Helical tomotherapy and volumetric modulated arc therapy: New therapeutic arms in the breast cancer radiotherapy

Evaluation of Ethos intelligent optimization engine for left locally advanced breast cancer

Purpose

To evaluate the feasibility to use a standard Ethos planning template to treat left-sided breast cancer with regional lymph nodes.

Material/Methods

The tuning cohort of 5 patients was used to create a planning template. The validation cohort included 15 patients treated for a locally advanced left breast cancer randomly enrolled. The Ethos planning template was tuned using standard 3 partial arc VMAT and two collimator rotation configurations: 45/285/345° and 30/60/330°. Re-planning was performed automatically using the template without editing. The study was conducted with a schedule of 42.3 Gy in 18 fractions to the breast/chestwall, internal mammary chain (IMC) and regional lymph nodes ("Nodes"). The PTV was defined as a 3D extension of the CTV with a margin of 7 mm, excluding the 5mm below the skin. The manual treatment plans were performed using Eclipse treatment planning system with AAA and PO algorithms (v15.6) and a manual arc VMAT configuration and imported in Ethos TPS (v1.1) for a dose calculation with Ethos Acuros algorithm. The automated plans were compared with the manual plans using PTV and CTV coverage, homogeneity and conformity indices (HI and CN) and doses to organs at risk (OAR) via DVH metrics. For each plan, the patient quality assurance (QA) were performed using Mobius3D and gamma index. Finally, two breast radiation oncologists performed a blinded assessment of the clinical acceptability of each of the three plans (manual and automated) for each patient.

Results

The manual and automated plans provided suitable treatment planning as regards dose constraints. The dosimetric comparison showed the CTV_breast D99% were significantly improved with both automated plans (p< 0,002) while PTV coverage was comparable. The doses to the organs at risk were equivalent for the three plans. Concerning treatment delivery, the Ethos-45° and Ethos-30° plans led to an increase in MUs compared to the manual plans, without affecting the beam on time. The average gamma index pass rates remained consistently above 98% regardless of the type of plan utilized. In the blinded evaluation, clinicians 1 and 2 assessed 13 out of 15 plans for Ethos 45° and 11 out of 15 plans for Ethos 30° as clinically acceptable.

Conclusion

Using a standard planning template for locally advanced breast cancer, the Ethos TPS provided automated plans that were clinically acceptable and comparable in quality to manually generated plans. Automated plans also dramatically reduce workflow and operator variability.

A Comparative Analysis of Implant-sparing Plan Versus Conventional Plans Utilizing Helical Tomotherapy in Breast Cancer Patients Undergoing Breast Reconstruction

BACKGROUND/AIM

To compare implant sparing irradiation with conventional radiotherapy (RT) using helical (H) and TomoDirect (TD) techniques in breast cancer patients undergoing immediate breast reconstruction (IBR).

PATIENTS AND METHODS

The dosimetric parameters of 40 patients with retropectoral implants receiving 50.4 Gy delivered in 28 fractions were analyzed. Three plans were created: H plan using conventional planning target volume (PTV) that included the chest wall, skin, and implant; TD plan using conventional PTV; and Hs plan using implant-sparing PTV. The H, TD, and Hs plans were compared for PTV doses, organ-at-risk (OAR) doses, and treatment times.

RESULTS

Dose distribution in the Hs plan was less homogeneous and uniform than that in the H and TD plans. The TD plan had lower lung, heart, contralateral breast, spinal cord, liver, and esophagus doses than the Hs plan. Compared to the Hs plan, the H plan had lower lung volume receiving 5Gy (V5) (39.1±3.9 vs. 41.2±3.9 Gy; p<0.001), higher V20 (12.3±1.3 vs. 11.5±2.6 Gy; p=0.02), and higher V30 (7.5±1.6 vs. 4.4±1.7 Gy; p<0.001). H plan outperformed Hs plan in heart dosimetric parameters except V20. The Hs plan had significantly lower mean implant doses (43.4±2.1 Gy) than the H plan (51.4±0.5 Gy; p<0.001) and the TD plan (51.9±0.6 Gy; p<0.001). Implementing an implant sparing technique for silicone dose reduction decreases lung doses.

CONCLUSION

Conventional H and TD plans outperform the implant sparing helical plan dosimetrically. Because capsular contracture during RT is unpredictable, long-term clinical outcomes are required to determine whether silicon should be spared.

Comparative dosimetric and radiobiological assessment of left-sided whole breast and regional nodes with advanced radiotherapy techniques

The aim of this study was to analyze the dosimetric and radiobiologic differences of the left-sided whole breast and regional nodes in intensity-modulated radiotherapy (IMRT), volume-modulated arc therapy (VMAT), and helical tomotherapy (HT).  The IMRT, VMAT, and HT plans in this study were generated for thirty-five left-sided breast cancer patients after breast-conserving surgery (BCS). The planning target volume (PTV) included the whole breast and supraclavicular nodes. PTV coverage, homogeneity index (HI), conformity index (CI), dose to organs at risk (OARs), secondary cancer complication probability (SCCP), and excess absolute risk (EAR) were used to evaluate the plans. Compared to IMRT, the VMAT and HT plans resulted in higher PTV coverage and homogeneity. The VMAT and HT plans also delivered a lower mean dose to the ipsilateral lung (9.19 ± 1.36 Gy, 9.48 ± 1.17 Gy vs. 11.31 ± 1.42 Gy) and heart (3.99 ± 0.86 Gy, 4.48 ± 0.62 Gy vs. 5.53 ± 1.02 Gy) and reduced the V5Gy, V10Gy, V20Gy, V30Gy, and V40Gy of the ipsilateral lung and heart. The SCCP and EAR for the ipsilateral lung were reduced by 3.67%, 3.09% in VMAT, and 22.18%, 19.21% in HT, respectively. While were increased for the contralateral lung and breast. This study showed that VMAT plans provide a more homogeneous dose distribution to the PTV, minimizing exposure to ipsilateral structures and significantly reducing SCCP and EAR, and slightly increasing dose to contralateral structures. Overall, the VMAT plan can be considered a beneficial technique for BCS patients whose PTV includes the whole breast and regional nodes.

Late hepatic toxicity after breast cancer intensity-modulated radiotherapy using helicoidal tomotherapy

PURPOSE

Helical tomotherapy (HT) is a rotational intensity-modulated radiation therapy (IMRT) technique that allows target conformal irradiation and efficient organs at risk (OAR) sparing in the case of complex target volumes and specific anatomic considerations, but increases the "low-dose bath" to non-target volumes. The aim of this study was to analyze the delayed hepatotoxicity after rotational IMRT (HT) radiation therapy for non-metastatic breast cancer.

PATIENTS AND METHODS

This single-center retrospective study included all non-metastatic breast cancer patients with a normal pre-radiotherapy biological hepatic function who were treated with tomotherapy between January 2010 and January 2021 and for whom the dosimetric parameters for the whole liver were assessable. A logistic regression analysis was employed. The selected covariates for the multivariate analysis were those with a P-value that was less or equal to 0.20 in the univariate analysis.

RESULTS

Forty-nine patients were included in this study: 11 patients (22%) received Trastuzumab for 1 year in tumors with an HER2-expression; 27 patients (55%) received radiation therapy for cancer of the right or bilateral breasts; 43 patients (88%) received lymph node irradiation and 41 patients (84%) received a tumor bed boost. Mean and maximum doses to the liver were 2.8Gy [0.3-16.6] and 26.9Gy [0.7-51.7], respectively. With a median follow-up after irradiation was 5.4 years (range, 6 to 115 months), 11 patients (22%) had developed delayed low grade biological hepatic abnormalities: all patients had grade 1 delayed hepatotoxicity; 3 patients (6%) had additional grade 2 delayed hepatotoxicity. There was no hepatotoxicity at grade 3 or higher. According to the univariate and multivariate analysis, Trastuzumab was a significant predictive variable of late biological hepatotoxicity (OR=4.4 [1.01-20.18], P=0.04). No other variable was statistically associated with delayed biological hepatotoxicity.

CONCLUSION

Delayed hepatotoxicity after multimodal non-metastatic breast cancer management including rotational IMRT was negligible. Consequently, the liver doesn't have to be considered like an organ-at-risk in the analysis of breast cancer radiotherapy but future prospectives studies are needed to confirm these findings.

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.

Radiation Exposure of Cardiac Conduction Nodes During Breast Proton Therapy

Purpose

The exposition of cardiac conduction system during breast radiation therapy has never been studied, despite the increasing use of intensity-modulated radiation therapy, which exposes larger volume to low-dose bath. We evaluated conduction node exposure during breast irradiation with volumetric modulated arc therapy and estimated the potential dosimetric benefit with intensity-modulated proton therapy.

Materials and Methods

Atrioventricular (AVN) and sinoatrial (SAN) nodes were retrospectively delineated according to published guidelines on the simulation computed tomography scans of 12 breast cancer patients having undergone conserving surgery and adjuvant locoregional volumetric modulated arc therapy. Intensity-modulated proton therapy treatment was replanned on the simulation computed tomography scans for all breast cancer patients. Mean and maximum doses delivered to the SAN and the AVN were retrieved and compared. Correlation coefficients were calculated between doses to the SAN or the AVN and the whole heart.

Results

Average mean doses delivered to the SAN and AVN were 2.8 and 2.3 Gy, respectively, for left-sided irradiation and 9.6 and 3.6 Gy, respectively, for right-sided irradiation. Average maximum doses to the SAN and AVN were 3.5 Gy and 2.8 Gy, respectively, for left-sided irradiation and 13.1 and 4.6 Gy, respectively, for right-sided irradiation. Intensity-modulated proton therapy significantly reduced mean and maximum doses to the SAN and AVN. Correlations between doses to the SAN or AVN and whole heart were usually significant.

Conclusion

SAN and AVN can be substantially exposed during breast volumetric modulated arc therapy, especially for right-sided irradiation. Cardiotoxicity studies evaluating conduction node exposure might define dose constraints and criteria for additional cardiac-sparing techniques, such as respiratory techniques or proton therapy, which could benefit patients with underlying rhythmic or conduction disorders.

Dosimetric evaluation of the benefit of deep inspiration breath hold (DIBH) for locoregional irradiation of right breast cancer with volumetric modulated arctherapy (VMAT)

INTRODUCTION

Right-lateralized cardiac substructures can be substantially exposed during right breast cancer (R-BC) radiotherapy. The cardiac benefit of deep inspiration breath hold (DIBH) is established in combination with volumetric modulated arctherapy (VMAT) for left breast cancer with regional node irradiation but is unknown for R-BC. This study evaluated the dosimetric benefit of DIBH for locoregional irradiation of R-BC with VMAT.

MATERIAL AND METHODS

All patients treated for R-BC with adjuvant locoregional DIBH-VMAT in the Department of Radiation Oncology of the Institut Curie (Paris, France) until December 2022 were included, corresponding to 15 patients. FB- and DIBH-VMAT plans were compared both for a normofractionated regimen (50 Gy/25fx) used for treatment and a replanned hypofractionated regimen (40 Gy/15fx). Dose to the heart, cardiac substructures (sinoatrial node (SAN), atrio-ventricular node (AVN), right coronary artery, left anterior descending coronary artery, left ventricle), ipsilateral lung and liver were retrieved and compared.

RESULTS

Mean heart dose (MHD) was 3.33 Gy with FB vs. 3.10 Gy with DIBH on normofractionated plans (p = 0.489), and 2.58 Gy with FB vs. 2.41 Gy with DIBH on hypofractionated plan (p = 0.489). The benefit of DIBH was not significant for any cardiac substructure. The most exposed cardiac substructure were the SAN (mean dose of 6.62 Gy for FB- and 5.64 Gy for DIBH-VMAT on normofractionated plans) and the RCA (mean dose of 4.21 Gy for FB- and 4.06 Gy for DIBH-VMAT on normofractionated plans). The maximum benefit was observed for the RCA with a median individual dose reduction of 0.84 Gy on normofractionated plans (p = 0.599). No significant dosimetric difference were observed for right lung. Liver mean dose was significantly lower with DIBH with median values decreasing from 2.54 Gy to 0.87 Gy (p = 0.01).

CONCLUSION

Adding DIBH to efficient cardiac-sparing radiotherapy techniques, such as VMAT, is not justified in the general case for locoregional R-BC irradiation. Specific R-BC patient subpopulations who could benefit from additional DIBH combination with locoregional VMAT are yet to be identified.

Helical tomotherapy experience in breast cancer adjuvant radiotherapy and acute toxicity results

Background

This study aimed to evaluate acute toxicity and oncological outcomes of breast cancer patients who underwent adjuvant radiotherapy (RT) with tomotherapy.

Materials and methods

The results of 114 patients who underwent adjuvant RT with Tomotherapy device between 17.08.10-12.06.2021 in Ankara Atatürk Training and Research Hospital and Ankara City Hospital were evaluated retrospectively. The primary endpoint of the study was acute adverse events, and the secondary endpoints were overall survival (OS) and disease-free survival (DFS).

Results

The results of 103 patients who met the inclusion criteria were analyzed. The median follow-up was 21 (range 1-125.8) months. Grade +3 esophagitis was not observed in any patient; no esophagitis was observed in 60 (58.3%) patients. Grade 3 dermatitis was observed in 3 (2.9%) patients. In addition, dermatitis was not observed in 47 (45.6%) patients. The relationship between chest wall volume and esophagitis development was statistically significant (p = 0.006; Z score: -2769). The median OS was 24.1 (range 1-128.5) and median disease-free survival was 21.1 (range 1-125.8) months. Five patients (4.9%) died and 9 patients (8.7%) relapsed. Local recurrence was observed in only 1 (1%) patient. There was a statistically significant correlation between OS and contralateral lung V20 dose [p < 0.001; Spearman Correlation Coefficient (SCC) -406) and heart mean dose (p < 0.001; SCC -370)]. There was a statically significant correlation between DFS and cN (p < 0.001); pN (p < 0.001); heart mean dose (p < 0.001; SCC -351); contralateral lung V5 dose (p = 0.041; SCC -213); contralateral lung V20 dose (p < 0.001; SCC -434).

Conclusion

Acute toxicity results show improvement in breast cancer adjuvant radiotherapy with helical tomotherapy.

Dosimetric evaluation of VMAT and helical tomotherapy techniques comparing conventional volumes with clinical target volumes based on new ESTRO ACROP post-mastectomy with immediate implant reconstruction contouring guidelines

Background

The ESTRO-ACROP Consensus Guideline (EACG) recommends implant excluded clinical target volume (CTVp) definitions for post-mastectomy radiation therapy after implant-based immediate breast reconstruction (IBR). The purpose of this study is to investigate the effectiveness of Helical Tomotherapy (HTp) and Volumetric Modulated Arc Therapy (VMATp) treatment techniques in terms of CTVp coverage and reduced organ at risk (OAR), normal tissue and implant doses when CTVp was used for treatment planning as the target structure instead of conventional CTV.

Methods

Eight left-sided and eight right-sided breast cancer patients who underwent IBR after mastectomy were included in this study. Planning CT data sets were acquired during free breathing and patients were treated with HT technique targeted to conventional CTV. Retrospectively, CTVp was delineated based on EACG by the same radiation oncologist, and treatment plans with HTp and VMATp techniques were generated based on CTVp. For each patient, relevant dosimetric parameters were obtained from three different treatment plans.

Results

There was no statistically significant difference on target coverage in terms of, PTVp-D95, PTVp-Vpres, homogeneity index (p > 0.05) between HTp and VMATp plans. But, the conformity numbers were significantly higher (HTp vs VMATp, 0.69 ± 0.15 vs 0.79 ± 0.12) for VMATp (Z = − 2.17, p = 0.030). While HTp significantly lowered Dmax and Dmean for LAD (LAD-D_max: χ² = 12.25, p = 0.002 and LAD-D_mean: χ² = 12.30, p = 0.002), neither HTp nor VMATp could reduce maximum and mean dose to heart (p > 0.05). Furthermore, heart volume receiving 5 Gy was significantly higher for VMATp when compared to HTp (21.2 ± 9.8 vs 42.7 ± 24.8, p: 0.004). Both techniques succeeded in reducing the mean dose to implant (HTp vs HT, p < 0.001; VMATp vs HT, p < 0.001; VMATp vs HTp, p = 0.005).

Conclusion

Both HTp and VMATp techniques succeeded to obtain conformal and homogeneous dose distributions within CTVp while reducing the mean implant dose. HTp was found to be superior to VMATp with regards to lowering all OAR doses except for CB.

Cardiac Function after Modern Radiation Therapy with Volumetric Modulated Arc Therapy or Helical Tomotherapy for Advanced Left-Breast Cancer Receiving Regional Nodal Irradiation

Background: Protecting cardiac function in patients with advanced left-breast cancer receiving radiation therapy (RT) with regional nodal irradiation (RNI) is an important issue. Modern RT techniques can limit cardiac exposure. The aim of this study was to explore the association be-tween cardiac dose and cardiac function. Methods: Between 2017 and 2020, we retrospectively reviewed left-breast cancer patients who received adjuvant RT, including RNI with either volumetric-modulated arc therapy (VMAT) or helical tomotherapy (HT). Left ventricular ejection fraction (LVEF) was assessed by echocardiography before RT and 1 year after RT to detect any early deterioration in cardiac systolic function. Results: A total of 30 eligible patients were enrolled. The median follow-up time from the initiation of RT was 3.9 years (range 0.6–5 years). Seventeen patients received VMAT, and the other 13 patients received HT. The median RT dose was 55 Gray (Gy), and the mean heart dose was 3.73 Gy (range 1.95–9.36 Gy). The median LVEF before and after RT was 68% and 68.5%, respectively. No obvious deterioration was found. There was no association between cardiac dose (mean heart dose, V5–V30) and LVEF (change in values or post-RT). Conclusions: For left-breast cancer patients undergoing RT with RNI, VMAT, or HT can be used to limit cardiac exposure. Cardiac function as evaluated by LVEF revealed no obvious deterioration after RT in our patients, and no association was found between cardiac dose and LVEF in those treated with either VMAT or HT in early cardiac surveillance.

Can we treat with radiation breast cancer patients with covid-19 infection? Results from a prospective study

Purpose

The coronavirus disease 2019 (covid-19) caused by the severe acute respiratory syndrome coronavirus 2 (Sars-Cov-2) is at the origin of a global pandemic. This pandemic has prompted the current health system to reorganize and rethink the care offered by health establishments. We report the early and late toxicity in patients infected with covid-19 treated at the same time for early-stage breast cancer.

Material and methods

This is a monocentric prospective study of patients treated in our hospital between March and June 2020 who were diagnosed with covid-19 infection. The inclusion criteria were to be irradiated for early-stage breast cancer and to have a positive covid diagnosis on a polymerase chain reaction (PCR) test and/or a lung computed tomography (CT) scan and/or suggestive clinical symptoms. All of them needed 6 months follow-up clinic after the end of the radiotherapy with clinical examination, mammogram, as well as CT scan to evaluate the lung status. Radiotherapy consisted of breast or chest wall irradiation with or without lymph node irradiation, with protocols adapted to pandemic situation. The treatment-related toxicity was graded according to the Common Toxicology Criteria for Adverse Events (version 4.03).

Results

All 350 patients treated for early-stage breast cancer were studied. Of them, 16 presented clinical symptoms of covid-19 infection, and of them 12 had clinical, CT scan and PCR confirmation. This entire cohort of 12 patients with median age of 56 years (range: 42–72 years) underwent their radiotherapy. During the radiotherapy, nine patients presented radiodermatitis: eight grade 1 (66%) and one grade 2 (8%). Two patients with lymph nodes irradiation presented grade 2 oesophagitis. Late toxicity was evaluated 6 months after the end of the radiotherapy, and there was no radiation or covid lung sequel on the CT scans. One patient presented covid-related dyspnoea, and two had fibrosis.

Conclusion

The half-year follow-up of prospective covid-19 cohort, treated for early-stage breast cancer demonstrated an acceptable toxicity profile with few low-grade adverse events. It seems that the covid-19 infection does not appear to increase the side effects of radiotherapy. Therefore radiotherapy should not be delayed.

Do We Need to Delineate the Humeral Head in Breast Cancer Patients?

Humeral heads can be unintentionally exposed during breast radiotherapy, particularly when regional lymph nodes are targeted. Moreover, rotational intensity-modulated radiation therapy techniques, such as helical tomotherapy (HT), increase the low-dose bath, the consequences of which are subject to debate. The aim of this study was to analyze late adverse events involving humeral heads occurring after adjuvant locoregional breast radiotherapy with HT. This single-center retrospective study included 159 breast cancer patients locoregionally irradiated, including the regional lymph nodes, in an adjuvant setting with HT at Institut Curie (Paris, France), between January 2010 and 2016. After a median delay of 48 months, six patients (3.8%) developed localized bone pain, three (1.9%) developed a shoulder functional limitation and one (0.6%) developed a traumatic humeral head fracture. The average mean and maximum doses to humeral heads were 9.18 Gy and 24.41 Gy, respectively, and were not statistically associated with humeral head adverse events. Adverse events were statistically more frequent after mastectomy than after breast-conserving surgery. Berg's level 1 and 2/3 irradiation, and right-sided radiotherapy were associated with an increased maximum dose. In summary, clinical adverse events were rare, and radiation exposure to humeral heads was low. No correlation was found between dosimetric parameters and late toxicity.

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.

Radiodermatitis and Fibrosis in the Context of Breast Radiation Therapy: A Critical Review

Simple Summary

Skin toxicity is the main complication during irradiation in the management of early-stage breast cancer. In some cases, it may cause treatment to stop. These toxicities may be acute (mainly radiodermatitis) and/or late (mainly fibrosis). Their understandings, their mechanisms of occurrence, as well as their management is indispensable in order to improve the management of these patients. Through this study we propose to provide a clear picture of these toxicities in relation to the modalities of radiotherapy, advances in their quantification, and management to help practitioners improve their knowledge and clinical practices on this topic.

Abstract

Background: Radiation therapy has been progressively improved in order to maintain a satisfactory tumour response, while reducing toxicity. We will review the incidence of radiodermatitis and fibrosis according to the various radiation and fractionation techniques. We will then focus on the various methods used to manage, prevent, and quantify this toxicity. Method: More than 1753 articles were identified using the various search terms. We selected 53 articles to answer the questions addressed in this study according to criteria set in advance. Result: The literature reports lower acute toxicity with IMRT compared to 3DCRT, but no significant differences in terms of late toxicities. Partial breast irradiation appears to be less effective in terms of local control with a higher rate of late toxicity. Intra operative radiation therapy appears to provide good results in terms of both local control and late toxicity. The hypofractionation has equivalent efficacy and safety to the normofractionated regimen, but with lower rates of radiodermatitis and fibrosis. The adddition of a boost, particularly a sequential boost, increases the risk of fibrosis and radiodermatitis during treatment. Conclusion: The development of IMRT has significantly reduced acute toxicity and has improved tolerability during treatment. Modified fractionation has reduced treatment time, as well as adverse effects.

Comparison of sliding window and field-in-field techniques for tangential whole breast irradiation using the Halcyon and Synergy Agility systems

BACKGROUND

To implement a tangential treatment technique for whole breast irradiation using the Varian Halcyon and to compare it with Elekta Synergy Agility plans.

METHODS

For 20 patients two comparable treatment plans with respect to dose coverage and normal tissue sparing were generated. Tangential field-in-field treatment plans (Pinnacle/Synergy) were replanned using the sliding window technique (Eclipse/Halcyon). Plan specific QA was performed using the portal Dosimetry and the ArcCHECK phantom. Imaging and treatment dose were evaluated for treatment delivery on both systems using a modified CIRS Phantom.

RESULTS

The mean number of monitor units for a fraction dose of 2.67 Gy was 515 MUs and 260 MUs for Halcyon and Synergy Agility plans, respectively. The homogeneity index and dose coverage were similar for both treatment units. The plan specific QA showed good agreement between measured and calculated plans. All Halcyon plans passed portal dosimetry QA (3%/2 mm) with 100% points passing and ArcCheck QA (3%/2 mm) with 99.5%. Measurement of the cumulated treatment and imaging dose with the CIRS phantom resulted in lower dose to the contralateral breast for the Halcyon plans.

CONCLUSIONS

For the Varian Halcyon a plan quality similar to the Elekta Synergy device was achieved. For the Halcyon plans the dose contribution from the treatment fields to the contralateral breast was even lower due to less interleaf transmission of the Halcyon MLC and a lower contribution of scattered dose from the collimator system.

Breast cancer treatment-related cardiovascular disturbances: advocacy for a watchful attitude in this never-ending story

INTRODUCTION

Thanks to the emergence of new therapeutics, prognosis and outcome of breast cancer patients (any subtype) have improved significantly. This raises the issue of the interactions and side effects related to the use of multiple drugs. Thus, to decide on a treatment, the optimal benefit risk-ratio should be carefully watched as toxicities such as cardiac ones effect on long-term survival. Indeed, nowadays in France, cardiovascular diseases rank first as causes of death in women.

AREAS COVERED

This non-exhaustive review aims to report the currently available data on cardiac side effects caused by the use of emerging drugs in breast cancer, in localized or metastatic diseases alike. We will focus on HER2-inhibitors, cyclin-dependent-kinase 4/6 and PARP inhibitors, chemotherapy and immunotherapy, before discussing the means of prevention.

EXPERT OPINION

Although this issue has largely been studied, the recent emergence of new drugs emphasizes the necessity for oncologists to adapt their practice to a multidisciplinary model that includes cardio-oncology.

Modern Rotational Radiation Techniques with Volumetric Modulated Arc Therapy or Helical Tomotherapy for Optimal Sparing of the Lung and Heart in Left-Breast Cancer Radiotherapy Plus Regional Nodal Irradiation: A Comparative Dosimetric Analysis

Simple Summary

For advanced left-breast cancer patients, adjuvant radiotherapy (RT) with regional nodal irradiation (RNI) has been indicated to reduce cancer recurrence and mortality. Modern arc RT techniques, volumetric-modulated arc therapy (VMAT), or helical tomotherapy (HT), can minimize normal organ exposure without compromising disease control. The aim of this study is to identify which arc technique is optimal for patients receiving left-breast RT with RNI, and to explore distinct RNI volumes with or without IMN. A total of 108 eligible patients were enrolled (70 VMAT, 38 HT). VMAT reduced the mean dose and low-dose exposure to the heart, ipsilateral lung, whole lung, contralateral breast, and esophagus compared with HT. The advantage of VMAT for normal organ sparing was distinct when performing RNI with IMN irradiation. To limit normal organ exposure and reduce potential toxicities, VMAT is the optimal technique for patients with left-breast cancer who are undergoing RT with RNI.

Abstract

Background: For advanced breast cancer with lymph node involvement, adjuvant radiotherapy (RT) with regional nodal irradiation (RNI) has been indicated to reduce cancer recurrence and mortality. However, an extensive RT volume is associated with normal organ exposure, which increases the toxicity and affects patient outcomes. Modern arc RT techniques can improve normal organ sparing compared with conventional techniques. The aim of this study was to explore the optimal technique for left-breast RT with RNI. Methods: We retrospectively reviewed patients receiving RT with RNI for left-breast cancer. We used modern arc RT techniques with either volumetric-modulated arc therapy (VMAT) or helical tomotherapy (HT) with a novel block technique, and compared differences in dosimetry parameters between the two groups. Subgroup analysis of RNI with or without internal mammary node (IMN) volume was also performed. Results: A total of 108 eligible patients were enrolled between 2017 and 2020, of whom 70 received VMAT and 38 received HT. The median RT dose was 55 Gy. No significant differences were found regarding the surgery, RT dose, number of fractions, target volume, and RNI volume between the VMAT and HT groups. VMAT reduced the heart mean dose more than HT (3.82 vs. 5.13 Gy, p < 0.001), as well as the cardiac parameters of V5–V20, whole-lung mean dose, lung parameters of V5–V20, and contralateral-breast and esophagus mean dose. In the subgroup analysis of RNI with IMNs, the advantage of VMAT persisted in protecting the heart, lung, contralateral breast, and esophagus. HT was beneficial for lowering the thyroid mean dose. For RNI without IMN, VMAT improved the low-dose exposure of the heart and lung, but HT was similar to VMAT in terms of heart, whole-lung, and contralateral-breast mean dose. Conclusions: For patients with left-breast cancer receiving adjuvant RT with RNI, VMAT reduced the exposure dose to the heart, lung, contralateral breast, and esophagus compared with HT. VMAT was superior to HT in terms of normal organ sparing in the patients who underwent RNI with IMN irradiation. Considering the reduction in normal organ exposure and potential toxicity, VMAT is the optimal technique for patients receiving RNI when deep inspiration breath-hold is not available.

Comparing TomoHelical and TomoDirect in postmastectomy hypofractionated radiotherapy after immediate breast reconstruction

BACKGROUND

Postmastectomy radiotherapy (PMRT) with TomoHelical™ (TH) or TomoDirect™ (TD) allows a uniform target coverage. In this study, we compare treatment plans using TD and TH in the setting of hypofractionated PMRT and immediate breast reconstruction.

MATERIAL AND METHODS

The TD-treatment plans of breast cancer patients treated between May 2016 and August 2019 were retrospectively selected. All the TD plans were re-planned on TH with the same prescription dose (40.05 Gy/15 fractions) and according to our dose/volume constraints. Data about the 2 treatment plans were compared with a focus on PTV coverage and all the organs at risk (OARs) constraints.

RESULTS

Fifty patients for a total number of 100 treatment plans (50 with TD and 50 re-planned with TH) were analyzed. All the median value in the TD PTV CHEST WALL plans fulfilled the predefined planning objectives, even though TH emerged as best for target coverage with statistically significant difference for V90%. TD provided the lowest V95% for the PTV SVC, but the median value was near to the recommended value of 90% (89.8 % vs 98.6% for TD and TH, respectively). Overall, TD reached the best OARs sparing. The main statistically significant differences with TH were for contralateral breast, ipsilateral and contralateral lung. All the other dose values for TH were higher than TD, but they fulfilled the recommended/acceptable predefined planning objectives.

CONCLUSIONS

In the setting of PMRT, TD compared to TH reached an acceptable target volume coverage, with an optimal sparing of OARs.

Cardiac substructure exposure in breast radiotherapy: a comparison between intensity modulated proton therapy and volumetric modulated arc therapy

INTRODUCTION

Proton therapy for breast cancer treatment reduces cardiac radiation exposure. Left-sided breast cancer patients with indication for internal mammary chain (IMC) irradiation are most at risk of radiation-induced cardiotoxicity. This study aims to evaluate in this situation the potential dosimetric benefit of intensity modulated proton therapy (IMPT) over volumetric modulated arc therapy (VMAT) at the cardiac substructure level.

MATERIALS AND METHODS

Cardiac substructures were retrospectively delineated according to ESTRO guidelines on the simulation CT scans of fourteen left-sided breast cancer patients having undergone conserving surgery and adjuvant locoregional free-breathing (FB-) or deep inspiration breath-hold (DIBH-) VMAT with internal mammary chain irradiation. IMPT treatment was re-planned on the simulation CT scans. Mean doses to cardiac substructures were retrieved and compared between VMAT treatment plans and IMPT simulation plans. Pearson correlation coefficients were calculated between mean doses delivered to cardiac substructures using these two techniques.

RESULTS

Mean doses to all cardiac substructures were significantly lower with IMPT than with VMAT. Regardless of the irradiation technique, the most exposed cardiac substructure was the mid segment of the left anterior descending coronary artery (LADCA). Pearson correlation coefficients between mean doses to cardiac substructures were usually weak and statistically non-significant for IMPT; mean heart dose (MHD) only correlated with mean doses delivered to the right ventricle, to the mid segment of the right coronary artery (RCA) and, to a lesser extent, to the LADCA.

CONCLUSION

The dosimetric benefit of IMPT over conformal photon therapy was consistently observed for all cardiac substructures. MHD may not be a reliable dosimetric parameter for precise cardiac exposure evaluation when planning IMPT.

Assessment of a conventional volumetric-modulated arc therapy knowledge-based planning model applied to the new Halcyon© O-ring linac in locoregional breast cancer radiotherapy

INTRODUCTION

The aim of this study was to evaluate the performance of a knowledge-based planning (KBP) model for breast cancer trained on plans performed on a conventional linac with 6 MV FF (flattening filter) beams and volumetric-modulated arc therapy (VMAT) for plans performed on the new jawless Halcyon© system with 6 MV FFF (flattening filter-free) beams.

MATERIALS AND METHODS

Based on the RapidPlan© (RP) KBP optimization engine, a DVH Estimation Model was first trained using 56 VMAT left-sided breast cancer treatment plans performed on a conventional linac, and validated on another 20 similar cases (without manual intervention). To determine the capacity of the model for Halcyon©, an additional cohort of 20 left-sided breast cancer plans was generated with RP and analyzed for both TrueBeam© and Halcyon© machines. Plan qualities between manual vs RP (followed by manual intervention) Halcyon© plans set were compared qualitatively by blinded review by radiation oncologists for 10 new independent plans.

RESULTS

Halcyon© plans generated with the VMAT model trained with conventional linac plans showed comparable target dose distribution compared to TrueBeam© plans. Organ sparingwas comparable between the 2 devices with a slight decrease in heart dose for Halcyon© plans. Nine out of ten automatically generated Halcyon© plans were preferentially chosen by the radiation oncologists over the manually generated Halcyon© plans.

CONCLUSION

A VMAT KBP model driven by plans performed on a conventional linac with 6 MV FF beams provides high quality plans performed with 6 MV FFF beams on the new Halcyon© linac.

Clinical practice of breast cancer protontherapy: A single-centre experience from selection to treatment

PURPOSE

Breast protontherapy efficiently limits cardiac, lung and contralateral breast exposure, which may clinically translate into better late tolerance profile compared with classic photon techniques. While breast protontherapy is already implemented in the United States and in some European countries, clinical experience of breast cancer protontherapy is currently limited in France. The aim of this study is to evaluate the clinical practice of breast cancer protontherapy at the Institut Curie in order to implement this technique at a larger scale.

MATERIALS AND METHODS

Data from all breast cancer patients that have been addressed to the protontherapy centre of Orsay (CPO, Institut Curie) for adjuvant breast protontherapy were retrieved. We analysed why these patients were ultimately treated with protontherapy or not.

RESULTS

Between November 2019 and November 2020, eleven breast cancer patients have been evaluated for adjuvant protontherapy at the CPO. Two of them were ultimately treated with proton beams; adjuvant breast protontherapy therapy was well tolerated. The nine other patients were not treated with protontherapy due to lack of availability of protontherapy treatment rooms in acceptable time limits, at the time of patient evaluation.

CONCLUSION

Despite dosimetric advantages and excellent clinical tolerance, lack of availability of protontherapy machines currently limits wider implementation of breast protontherapy.

Volume-based algorithm of lung dose optimization in novel dynamic arc radiotherapy for esophageal cancer

This study aims to develop a volume-based algorithm (VBA) that can rapidly optimize rotating gantry arc angles and predict the lung V₅ preceding the treatment planning. This phantom study was performed in the dynamic arc therapy planning systems for an esophageal cancer model. The angle of rotation of the gantry around the isocenter as defined as arc angle (θ_A), ranging from 360° to 80° with an interval of 20°, resulting in 15 different θ_A of treatment plans. The corresponding predicted lung V₅ was calculated by the VBA, the mean lung dose, lung V₅, lung V₂₀, mean heart dose, heart V₃₀, the spinal cord maximum dose and conformity index were assessed from dose-volume histogram in the treatment plan. Correlations between the predicted lung V₅ and the dosimetric indices were evaluated using Pearson's correlation coefficient. The results showed that the predicted lung V₅ and the lung V₅ in the treatment plan were positively correlated (r = 0.996, p < 0.001). As the θ_A decreased, lung V₅, lung V₂₀, and the mean lung dose decreased while the mean heart dose, V₃₀ and the spinal cord maximum dose increased. The V₂₀ and the mean lung dose also showed high correlations with the predicted lung V₅ (r = 0.974, 0.999, p < 0.001). This study successfully developed an efficient VBA to rapidly calculate the θ_A to predict the lung V₅ and reduce the lung dose, with potentials to improve the current clinical practice of dynamic arc radiotherapy.

The impact of variable relative biological effectiveness in proton therapy for left-sided breast cancer when estimating normal tissue complications in the heart and lung

The aim of this study was to evaluate the clinical impact of relative biological effectiveness (RBE) variations in proton beam scanning treatment (PBS) for left-sided breast cancer versus the assumption of a fixed RBE of 1.1, particularly in the context of comparisons with photon-based three-dimensional conformal radiotherapy (3DCRT) and volumetric modulated arc therapy (VMAT). Ten patients receiving radiation treatment to the whole breast/chest wall and regional lymph nodes were selected for each modality. For PBS, the dose distributions were re-calculated with both a fixed RBE and a variable RBE using an empirical RBE model. Dosimetric indices based on dose-volume histogram analysis were calculated for the entire heart wall, left anterior descending artery (LAD) and left lung. Furthermore, normal tissue toxicity probabilities for different endpoints were evaluated. The results show that applying a variable RBE significantly increases the RBE-weighted dose and consequently the calculated dosimetric indices increases for all organs compared to a fixed RBE. The mean dose to the heart and the maximum dose to the LAD and the left lung are significantly lower for PBS assuming a fixed RBE compared to 3DCRT. However, no statistically significant difference is seen when a variable RBE is applied. For a fixed RBE, lung toxicities are significantly lower compared to 3DCRT but when applying a variable RBE, no statistically significant differences are noted. A disadvantage is seen for VMAT over both PBS and 3DCRT. One-to-one plan comparison on 8 patients between PBS and 3DCRT shows similar results. We conclude that dosimetric analysis for all organs and toxicity estimation for the left lung might be underestimated when applying a fixed RBE for protons. Potential RBE variations should therefore be considered as uncertainty bands in outcome analysis.

Cardiac radiation-induced sarcomas: A SEER population-based study and a literature review

PURPOSE

The aim of this study was to better understand the incidence and the clinical characteristics of cardiac radiation-induced sarcomas (RIS).

MATERIAL AND METHODS

We used the surveillance, epidemiology, and end results (SEER) program cancer registry data, the largest cancer database in the United States in order to identify all cardiac RIS between 1973 and 2015. We relied on the Memorial Sloan-Kettering Cancer Center (MSKCC)-modified 1948 Cahan criterions for RIS identification.

RESULTS

Out of 8,136,951 cancer patients from the SEER database, we identified 448 patients diagnosed with cardiac sarcomas. Of these 448 cardiac sarcoma patients, two were considered to have developed a cardiac RIS: a metastatic rhabdomyosarcoma occurring after one to two years following lung carcinoma irradiation, and a soft tissue sarcoma (of unspecified type) developed six years after radiation therapy for an aggressive left-sided breast carcinoma. Based on this observation, we estimated that cardiac RIS represented about 0.4% (95% CI 0.1%-1.6%) of all cardiac sarcomas. A literature review has been conducted and yielded three additional cases of cardiac RIS.

CONCLUSION

Cardiac RIS are extremely rare malignancies, associated with a very pejorative prognosis. The two reported histologies are angiosarcomas and rhabdomyosarcomas, which might be over-represented among cardiac RIS. A metastatic evolution is possible for cardiac radiation-induced rhabdomyosarcomas. Surgical excision, when feasible, is a therapeutic option and is the only specific treatment reported to this date.

Evaluating cardiac substructure radiation exposure in breast rotational intensity modulated radiation therapy: Effects of cancer laterality, fractionation and deep inspiration breath-hold

PURPOSE

Rotational intensity-modulated radiation therapy currently has a growing role in breast cancer radiation therapy, since this radiation technique reduces cardiac radiation exposure while homogeneously covering target volumes. This study aims to evaluate radiation exposure of cardiac substructures across a broad spectrum of breast cancer cases differing by cancer laterality, fractionation regimen and addition of deep-inspiration breath hold.

MATERIALS AND METHODS

Cardiac substructures were delineated following guidelines endorsed by the European Society for Radiotherapy and Oncology (ESTRO) for forty-four breast cancer patients having undergone conserving surgery and adjuvant rotational intensity-modulated radiation therapy. Target volumes consisted of the whole breast with a boost, axillary and internal mammary nodes. Patients were treated using free-breathing technique for left-sided or right-sided, normofractionated or hypofractionated helical tomotherapy or volumetric modulated arc therapy, or using deep-inspiration breath hold for left-sided normofractionated volumetric modulated arc therapy. Mean and maximum doses to cardiac substructures were retrieved. Correlations were performed between mean- and maximum radiation doses to cardiac substructures.

RESULTS

Left-sided and right-sided irradiations were associated with different cardiac substructure exposure patterns despite comparable mean heart dose: 7.21Gy for left-sided normofractionated regimen, 6.28Gy for right-sided normofractionated regimen. Deep-inspiration breath hold reduced mean doses to almost all cardiac substructures for left-sided irradiation, but did not decrease maximum doses to coronary arteries. Correlations between mean- and maximum doses to cardiac substructures were usually moderate, but stronger for right-sided irradiation.

CONCLUSION

Despite comparable mean heart dose, cardiac substructure radiation exposure patterns with rotational intensity-modulated radiation therapy strongly depend on the breast side, which could trigger clinically different long-term cardiotoxicity events. Deep-inspiration breath hold improves cardiac substructure dosimetry. Mean- and maximum heart dose could probably not be used as surrogate markers for precise cardiac substructure evaluation. In a near future, clinical practice and cardiotoxicity studies could possibly gain by considering cardiac substructure in a more systematic manner, possibly relying on cardiac autosegmentation algorithms.

Evaluation of a delineation software for cardiac atlas-based autosegmentation: An example of the use of artificial intelligence in modern radiotherapy

PURPOSE

The primary objective of this work was to implement and evaluate a cardiac atlas-based autosegmentation technique based on the "Workflow Box" software (Mirada Medical, Oxford UK), in order to delineate cardiac substructures according to European Society of Therapeutic Radiation Oncology (ESTRO) guidelines; review and comparison with other cardiac atlas-based autosegmentation algorithms published to date.

MATERIALS AND METHODS

Of an atlas of data set from 20 breast cancer patients' CT scans with recontoured cardiac substructures creation according to the ESTRO guidelines. Performance evaluation on a validation data set consisting of 20 others CT scans acquired in the same treatment position: cardiac substructure were automatically contoured by the Mirada system, using the implemented cardiac atlas, and simultaneously manually contoured by a radiation oncologist. The Dice similarity coefficient was used to evaluate the concordance level between the manual and the automatic segmentations.

RESULTS

Dice similarity coefficient value was 0.95 for the whole heart and 0.80 for the four cardiac chambers. Average Dice similarity coefficient value for the left ventricle walls was 0.50, ranging between 0.34 for the apical wall and 0.70 for the lateral wall. Compared to manual contours, autosegmented substructure volumes were significantly smaller, with the exception of the left ventricle. Coronary artery segmentation was unsuccessful. Performances were overall similar to other published cardiac atlas-based autosegmentation algorithms.

CONCLUSION

The evaluated cardiac atlas-based autosegmentation technique, using the Mirada software, demonstrated acceptable performance for cardiac cavities delineation. However, algorithm improvement is still needed in order to develop efficient and trusted cardiac autosegmentation working tools for daily practice.

Dosimetric comparison of volumetric-modulated arc therapy and helical tomotherapy for adjuvant treatment of bilateral breast cancer

Purpose:

Dosimetric comparison between volumetric-modulated arc therapy (VMAT) and helical tomotherapy (HT) in the treatment of bilateral breast cancer (BBC).

Materials and methods:

Ten patients treated on HT were selected retrospectively. Dose prescription was 50 Gy in 25 fractions to breast/chest wall and supraclavicular fossa (SCF) while tumour bed was simultaneously boosted to 61 Gy in 25 fractions. VMAT plans were made with four mono-isocentric partial arcs. The monitoring unit (MU) and treatment time were used to quantify the treatment efficiency. Target volumes were compared for homogeneity index (HI), conformity index (CI) while organs at risk (OARs) were compared for relevant dose volumes and integral doses (IDs).

Result:

For targets, no significant difference is observed between VMAT and HT in CI but VMAT could give better HI. The mean lung dose, V20 and V5 is 10·6 Gy versus 8·4 Gy (p-value 0·03), 12% versus 11·5% (p-value 0·5) and 78·1% versus 43·4% (p-value 0·005), respectively. The mean heart dose, V30 and V5 is 4·9 Gy versus 4·7 Gy (p-value 0·88), 0·5% versus 1·5% (p-value 0·18) and 26·2% versus 22·8% (p-value 0·4). Integral dose (ID) for the whole body and heart are comparable: 289 Gy kg versus 299 Gy kg (p-value 0·24) and 2·9 Gy kg versus 2·8 Gy kg (p-value 0·80). ID for lungs was significantly higher with VMAT: 7·9 Gy kg versus 6·3 Gy kg (p-value 0·03). There is a 53% reduction in treatment time and 78% in MU with VMAT against HT.

Conclusion:

VMAT can generate clinically acceptable plans comparable to HT for BBC. HT shows better control over low dose spillage in lungs compared to VMAT thereby increasing ID to lungs. VMAT shows better homogeneity and efficient treatment delivery than HT.

Cardiotoxicity in breast cancer patients treated with radiation therapy: From evidences to controversies

Radiation therapy has a prime importance for breast cancer management. However, first-generation techniques delivered significant radiation dose to the heart, which substantially increased cardiac mortality. Breast radiation therapy has fortunately evolved, and state-of-the-art radiation therapy techniques currently efficiently spare the heart without altering local control or overall survival. However, at the present time, potential cardiotoxicity risk is still a matter of concern and controversies exist concerning how to precisely evaluate cardiac radiation exposure, how to predict radiation-induced cardiac adverse events and which dosimetric constraints are clinically relevant. Based on current literature, this paper aims to review the present understanding of cardiotoxicity associated with breast cancer irradiation and to discuss controversies and perspectives about cardiac sparing improvement.

Axillary nodal irradiation practice in the sentinel lymph node biopsy era: Comparison of the contemporary available 3D and IMRT techniques

OBJECTIVE

Our study aimed to compare regional node coverage and doses to the organ at risk (OAR) using conventional technique (CT) vs "AMAROS" (AT) vs intensity-modulated radiation therapy (IMRT) techniques in patients receiving regional nodal irradiation (RNI) for breast cancer (BC).

METHODS

We included 30 consecutive patients with BC who received RNI including axillary nodes. Two independent and blinded dosimetric RNI plans were generated for all patients. For target volume coverage, we analyzed the V95%, the D95%, the mean and the minimal dose within the nodal station. For hotspots within nodal target volume, we used the V105%, the V108% and the maximal doses. For OAR, lung V20, mean lung and heart doses, the maximal dose to the brachial plexus and the axillary-lateral thoracic vessel junction region were compared between the three techniques.

RESULTS

Target volume coverage and hotspots: Mean V95% in stations I, II, III and IV were 35.8% and 75% respectively with CV, 22.59 and 59.9% respectively with AT technique and 45.58 and 99.6% respectively with IMRT with statistically significant differences (p < 0.001). Mean V105% (cc) in axillary and supraclavicular stations were 21.3 and 6.4 respectively with CV, 1.2 and 0.02 respectively with AT technique and 0.5 and 0.4 respectively with IMRT with statistically significant differences (p < 0.001)..OARs: The mean ipsilateral lung V20 was 16.9%, 16.4 and 13.3% with CT, AT and IMRT respectively. The mean heart dose (Gy) was 0.3, 0.2 and 0.2 with CT, AT and IMRT respectively. The maximal dose to the plexus brachial (Gy) was 50.3, 46.3 and 47.3 with CT, AT and IMRT respectively. The maximal dose to the axillary-lateral thoracic vessel junction (Gy) was 52.3, 47.3 and 47.6 with CT, AT and IMRT respectively. The differences were statistically significant for all OAR (p < 0.001).

CONCLUSION

AT is a valuable technique for RNI including axilla in patients with limited sentinel lymph node biopsy involvement without additional axillary lymph node dissection since it decreases hotspots in the target volume and lowers the radiation exposure of the OAR. For more advanced tumors or patients who did not respond to primary systemic therapy, CT or IMRT should be considered because of their better coverage of the potentially residual nodal disease. IMRT combines several advantages of offering high conformal plans, limited hotspots and protection of main OAR. The clinical impact of these dosimetric differences need to be addressed.

ADVANCES IN KNOWLEDGE

This study is to our knowledge the first to compare conventional three-dimensional and IMRT techniques for regional nodal irradiation for each nodal station in breast cancer in a context of increasing utilization of axillary irradiation.

Helical tomotherapy: Comparison of Hi-ART and Radixact clinical patient treatments at the Technical University of Munich

The helical tomotherapy (HT) Hi-ART system was installed at our department in April 2007. In July 2018 the first Radixact system in Germany has been launched for clinical use. We present differences, advantages and disadvantages and show future perspectives in patient treatment using two HT devices. We investigate patient characteristics, image quality, radiotherapy treatment specifications and analyze the time effort for treatments with the Hi-ART system from April 2010 until May 2017 and compare it to the data acquired in the first nine months of usage of the Radixact system. Comparing the Hi-ART and Radixact system, the unique option of integrated MVCT image acquisition has experienced distinct improvement in image quality. Time effort for irradiation treatment could be improved resulting in a mean beam on time for craniospinal axis treatment of 636.2 s for the Radixact system compared to 915.9 s for the Hi-ART system. The beneficial use of tomotherapy for complex target volumes is demonstrated by a head and neck tumor case and craniospinal axis treatment. With the Radixact system MVCT image quality has been improved allowing for fast and precise interfraction dose adaptation. The improved time effort for patient treatment could increase the accessibility for clinical usage.

[Individual modification of the dose, volume and fractionation of breast radiotherapy]

Randomized trials demonstrated similar overall survival between mastectomy and breast-conservative surgery followed by adjuvant radiation therapy. Breast-conservative surgery, with adjuvant radiation therapy, with or without neoadjuvant systemic therapy has become the standard of care for women with early or locally advanced breast cancer. Nevertheless, certain cardiac, lung or cutaneous toxicities may alter the long-term body image and the quality of life of a limited number of patients who consider having had "overtreatment" or treatment outside the best knowledge of science. In case of low-risk breast cancer, several trials have evaluated the carcinologic outcome in absence of radiation therapy after breast-conservative surgery. Local recurrences increased in case of breast-conservative surgery alone but without impact on overall survival. Multiple debates have emerged in order to select the most appropriate evaluation criteria. Finally, a large consensus has considered that reducing local recurrences is important but with modern technologies and after identifying patients of individual radiosensitivity. Indeed, in case of a low absolute risk of local recurrence, radiation therapy techniques have been developed to allow a focal treatment especially for patients with high risk of developing late effects. This kind of compromise takes into account the reduction risk of local recurrences but also the probability of developing radiation-induced cutaneous sequelae. In the same way, for patients considered at high risk of recurrence, the huge volumes need specific techniques to better cover the targets while protecting the surrounding critic organs such as heart and lung. Intensity-modulated radiation therapy and the local high boost may help to decrease local recurrences of these more extended and aggressive diseases while considering the individual radiosensitivity that paves the way of long-term sequelae. In this article, we detail a personalized approach of breast radiation therapy considering the absolute risk of local recurrences and the probability of radiation-induced toxicity appearance.

Dosimetric study of the plan quality and dose to organs at risk on tangential breast treatments using the Halcyon linac

Purpose

To investigate the plan quality and doses to the heart, contralateral breast (CB), ipsilateral lung (IL), and contralateral lung (CL) in tangential breast treatments using the Halcyon linac with megavoltage setup fields.

Methods

Radiotherapy treatment plans with tangential beams from 25 breast cancer patients previously treated on a C‐arm linac were replanned for Halcyon. Thirteen corresponded to right‐sided breasts and 12 to left‐sided breasts, all with a dose prescription of 50 Gy in 25 fractions. Plans were created with the following setup imaging techniques: low‐dose (LD) MVCBCT, high‐quality (HQ) MVCBCT, LD‐MV and HQ‐MV pairs and the imaging dose was included in the plans. Plan quality metric values for the lumpectomy cavity, whole‐breast and doses to the organs at risk (OARs) were measured and compared with those from the original plans.

Results

No significant differences in plan quality were observed between the original and Halcyon plans. An increase in the mean dose (Mean) for all the organs was observed for the Halcyon plans. For right‐sided plans, the accumulated Mean over the 25 fractions in the C‐arm plans was 0.4 ± 0.3, 0.2 ± 0.2, 5.4 ± 1.3, and 0.1 ± 0.1 Gy for the heart, CB, IL, and CL, respectively, while values in the MVCBCT‐LD Halcyon plans were 1.2 ± 0.2, 0.6 ± 0.1, 6.5 ± 1.4, and 0.4 ± 0.1 Gy, respectively. For left‐sided treatments, Mean in the original plans was 0.9 ± 0.2, 0.1 ± 0.0, 4.2 ± 1.2, and 0.0 ± 0.0 Gy, while for the MVCBCT‐LD Halcyon plans values were 1.9 ± 0.2, 0.6 ± 0.2, 5.1 ± 1.2, and 0.5 ± 0.2 Gy, respectively.

Conclusions

Plan quality for breast treatments using Halcyon is similar to the quality for a 6 MV, C‐arm plan. For treatments using megavoltage setup fields, the dose contribution to OARs from the imaging fields can be equal or higher than the dose from treatment fields.

Postmastectomy radiation therapy using VMAT technique for breast cancer patients with expander reconstruction

Postmastectomy radiotherapy (PMRT) following immediate breast reconstruction is increasingly adopted in the management of breast cancer patients. We retrospectively evaluate the complication rates of PMRT using VMAT technique to immediate tissue expander-based reconstructions and the possible impact of tissue expander volume on radiotherapy planning. We reviewed the data of patients who underwent immediate expander breast reconstruction and received PMRT with VMAT (50 Gy in 25 fractions) on the reconstructed breast and axillary levels III-IV. Neoadjuvant or adjuvant systemic therapy was administered in most of the patients. Autologous fat grafting was routinely performed at the time of second-stage reconstruction. Between 2015 and 2017, PMRT was delivered to 46 consecutive patients (median age 50 years) with expander reconstruction. Median follow-up was 27 months (range 10-41). Two patients (4.3%) had a reconstruction failure, as expander rupture and infection, following the first- and the second-stage reconstruction, respectively. In most cases expanders were completely inflated before PMRT (65.2%). Median expander volume before PMRT was 425 cm³ (range 150-700 cm³). The amount of expander inflation did not significantly affect dosimetry, except for skin dose, with a surface receiving more than 30 Gy of 36.6 ± 0.9 cm² and 47.0 ± 2.5 cm² for a volume expander below or above the median, respectively. However, this variable was not predictor for complications. Disease progression was recorded in 15.2% of patients. PMRT using VMAT technique for breast cancer patients with expander reconstruction is associated with a very low complication rate. The expander volume before PMRT does not significantly compromise radiotherapy dose distribution.

[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.

Skin toxicity after chest wall/breast plus level III-IV lymph nodes treatment with helical tomotherapy

INTRODUCTION

To evaluate the incidence of toxicity in breast cancer with helical tomotherapy (HT).

MATERIALS AND METHODS

51 patients with breast cancer were assigned to postoperative radiotherapy by means of HT to the chest wall/breast plus draining nodes. During HT treatment, toxicity was monitored and were assessed using the Common Terminology Criteria for Adverse Events 4.0 scale.

RESULTS

Acute skin G3 toxicity observed in 1.9% cases. No acute or late G4 toxicity was observed. At a median follow-up of 21 months 2 patients have late G1 toxicity.

CONCLUSIONS

HT was associated with a low incidence of low-grade skin toxicity.

Safety and benefit of using a virtual bolus during treatment planning for breast cancer treated with arc therapy

Purpose

This study evaluates the benefit of a virtual bolus method for volumetric modulated arc therapy (VMAT) plan optimization to compensate breast modifications that may occur during breast treatment.

Methods

Ten files were replanned with VMAT giving 50 Gy to the breast and 47 Gy to the nodes within 25 fractions. The planning process used a virtual bolus for the first optimization, then the monitors units were reoptimized without bolus, after fixing the segments shapes. Structures and treatment planning were exported on a second scanner (CT) performed during treatment as a consequence to modifications in patient's anatomy. The comparative end‐point was clinical target volume's coverage. The first analysis compared the VMAT plans made using the virtual bolus method (VB‐VMAT) to the plans without using it (NoVB‐VMAT) on the first simulation CT. Then, the same analysis was performed on the second CT. Finally, the level of degradation of target volume coverage between the two CT using VB‐VMAT was compared to results using a standard technique of forward‐planned multisegment technique (Tan‐IMRT).

Results

Using a virtual bolus for VMAT does not degrade dosimetric results on the first CT. No significant result in favor of the NoVB‐VMAT plans was noted. The VB‐VMAT method led to significant better dose distribution on a second CT with modified anatomies compared to NoVB‐VMAT. The clinical target volume's coverage by 95% (V95%) of the prescribed dose was 98.9% [96.1–99.6] on the second CT for VB‐VMAT compared to 92.6% [85.2–97.7] for NoVB‐VMAT (P = 0.0002). The degradation of the target volume coverage for VB‐VMAT is not worse than for Tan‐IMRT: the median differential of V95% between the two CT was 0.9% for VMAT and 0.7% for Tan‐IMRT (P = 1).

Conclusion

This study confirms the safety and benefit of using a virtual bolus during the VMAT planning process to compensate potential breast shape modifications.

The use of helical tomotherapy in the treatment of early stage breast cancer: indications, tolerance, efficacy-a single center experience

PURPOSE

to evaluate our experience in terms of local control, survival, adverse effects in patients treated by adjuvant helical tomotherapy (HT) for breast cancer (BC).

RESULTS

We studied 179 consecutive patients with 194 treated breasts with adjuvant HT. Median follow-up was 38.1 months. Median age was 53 years. Chemotherapy was administered to 83% of patients. All 133 hormone receptor positive tumours received hormonal therapy. As concurrent treatment, apart from trastuzumab monotherapy, 6 patients received systemic therapy concomitant to RT. The HT was generally well tolerated with mostly grade 1 and 2 skin reactions and esophagitis. Only 3% grade III early skin reactions. At last follow-up, there were 2 local recurrences, 1 regional lymph node (LN) recurrence and 6 with metastatic progression. The 5-year progression-free survival was 90.5% (95% CI 84.2-97.3).

MATERIALS AND METHODS

A retrospective study of all patients treated by HT between 2009 and 2015 was done. Patients excluded were those with: breast implants, advanced or metastatic BC, recurrent disease. All patients received breast+/-boost or chest wall irradiation and most received with LN irradiation. Dose constraints for organs at risk were defined using optimization scale developed in our Department. Evaluation of early and late toxicity was done using Common Terminology Adverse Criteria Events v.4.0.

CONCLUSIONS

HT can be used for a well selected group of breast cancer as bilateral tumours, complex anatomy and target volumes where the conventional radiation therapy techniques cannot ensure an optimal dose distribution. Longer follow-up is necessary to confirm and validate these results.

Comparing four radiotherapy techniques for treating the chest wall plus levels III-IV draining nodes after breast reconstruction

OBJECTIVE

To compare the dosimetric outcomes of four radiotherapy (RT) techniques for treating the chest wall plus draining nodes after mastectomy and breast reconstruction.

METHODS

Three-dimensional conformal radiotherapy, linac-based intensity modulated RT, helical tomotherapy (HT) and direct tomotherapy treatments were planned for 40 breast cancer patients. Dose prescription was 50 Gy. Plans were compared in terms of doses to the planning target volume, organs at risk and the homogeneity index. The non-parametric Friedman test for paired data and the Conover post hoc analysis were used for data analysis.

RESULTS

HT provided the highest D90 and D98% and the lowest HI, V107% and D2%. HT was associated with the lowest D2% and V25 Gy to the heart in left-sided treatments but the mean cardiac dose was highest. HT provided the highest V5 Gy and V20 Gy to the ipsilateral lung, but the V30 Gy was lower. The contralateral breast and lung were more exposed with HT.

CONCLUSION

The present dosimetric study together with daily use of CT-MV image guided RT have led us to opt for HT after mastectomy and breast reconstruction and to draw up a suitable protocol for treating the chest wall and levels III and IV draining nodes. Advances in knowledge: HT is a suitable for treating the chest wall and levels III and IV draining nodes.

Critical appraisal of the role of volumetric modulated arc therapy in the radiation therapy management of breast cancer

Background

The aim of this review is the critical appraisal of the current use of volumetric modulated arc therapy for the radiation therapy management of breast cancer. Both clinical and treatment planning studies were investigated.

Material and methods

A Pubmed/MEDLINE search of the National Library of Medicine was performed to identify VMAT and breast related articles. After a first order rejection of the irrelevant findings, the remaining articles were grouped according to two main categories: clinical vs. planning studies and to some sub-categories (pointing to significant technical features). Main areas of application, dosimetric and clinical findings as well as areas of innovations were defined.

Results

A total of 131 articles were identified and of these, 67 passed a first order selection. Six studies reported clinical results while 61 treatment dealed with treatment planning investigations. Among the innovation lines, the use of high intensity photon beams (flattening filter free), altered fractionation schemes (simultaneous integrated boost, accelerated partial breast irradiation, single fraction), prone positioning and modification of standard VMAT (use of dynamic trajectories or hybrid VMAT methods) resulted among the main relevant fields of interest. Approximately 10% of the publications reported upon respiratory gating in conjunction with VMAT.

Conclusions

The role of VMAT in the radiation treatment of breast cancer seems to be consolidated in the in-silico arena while still limited evidence and only one phase II trial appeared in literature from the clinical viewpoint. More clinical reports are needed to fully proove the expected dosimetric benefits demonstrated in the planning investigations.

Proton therapy for locally advanced breast cancer: A systematic review of the literature

BACKGROUND

Radiation therapy plays a major role in the management of adjuvant breast cancer with nodal involvement, with an iatrogenic increase of cardio-vascular risk. Photon therapy, even with intensity modulation, has the downsides of high mean heart dose and heterogeneous target coverage, particularly in the case of internal mammary irradiation. This systematic review of the literature aims to evaluate proton therapy in locally advanced breast cancer.

MATERIAL AND METHODS

PubMed was searched for original full-text articles with the following search terms: «Proton Therapy» and «Breast Cancer». On-going trials were collected using the words "Breast Cancer" and "Protons".

RESULTS

13 articles met the criteria: 6 with passive proton therapy (Double Scattering), 5 with Pencil Beam Scanning (PBS) and 2 with a combination of both. Proton therapy offered a better target coverage than photons, even compared with intensity modulation radiation therapy (including static or rotational IMRT or tomotherapy). With proton therapy, volumes receiving 95% of the dose were around 98%, with low volumes receiving 105% of the dose. Proton therapy often decreased mean heart dose by a factor of 2 or 3, i.e. 1 Gy with proton therapy versus 3 Gy with conventional 3D, and 6 Gy for IMRT. Lungs were better spared with proton therapy than with photon therapy. Cutaneous toxicity observed with double scattering is improved with PBS.

CONCLUSION

Proton therapy reduces mean heart dose in breast cancer irradiation, probably reducing late cardio-vascular toxicity. Large clinical studies will likely confirm a clinical benefit of proton therapy.