for DIBH-RT would spare time of radiotherapy staff by removing the need for preparation of two comparative treatment plans.

MATERIALS AND METHODS

Thirty-one patients qualified for whole left breast irradiation underwent breath-hold training and their free-breathing (FB) and DIBH planning-CT were included in the analysis of dosimetric outcome. Mean heart dose (MHD), heart V20 Gy (V20Heart), maximum dose to LAD (LADmax), V20 for left lung (V20L.lung) were recorded from FB and DIBH plans and the differences (Δ) of these values were calculated. If relative improvement of at least 20% for any evaluated dosimetric parameter was found for the DIBH-RT, this plan was selected for treatment. Correlations of Δ of dosimetric parameters with patient-related parameters (BMI, age, PTV, cardiac contact distance [CCD], lung volume at FB) were sought.

RESULTS

In 30 of 31 patients, a predefined reduction in evaluated parameters was achieved. CCD, BMI correlated positively with ΔMHD, ΔV20Heart, ΔLADmax; PTV with ΔMHD and ΔV20Heart (p < 0.05; AUC > 0.6); Lung volume correlated negatively with ΔLADmax, ΔMHD and ΔV20Heart. No specific thresholds for the lack of predefined improvement of any dosimetric parameters was identified in ROC analysis. 19/30 (63%) patients with dosimetric benefit completed their RT with DIBH.

CONCLUSIONS

Despite a strong correlation between patient-related and dosimetric parameters, we cannot use the anatomical characteristics' thresholds to select patients for whom DIBH-RT will not be considered.

Cardiac Dose Reduction with Deep-Inspiratory Breath Hold Technique of Radiotherapy for Left-Sided Breast Cancer

INTRODUCTION

Different techniques of radiation therapy have been studied to reduce the cardiac dose in left breast cancer.

AIM

In this prospective dosimetric study, the doses to heart as well as other organs at risk (OAR) were compared between free-breathing (FB) and deep inspiratory breath hold (DIBH) techniques in intensity modulated radiotherapy (IMRT) and opposed-tangent three-dimensional radiotherapy (3DCRT) plans.

MATERIALS AND METHODS

Fifteen patients with left-sided breast cancer underwent computed tomography simulation and images were obtained in both FB and DIBH. Radiotherapy plans were generated with 3DCRT and IMRT techniques in FB and DIBH images in each patient. Target coverage, conformity index, homogeneity index, and mean dose to heart (Heart Dmean), left lung, left anterior descending artery (LAD) and right breast were compared between the four plans using the Wilcoxon signed rank test.

RESULTS

Target coverage was adequate with both 3DCRT and IMRT plans, but IMRT plans showed better conformity and homogeneity. A statistically significant dose reduction of all OARs was found with DIBH. 3DCRTDIBH decreased the Heart Dmean by 53.5% (7.1 vs. 3.3 Gy) and mean dose to LAD by 28% compared to 3DCRTFB. IMRT further lowered mean LAD dose by 18%. Heart Dmean was lower with 3DCRTDIBH over IMRTDIBH (3.3 vs. 10.2 Gy). Mean dose to the contralateral breast was also lower with 3DCRT over IMRT (0.32 vs. 3.35 Gy). Mean dose and the V20 of ipsilateral lung were lower with 3DCRTDIBH over IMRTDIBH (13.78 vs. 18.9 Gy) and (25.16 vs. 32.95%), respectively.

CONCLUSIONS

3DCRTDIBH provided excellent dosimetric results in patients with left-sided breast cancer without the need for IMRT.

Ischemic Cardiac Events Following Treatment of the Internal Mammary Nodal Region Using Contemporary Radiation Planning Techniques

PURPOSE

Regional nodal irradiation, including radiation therapy (RT) to the internal mammary node (IMN) region, improves oncologic outcomes in patients with node-positive breast cancer. Concern remains, however, given the proximity of the IMNs to the heart and the association between cardiac RT exposure and toxicity. The objective of the study was to evaluate rates of ischemic cardiac events (ICEs) and associated risk with treatment of the IMN region.

METHODS AND MATERIALS

The cardiac outcomes of 2126 patients treated with adjuvant breast RT or breast and nodal RT from 1984 to 2007 at a single institution were reviewed. The primary endpoint was an ICE following RT initiation. The association between IMN RT and ICEs was assessed using Cox proportional hazards models. Treatment with both IMN RT and 3-dimensional (3D) conformal radiation therapy (CRT) began in 1997; therefore, subset analyses of patients with only 3D CRT were performed to minimize bias associated with improved treatment technique.

RESULTS

The median follow-up period was 9.3 years. An ICE occurred in 87 patients (4.1%). No increased 10-year rate of ICEs was observed with IMN RT compared with no IMN RT in the total cohort (3.2% [95% confidence interval (CI), 2.4%-4.3%] vs 3.4% [95% CI, 1.5%-7.5%]; hazard ratio [HR], 0.88; P=.73). Similarly, no statistically significant difference was noted in the 3D CRT-planned, left-sided disease subset (5.1% [95% CI, 1.8%-14.1%] vs 4.0% [95% CI, 2.0%-8.0%]; HR, 1.18, P=.76). On multivariate analysis, adjusting for cardiac risk factor imbalances, no significantly increased hazard was noted with IMN RT (HR, 1.84; P=.28) in the 3D CRT-planned, left-sided disease subset.

CONCLUSIONS

No statistically significant association between IMN RT and ICEs was demonstrated in a review of patients treated at a single institution from 1984 to 2007. Given the long natural history and low overall rate of ICEs, continued follow-up of this study, as well as additional studies in the 3D CRT era, is warranted to confirm these results. Minimizing cardiac exposure, when treating a limited IMN field, is critical to limit excess risk of ICEs.

An effective deep-inspiration breath-hold radiotherapy technique for left-breast cancer: impact of post-mastectomy treatment, nodal coverage, and dose schedule on organs at risk

Background

We developed, applied, and prospectively evaluated a novel deep-inspiration breath-hold (DIBH) screening and delivery technique to optimize cardiac sparing in left-breast radiotherapy (RT) at our clinic. The impact of set-up and dose variables upon organs at risk (OAR) dose in DIBH RT was investigated.

Methods and materials

All patients with left-breast cancer referred between 2011 and 2014 – of all disease stages, set-up variations, and dose prescriptions – were included. Radiographers used simple screening criteria at CT simulation, to systematically assess patients for obvious DIBH benefit and capability. Selected patients received forward-planned intensity-modulated RT (IMRT) based on a DIBH CT scan. A 3D-surface monitoring system with visual feedback assured reproducible DIBH positioning during gated radiation delivery. Patient, target set-up, and OAR dose information were collected at treatment.

Results

Of 272 patients who were screened, 4 withdrew, 56 showed no obvious advantage, and 56 showed benefit but had suitability issues; 156 patients were selected and successfully completed DIBH treatment. The technique was compatible with complex set-up and optimal target coverage was maintained. Comparison of free-breathing (FB) and DIBH treatment plans in the first five patients enrolled confirmed DIBH reduced heart radiation by ~80% (p = 0.032). Low OAR doses were achieved overall: the mean (95% confidence interval [CI]) heart dose was 1.17 (1.12–1.22) Gy, and the mean ipsilateral lung dose was 5.26 (5.01–5.52) Gy. Patients who underwent a standard radiation schedule (40 Gy/15#) after breast-conserving surgery had the lowest OAR doses: post-mastectomy treatment, simultaneous supraclavicular (SCV) node coverage, and alternative dose schedule (50 Gy/25#) were interrelated variables associated with increased OAR risk and compromised ipsilateral lung dose constraints.

Conclusion

The DIBH technique was successfully implemented and resulted in optimally low heart radiation. All patients who demonstrate sufficient DIBH technique at planning CT are now offered DIBH RT at our clinic. Patients with more advanced disease, particularly those with additional pulmonary risk factors, warrant additional focus to improve lung sparing.

Is it possible for knowledge-based planning to improve intensity modulated radiation therapy plan quality for planners with different planning experiences in left-sided breast cancer patients?

Background

Knowledge-based planning (KBP) is a promising technique that can improve plan quality and increase planning efficiency. However, no attempts have been made to extend the domain of KBP for planners with different planning experiences so far. The purpose of this study was to quantify the potential gains for planners with different planning experiences after implementing KBP in intensity modulated radiation therapy (IMRT) plans for left-sided breast cancer patients.

Methods

The model libraries were populated with 80 expert clinical plans from treated patients who previously received left-sided breast-conserving surgery and IMRT with simultaneously integrated boost. The libraries were created on the RapidPlan^TM. 6 planners with different planning experiences (2 beginner planners, 2 junior planners and 2 senior planners) generated manual and KBP optimized plans for additional 10 patients, similar to those included in the model libraries. The plan qualities were compared between manual and KBP plans.

Results

All plans were capable of achieving the prescription requirement. There were almost no statistically significant differences in terms of the planning target volume (PTV) coverage and dose conformality. It was demonstrated that the doses for most of organs-at-risk (OARs) were on average lower or equal in KBP plans compared to manual plans except for the senior planners, where the very small differences were not statistically significant. KBP data showed a systematic trend to have superior dose sparing at most parameters for the heart and ipsilateral lung. The observed decrease in the doses to these OARs could be achieved, particularly for the beginner and junior planners. Many differences were statistically significant.

Conclusions

It is feasible to generate acceptable IMRT plans after implementing KBP for left-sided breast cancer. KBP helps to effectively improve the quality of IMRT plans against the benchmark of manual plans for less experienced planners without any manual intervention. KBP showed promise for homogenizing the plan quality by transferring planning expertise from more experienced to less experienced planners.

Intensity modulated radiotherapy with fixed collimator jaws for locoregional left-sided breast cancer irradiation

The purpose of this study is to evaluate the intensity modulated radiotherapy (IMRT) with the fixed collimator jaws technique (FJT) for the left breast and regional lymph node. The targeted breast tissue and the lymph nodes, and the normal tissues were contoured for 16 left-sided breast cancer patients previously treated with radiotherapy after lumpectomy. For each patient, treatment plans using different planning techniques, i.e., volumetric modulated arc therapy (VMAT), tangential IMRT (tangential-IMRT), and IMRT with FJT (FJT-IMRT) were developed for dosimetric comparisons. A dose of 50Gy was prescribed to the planning target volume. The dose-volume histograms were generated, and the paired t-test was used to analyze the dose differences. FJT-IMRT had similar mean heart volume receiving 30Gy (V30 Gy) with tangential-IMRT (1.5% and 1.6%, p = 0.41), but inferior to the VMAT (0.8%, p < 0.001). In the average heart mean dose comparison, FJT-IMRT had the lowest value, and it was 0.6Gy lower than that for the VMAT plans (p < 0.01). A significant dose increase in the contralateral breast and lung was observed in VMAT plans. Compared with tangential-IMRT and VMAT plans, FJT-IMRT reduced the mean dose of thyroid, humeral head and cervical esophageal by 47.6% (p < 0.01) and 45.7% (p < 0.01), 74.3% (p = < 0.01) and 73% (p = < 0.01), and 26.7% (p = < 0.01) and 29.2% (p = < 0.01). In conclusion, compared with tangential-IMRT and VMAT, FJT-IMRT plan has the lowest thyroid, humeral head and cervical esophageal mean dose and it can be a reasonable treatment option for a certain subgroup of patients, such as young left-breast cancer patients and/or patients with previous thyroid disease.

Heart-sparing radiotherapy in patients with breast cancer: What are the techniques used in the clinical routine?: A pattern of practice survey in the German-speaking countries

The aim of this study was to understand the practice of care in German-speaking countries with regard to heart-sparing radiotherapy techniques. Between August 2015 and September 2015, an e-mail/fax-based survey was sent to radiation oncology departments in Germany, Austria, and the German-speaking Switzerland. The questionnaire was divided into 3 chapters: a general chapter on the department, a chapter specific for heart-sparing techniques in patients with breast cancer, and a third chapter on personal beliefs on the topic of heart sparing in patients with breast cancer. A total of 82 radiation oncology departments answered the questionnaire: 16 university clinics and 66 other departments. In general, heart-sparing techniques are being offered by 90.2% of departments for radiation oncology in the German-speaking countries. However, in the clinical routine, 87.7% of institutions use heart-sparing techniques in less than 50% of patients with breast cancer. Heart-sparing techniques are especially provided for patients with left-sided breast cancer (80%), patients after mastectomy (52.5%), and when the mammaria interna lymph drainage vessels are irradiated (41.3%). In 46.3% of departments, there are written internal guidelines for heart sparing in patients with breast cancer. Breathing-adapted radiotherapy is used as the most frequent heart-sparing technique in 64.7% of the institutions, followed by intensity-modulated radiation therapy, which is most frequently used by 22.1%. The only significant difference between university hospitals and other departments was seen for the offering of partial breast irradiation. The most commonly used heart-sparing technique is breathing-adapted radiotherapy, but there is no coherent approach for heart sparing in patients with breast cancer in the German-speaking countries. Overall, all options for cardiac protection/cardiac avoidance have their advantages and disadvantages, with deep inspiration breath-hold radiotherapyhaving the most clear data, which should be the preferred choice when using heart-sparing techniques.

Deep inspiration breathhold for left-sided breast cancer patients with unfavorable cardiac anatomy requiring internal mammary nodal irradiation

PURPOSE

The purpose of this study was to evaluate the utility of moderate deep inspiration breathhold (mDIBH) in reducing heart exposure in left breast cancer patients who have unfavorable cardiac anatomy and need internal mammary lymph node (IMLN) radiation therapy (RT).

METHODS AND MATERIALS

We used maximum heart distance (MHD), defined as the maximum distance of the heart within the treatment field, >1 cm as a surrogate for unfavorable cardiac anatomy. Twenty-two left breast cancer patients with unfavorable cardiac anatomy requiring IMLN-RT underwent free-breathing (FB) and mDIBH computed tomography simulation and planning. Three-dimensional partially wide tangents (3D-PWTs) and intensity modulated RT plans were generated. Dose-volume histograms were used to compare heart and lung dosimetric parameters. Duration of treatment delivery was recorded for all fractions.

RESULTS

MHD decreased significantly in mDIBH scans. mDIBH significantly reduced mean heart dose (222.7 vs 578.4 cGy; P < .0001) and percentage of left lung receiving doses ≥20 Gy (V20; 31.93 vs 38.41%; P = .0006) in both 3D-PWT and intensity modulated RT plans. The change in MHD after breathhold reliably predicted mean heart dose reduction after mDIBH. Radiation was effectively delivered in 11.31 ± 3.40 minutes with an average of 10.06 ± 2.74 breathholds per fraction.

CONCLUSIONS

mDIBH is efficient and can effectively decrease mean heart dose in patients with unfavorable cardiac anatomy who need IMLN-RT, thus simplifying planning and delivery for them. The reduction in mean heart dose is proportional to the reduction in maximum heart distance.

Restrictive cardiomyopathy : Delayed occurrence after radiotherapy of breast cancer

A 74-year-old female patient was referred to our department in 2015 with dyspnea, cough and dysphagia. She had been diagnosed with adenocarcinoma of the right breast in 1986 and underwent mastectomy. When she presented with a local recurrence in 1988, she was receiving high-voltage radiation therapy. Transthoracic echocardiography and magnetic resonance imaging revealed tricuspid regurgitation grade III and unclear right heart failure with a massively dilated right atrium. Coronary heart disease could be ruled out. In summary, the patient's findings represented right ventricular myocardial restriction which we attributed to irradiation of the right anterior chest 17 years previously.

Deep inspiration breath-hold produces a clinically meaningful reduction in ipsilateral lung dose during locoregional radiation therapy for some women with right-sided breast cancer

PURPOSE

The goal of the work described here was to determine whether deep inspiration breath-hold (DIBH) produces a clinically meaningful reduction in pulmonary dose compared with free breathing (FB) during locoregional radiation for right-sided breast cancer.

METHODS AND MATERIALS

Four-field, modified-wide tangent plans with full nodal coverage were developed for 30 consecutive patients on paired DIBH and FB CT scans. Nodes were contoured according to European Society for Radiotherapy and Oncology guidelines. Plan metrics were compared using Wilcoxon signed-rank testing.

RESULTS

In 21 patients (70%), there was a ≥5% reduction in ipsilateral lung V20Gy with DIBH compared with FB. The mean decrease in ipsilateral lung V20Gy was 7.8% (0%-20%, P < .001). The mean lung dose decreased on average by 3.4 Gy with DIBH (-0.2 to 9.1, P < .001). The mean reduction in liver volume receiving 50% of the prescribed dose was 42.3 cm³ (0-178.9 cm³, P < .001).

CONCLUSIONS

DIBH reduced ipsilateral lung V20Gy by ≥5% in the majority of patients. For some patients, the volume of liver receiving a potentially toxic dose decreased with DIBH. DIBH should be available as a treatment strategy to reduce ipsilateral lung V20Gy prior to compromising internal mammary chain nodal coverage for patients with right-sided breast cancer during locoregional radiation therapy if the V20Gy on FB exceeds 30%.

Translucent poly(vinyl alcohol) cryogel dosimeters for simultaneous dose buildup and monitoring during chest wall radiation therapy

Chest wall radiation therapy treatment delivery was monitored using a 5 mm thick radiochromic poly(vinyl alcohol) cryogel that also provided buildup material. The cryogels were used to detect positioning errors and measure the impact of shifts for a chest wall treatment that was delivered to a RANDO phantom. The phantom was shifted by ± 2, ± 3, and ± 5 mm from the planned position in the anterior/posterior (A/P) direction; these shifts represent setup errors and the uncertainty associated with lung filling during breath-hold. The two-dimensional absolute dose distributions measured in the cryogel at the planned position were compared with the distributions at all shifts from this position using gamma analysis (3%/3 mm, 10% threshold). For shifts of ± 2, ± 3, and ± 5 mm the passing rates ranged from 94.3% to 95.6%, 74.0% to 78.8%, and 17.5% to 22.5%, respectively. These results are consistent with the same gamma analysis performed on dose planes calculated in the middle of the cryogel and on the phantom surface using our treatment plan-ning system, which ranged from 94.3% to 95.0%, 76.8% to 77.9%, and 23.5% to 24.3%, respectively. The Pinnacle dose planes were then scaled empirically and compared to the cryogel measurements. Using the same gamma metric, the pass rates ranged from 97.0% to 98.4%. The results of this study suggest that cryogels may be used as both a buildup material and to evaluate errors in chest wall treat-ment positioning during deep-inspiration breath-hold delivery. The cryogels are sensitive to A/P chest wall shifts of less than 3 mm, which potentially allows for the detection of clinically relevant errors.

[Respiratory synchronization and breast radiotherapy]

Adjuvant radiation therapy following breast cancer surgery continues to improve locoregional control and overall survival. But the success of highly targeted-conformal radiotherapy such as intensity-modulated techniques, can be compromised by respiratory motion. The intrafraction motion can potentially result in significant under- or overdose, and also expose organs at risk. This article summarizes the respiratory motion and its effects on imaging, dose calculation and dose delivery by radiotherapy for breast cancer. We will review the methods of respiratory synchronization available for breast radiotherapy to minimize the respiratory impact and to spare organs such as heart and lung.

Dosimetric Considerations in Respiratory-Gated Deep Inspiration Breath-Hold for Left Breast Irradiation

PURPOSE

To present our clinical workflow of incorporating AlignRT for left breast deep inspiration breath-hold treatments and the dosimetric considerations with the deep inspiration breath-hold protocol.

MATERIAL AND METHODS

Patients with stage I to III left-sided breast cancer who underwent lumpectomy or mastectomy were considered candidates for deep inspiration breath-hold technique for their external beam radiation therapy. Treatment plans were created on both free-breathing and deep inspiration breath-hold computed tomography for each patient to determine whether deep inspiration breath-hold was beneficial based on dosimetric comparison. The AlignRT system was used for patient setup and monitoring. Dosimetric measurements and their correlation with chest wall excursion and increase in left lung volume were studied for free-breathing and deep inspiration breath-hold plans.

RESULTS

Deep inspiration breath-hold plans had significantly increased chest wall excursion when compared with free breathing. This change in geometry resulted in reduced mean and maximum heart dose but did not impact lung V₂₀ or mean dose. The correlation between chest wall excursion and absolute reduction in heart or lung dose was found to be nonsignificant, but correlation between left lung volume and heart dose showed a linear association. It was also identified that higher levels of chest wall excursion may paradoxically increase heart or lung dose.

CONCLUSION

Reduction in heart dose can be achieved for many left-sided breast and chest wall patients using deep inspiration breath-hold. Chest wall excursion as well as left lung volume did not correlate with reduction in heart dose, and it remains to be determined what metric will provide the most optimal and reliable dosimetric advantage.

The benefit of deep inspiration breath hold: evaluating cardiac radiation exposure in patients after mastectomy and after breast-conserving surgery

BACKGROUND

This study aims to evaluate the reduction of cardiac radiation dose and volume with deep inspiration breath hold (DIBH) technique compared to free breathing (FB) in patients with left-sided breast cancer. The study also aims to evaluate whether the benefits of DIBH vary in patients who had whole breast radiotherapy (RT) after breast-conserving surgery (BCS) and those who had chest wall RT post-mastectomy (M).

METHODS

FB and DIBH plans were generated for 15 consecutive post-BCS patients and 17 post-M patients who underwent RT with DIBH using varian real-time position management (RPM) system. Cardiac shields were used in all post-BCS plans, provided that clinical treatment volume coverage was not compromised, while chest wall coverage took priority in post-M plans. The prescribed dose was 50 Gy in 25 fractions for the whole breast or the chest wall. Parameters of interest were cardiac V5, mean LAD dose, maximum LAD dose, and mean heart dose. The impact of DIBH was compared in post-BCS and post-M patients using paired t tests. To gauge clinically meaningful outcome, the proportion of patients with V5 < 5 % and mean cardiac dose <2 Gy were compared using McNemar's test.

RESULTS

DIBH decreased V5 by an absolute 4.5 % (2.3 vs. 6.8 %; p < 0.0001) in post-M group, and by an absolute 2.4 % (1.3 vs. 3.7 %; p = 0.0028) in post-BCS group. DIBH decreased the mean heart dose by 107.0 cGy (127.4 vs. 234.4 cGy; p = 0.0002) in post-M group, and by 58.9 cGy (82.2 vs. 141.1 cGy; p = 0.0012) in post-BCS group. DIBH decreased mean LAD by 1201.6 cGy (670 vs. 1872.5 cGy; p = 0.0006) in post-M group, and by 799.0 cGy (425.3 vs. 1224.3 cGy; p = 0.0003) in post-BCS group. DIBH also decreased max LAD dose by 1244.3 cGy (2776.0 vs. 4020.3 cGy; p = 0.0014) in post-M group, and by 1856.3 cGy (1898.7 vs. 3754.9 cGy; p = 0.0005) in post-BCS group. In post-BCS group, cardiac V5 < 5 % was achieved in 10/15 (67 %) FB patients, and in 15/15 (100 %) DIBH patients (p = 0.002), and mean heart dose <2 Gy was achieved in 12/15 (80 %) FB patients and in 15/15 (100 %) DIBH patients (p < 0.001). This compares with post-M group, in which V5 < 5 % was achieved in 6/17 (35 %) FB patients and in 16/17 (94 %) DIBH patients (p = 0.05), and mean heart dose <2 Gy was achieved in 7/17 FB (41 %) an 16/17 DIBH patients (94 %) (p = 0.03).

CONCLUSION

The results of this study suggest that there is considerable reduction in cardiac exposure in most patients with DIBH compared to FB, although less reduction is observed in the post-BCS patients. The use of cardiac shields and collimators/gantry adjustments, more readily applicable for post-BCS cases, may limit the additional benefits of DIBH. In an environment where DIBH availability is limited, the result of this study supports the preferential use of DIBH in post-M patients over post-BCS patients.

Stereotactic radiotherapy for the treatment of lung cancer with a giant left atrial tumor thrombus: A case report and literature review

Lung cancer presenting with a giant atrial tumor thrombus is particularly rare. Surgical resection, aided by a cardiopulmonary bypass, is the standard treatment of choice if there is no distant metastasis. However, this form of surgery carries a high risk, with the subsequent patient prognosis being extremely poor. The current study describes the case of a 52-year-old man presenting with left lung squamous cell carcinoma that had extended into the left atrium. The patient was treated with stereotactic radiotherapy, and regarding the atrial disease, a complete response was achieved within 12 months. The present case demonstrates that stereotactic radiotherapy may be a beneficial palliative treatment for patients with stage IV lung cancer invading the left atrium.