Postmastectomy Electron Beam Chest Wall Irradiation in Women With Breast Cancer: A Clinical Step Toward Conformal Electron Therapy

Electron radiation therapy: Back to the future?

Electron radiotherapy has long been preferred to photons for the treatment of superficial lesions because of its physical characteristics (high dose at the surface, rapid decrease in depth). Other characteristics (penumbra, heterogeneity on an oblique or irregular surface) make them difficult to use. In most indications (skin cancers, head and neck, medulloblastoma), with technical progress, in some cases they have been replaced by intensity-modulated conformal radiotherapy, brachytherapy and contact therapy. Other indications (drainage of mesotheliomas or irradiation of benign lesions) have disappeared. The low frequency of use leads to problems of safety and cost-effectiveness. However, modern photon radiotherapy techniques are still less effective than electrons in specific indications such as total skin irradiation (mycosis fungoides) or certain thin chest wall irradiations after total mastectomy, reirradiation or paediatric treatments without protons. Flash therapy, initiated by electrons, has been developed over the last 10 years, providing high-dose irradiation in an extremely short time. Initial results show good efficacy, with fewer side effects than with conventional radiotherapy. These results are leading to clinical technological developments on a larger scale. Although it has been replaced in most indications by more modern techniques, electron radiotherapy remains essential for targeted indications in specialised centres. The emergence of flash therapy will lead to new indications, on machines equipped with this new technology, which have yet to be defined and are currently the responsibility of specialised teams.

Impact of Radiation Therapy Modalities on Loco-regional Control in Inflammatory Breast Cancer

PURPOSE

In inflammatory breast cancer, radiation therapy intensification is considered a standard of care by some teams, although the level of evidence remains low. We sought to analyze the impact of radiation therapy modalities on the risk of loco-regional and distant relapse.

METHODS AND MATERIALS

This retrospective multicenter study included patients with localized inflammatory breast cancer treated between 2010 and 2017. Standard postmastectomy radiation therapy consisted of daily fractions to a total dose of 50 Gy equivalent without a boost or bolus, while intensified radiation therapy referred to the use of a boost or bolus. The cumulative incidence curves of locoregional and distant recurrence were displayed using the competing risk method.

RESULTS

Of the 241 included patients, 165 were treated with standard and 76 with intensified radiation therapy. There was significantly more nodal involvement in the intensified group. With a median follow-up of 40 months postradiation therapy, there was no difference between standard versus intensified radiation therapy regarding the cumulative incidence of locoregional (P = .68) or distant recurrence (P = .29). At 5 years, the risks of locoregional and distant recurrence were 12.1% (95% CI, 7.5; 17.7) and 29.4% (95% CI, 21.8; 37.3) for patients treated with standard radiation therapy and 10.4% (95% CI, 4.4; 19.3) and 21.4% (95% CI, 12.6; 31.9) for those treated with intensified radiation therapy. In multivariate analyses, triple-negative subtype and absence of complete pathologic response were associated with a higher risk of loco-regional recurrence. Radiation therapy intensification had no significant impact on locoregional and distant recurrence. For patients with a non-complete pathologic response (n = 172, 71.7%), no significant differences were observed between the 2 groups for loco-regional (P = .80) and distant (P = .39) recurrence. Severe toxicity rates were similar in both groups.

CONCLUSIONS

Contrary to other important series, this large retrospective multicentric study did not show a locoregional or distant control benefit of intensified radiation therapy. Pooled prospective studies and meta-analyses of intensified radiation therapy are warranted to endorse this approach.

Long-term efficacy and tolerance of a technique for postmastectomy electron beam radiation therapy of the unreconstructed chest wall and lymph node areas for non-metastatic breast cancers

PURPOSE

To evaluate the long-term tolerance and outcome of patients irradiated with an electron beam technique used since 2007 on the chest wall and lymph node areas after mastectomy for non-metastatic locally advanced breast carcinoma.

PATIENTS AND METHODS

All patients irradiated with an improved electron beam technique after mastectomy for non-metastatic breast carcinoma between 2007 and 2011 at Institut Curie (France) were included in this descriptive study. The technique has already been described in other studies, as has its 5-year tolerance and non-inferiority compared to photon irradiation. Acute and chronic toxicity were collected using CTCAE v 3.0. A clinical examination was carried out each week during the radiotherapy and at each 6 months consultation with one mammogram per year at the Institut Curie for at least 5 years. The patients then continued to be followed either at the Institut Curie or in private practice with a good transmission of outpatient consultations, thanks to a system of forms to be completed and integrated into the electronic files. Quantitative and qualitative data are defined by mean and proportion. Statistical comparisons were made by computer using the Chi2 test and Fisher's exact test for categorical variables. Recurrence-free survival was defined as the time between the end of treatment and the date of recurrence or death. Overall survival was defined in the same way without taking into account recurrences. Patients who did not report any events were censored at the date of last news.

RESULTS

Of the 796 patients included, 51.3% had multifocal lesions, 10.1% had triple negative status, and 18.8% displayed overexpression of the Her2 receptor, 196 (24.6%) patients received neoadjuvant chemotherapy and 208 (26.1%) systemic treatment during radiotherapy (chemotherapy or targeted therapy); 514 (64.6%) had at least one positive lymph node. The internal mammary chain (IMC) was irradiated in 85.6% of cases, the supraclavicular areas in 88.3% of cases, the infraclavicular in 77.9% of cases and the axillary area in 14.9% of cases. With a median follow-up of 113 months (range: 2-164 months), locoregional recurrence-free survival and overall 10-year survival was respectively 94.02%, (95% CI: 92.13-98.94) and 79.84% (95% CI: 76.83-82.97). Median survival was not reached. In the long term, 29.6% of patients had telangiectasias (grade 1: 23.3%, grade 2: 5.2%, grade 3: 1.1%). There were 279 patients (35.1%) with secondary breast reconstruction on average 21 months after all treatments. IMC irradiation was not associated with a majority of pulmonary toxicity. Thirty-five patients developed chronic heart disease after radiotherapy, 30 of whom had received anthracyclines and 9 had received traztuzumab. Three of these reported a coronary ischaemic event, including 2 irradiated on the left and 1 on the right, the 4 were irradiated in the vicinity of the IMC and the other lymph node areas, but presented many other cardiovascular risk factors (between 2 and 4). During follow-up, 4.9% of patients had a contralateral recurrence (n=39) and 5.5% had a second non-breast cancer (n=44), of the 6 bronchopulmonary cancers diagnosed, none appeared to be related to chest wall radiotherapy.

CONCLUSION

This study confirms that the improved postmastectomy electron beam radiation therapy technique is well-tolerated after nearly 10 years of follow-up.

Clinical outcomes of curative-intent multimodal management of chemorefractory nonmetastatic inflammatory breast cancer

INTRODUCTION

Chemorefractory nonmetastatic inflammatory breast cancer (IBC) which progresses under neoadjuvant chemotherapy poses specific therapeutic challenges: either pursuing a curative-intent treatment with a salvage combination of radiotherapy and surgery or switching to second-line systemic treatments despite the absence of metastasis. Due to the rarity of this situation, no specific management guidelines exist and the outcomes of these patients remain uncertain. In this retrospective observational study, we aimed to report the clinical outcomes of patients treated in a curative intent for chemorefractory nonmetastatic IBC, with a multimodal salvage treatment combining radiotherapy and surgery.

MATERIALS AND METHODS

This single-center retrospective observational study included all chemorefractory nonmetastatic IBC treated at the Institut Curie (Paris, France). Overall survival (OS), disease-free survival (DFS), and locoregional relapse-free survival (LRRFS) were calculated from the time of diagnosis and from the time of neoadjuvant chemotherapy interruption.

RESULTS

Between January 2010 and January 2018, 7 patients presented with chemorefractory nonmetastatic IBC with a progressive disease during neoadjuvant chemotherapy. Overall, chemorefractory IBC patients were young (median age of 50 years), had a good performance status, and usually presented with node-positive tumors characterized by a combination of adverse histological factors such as triple-negative breast cancer (TNBC), grade III, and high proliferation index. From the date of pathological diagnosis, 1‑year OS, DFS, and LRRFS were 64.3%, 53.6%, and 71.4%, respectively. From the date of neoadjuvant chemotherapy interruption, 1‑year OS, DFS, and LRRFS were 47.6%, 19.0%, and 45.7%, respectively, and median OS, DFS, and LRRFS were 8.3, 5.0, and 5.0 months, respectively.

CONCLUSION

The prognosis of chemorefractory nonmetastatic IBC treated with a multimodal approach combining surgery and radiotherapy is particularly reserved, despite the curative intent of the salvage treatment and the lack of distant metastasis at the time of treatment. Optimal treatment modalities are still to be defined in this rare but critical presentation of IBC.

[The place of radiotherapy]

Radiation therapy (RT) is a key component of the management of elderly breast cancer patients. However, level I evidence in elderly patients is limited. Patient selection should include comorbidities and geriatric assessment. Advances in radiation planning and delivery are improving target coverage, reducing toxicity, and expanding treatment eligibility. Some alternative techniques, such as treatment in the lateral or prone position, may reduce the risk of toxicity. Shorter cycles of hypofractionated whole breast RT are safe and effective. In some cases, partial breast irradiation may be an option.

Quantitative evaluation of dosimetric uncertainties associated with small electron fields

INTRODUCTION

Although many studies have investigated small electron fields, there are several dosimetric issues that are not well understood. This includes lack of charged particle equilibrium, lateral scatter, source occlusion and volume averaging of the detectors used in the measurement of the commissioning data. High energy electron beams are also associated with bremsstrahlung production that contributes to dose deposition, which is not well investigated, particularly for small electron fields. The goal of this work has been to investigate dosimetric uncertainties associated with small electron fields using dose measurements with different detectors as well as calculations with eMC dose calculation algorithm.

METHODS

Different dosimetric parameters including output factors, depth dose curves and dose profiles from small electron field cutouts were investigated quantitatively. These dosimetric parameters were measured using different detectors that included small ion chambers and diodes for small electron cutouts with diameters ranging from 15-50mm mounted on a 6 × 6cm² cone with beam energies from 6-20MeV.

RESULTS

Large deviations existed between the output factors calculated with the eMC algorithm and measured with small detectors for small electron fields up to 55% for 6MeV. The discrepancy between the calculated and measured doses increased 10%-55% with decreasing electron beam energy from 20 MeV to 6 MeV for 15mm circular field. For electron fields with cutouts 20mm and larger, the measured and calculated doses agreed within 5% for all electron energies from 6-20MeV. For small electron fields, the maximal depth dose shifted upstream and becomes more superficial as the electron beam energy increases from 6-20MeV as measured with small detectors.

DISCUSSION

Large dose discrepancies were found between the measured and calculated doses for small electron fields where the eMC underestimated output factors by 55% for small circular electron fields with a diameter of 15 mm, particularly for low energy electron beams. The measured entrance doses and d_max of the depth dose curves did not agree with the corresponding values calculated by eMC. Furthermore, the measured dose profiles showed enhanced dose deposition in the umbra region and outside the small fields, which mostly resulted from dose deposition from the bremsstrahlung produced by high energy electrons that was not accounted for by the eMC algorithm due to inaccurate modeling of the lateral dose deposition from bremsstrahlung.

CONCLUSION

Electron small field dosimetry require more consideration of variations in beam quality, lack of charged particle equilibrium, lateral scatter loss and dose deposition from bremsstrahlung produced by energetic electron beams in a comprehensive approach similar to photon small field dosimetry. Furthermore, most of the commercially available electron dose calculation algorithms are commissioned with large electron fields; therefore, vendors should provide tools for the modeling of electron dose calculation algorithms for small electron fields.

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.

Quantitative evaluation of dosimetric uncertainties in electron therapy by measurement and calculation using the electron Monte Carlo dose algorithm in the Eclipse treatment planning system

In the electron beam radiation therapy, customized blocks are mostly used to shape treatment fields to generate conformal doses. The goal of this study is to investigate quantitatively dosimetric uncertainties associated with heterogeneities, detectors used in the measurement of the beam data commissioning, and modeling of the interactions of high energy electrons with tissue. These uncertainties were investigated both by measurements with different detectors and calculations using electron Monte Carlo algorithm (eMC) in the Eclipse treatment planning system. Dose distributions for different field sizes were calculated using eMC and measured with a multiple-diode-array detector (MapCheck2) for cone sizes ranging from 6 to 25 cm. The dose distributions were calculated using the CT images of the MapCheck2 and water-equivalent phantoms. In the umbra region (<20% isodose line), the eMC underestimated dose by a factor of 3 for high energy electron beams due to lack of consideration of bremsstrahlung emitted laterally that was not accounted by eMC in the low dose region outside the field. In the penumbra (20%-80% isodose line), the eMC overestimated dose (40%) for high energy 20 MeV electrons compared to the measured dose with small diodes in the high gradient dose region. This was mainly due to lack of consideration of volume averaging of the ion chamber used in beam data commissioning which was input to the eMC dose calculation algorithm. Large uncertainties in the CT numbers (25%) resulted from the image artifacts in the CT images of the MapCheck2 phantom due to metal artifacts. The eMC algorithm used the electron and material densities extracted from the CT numbers which resulted large dosimetric uncertainties (10%) in the material densities and corresponding stopping power ratios. The dose calculations with eMC are associated with large uncertainties particularly in penumbra and umbra regions and around heterogeneities which affect the low dose level that cover nearby normal tissue or critical structures.

Radiotherapy of breast cancer

Adjuvant radiotherapy is an essential component of the treatment of breast cancer. After conservative surgery for an infiltrating carcinoma, radiotherapy must be systematically performed, regardless of the characteristics of the disease, because it decreases the rate of local recurrence and by this way, specific mortality. A boost dose over the tumour bed is required if the patient is younger than 50 years-old. Partial breast irradiation could be routinely proposed as an alternative to whole breast irradiation, but only in selected and informed patients. For ductal carcinoma in situ, adjuvant radiotherapy must be also systematically performed after lumpectomy. After mastectomy, chest wall irradiation is required for pT3-T4 tumours and if there is an axillary nodal involvement, whatever the number of involved lymph nodes. After neoadjuvant chemotherapy and mastectomy, in case of pN0 disease, chest wall irradiation is recommended if there is a clinically or radiologically T3-T4 or node positive disease before chemotherapy. Axillary irradiation is recommended only if there is no axillary surgical dissection and a positive sentinel lymph node. Supra- and infraclavicular irradiation is advised in case of positive axillary nodes. Internal mammary irradiation must be discussed case by case, according to the benefit/risk ratio (cardiac toxicity). Hypofractionation regimens (42.5Gy in 16 fractions, or 41,6Gy en 13 or 40Gy en 15) are equivalent to conventional irradiation and must prescribe after tumorectomy in selected patients. Delineation of the breast, the chest wall and the nodal areas are based on clinical and radiological evaluations. 3D-conformal irradiation is the recommended technique, intensity-modulated radiotherapy must be proposed only in specific clinical situations. Respiratory gating could be useful to decrease the cardiac dose. Concomitant administration of chemotherapy in unadvised, but hormonal treatment could be start with or after radiotherapy.

Should the management of radiation therapy for breast cancer be standardized? Results of a survey on current French practices in breast radiotherapy

Background

Breast cancer is the most frequent cancer in women in France. Its management has evolved considerably in recent years with a focus on reducing iatrogenic toxicity. The radiotherapy indications are validated in multidisciplinary consultation meetings; however, questions remain outstanding, particularly regarding hypofractionated radiotherapy, partial breast irradiation, and irradiation of the internal mammary chain and axillary lymph node area.

Materials and methods

An online survey was sent to 47 heads of radiotherapy departments in France. The survey consisted of 22 questions concerning indications for irradiation of the supraclavicular, internal mammary and axillary lymph node areas; irradiation techniques and modalities; prescribed doses; and fractionation.

Results

Twenty-four out of 47 centers responded (response rate of 51%). This survey demonstrated a wide variation in the prescribed dose regimen, monoisocentric radiotherapy, and indications of irradiation of the lymph node areas.

Conclusion

This survey provides insight into the current radiotherapy practice for breast cancer in France. It shows the need to standardize practices.

Pertuzumab and Trastuzumab Combination with Concomitant Locoregional Radiotherapy for the Treatment of Breast Cancers with HER2 Receptor Overexpression

Simple Summary

This retrospective study demonstrates that the combination of locoregional breast RT with dual HER2 blockade by pertuzumab/trastuzumab was very well tolerated, suggesting that RT can be safely administered to patients with HER2-positive breast cancer during dual HER2 blockade. Excellent locoregional control was achieved in irradiated patients.

Abstract

Background: The combination of pertuzumab and trastuzumab dual HER2 blockade with concomitant curative dose locoregional breast radiotherapy in patients with metastatic breast cancer is an important part of treatment strategy. Methods: This was a retrospective study conducted at the Institut Curie on all patients treated concomitantly with pertuzumab/trastuzumab and locoregional breast radiotherapy. Toxicity was evaluated according to the NCICTCAEv4.0. Overall survival, progression-free survival and locoregional recurrence-free survival were evaluated in metastatic patients who were initially well controlled by chemotherapy, for whom local treatment was decided by the multidisciplinary team. Results: Fifty-five patients treated between October 2013 and December 2019 were included, with a median follow-up of 4.1 years. The median age was 53 years (range: 28–81). All patients received curative dose radiotherapy (RT) concomitantly with pertuzumab and trastuzumab (Pertu/Trastu). The median radiation dose was 50 Gy. Safety evaluation did not reveal any significant adverse effects, with 3 cases of grade 3 radiodermatitis (5.4%), but no significant gastrointestinal or cardiac toxicity. The mean difference in LVEF before any chemotherapy and after radiotherapy was −2.43% (p < 0.01). Conclusions: This study demonstrates that the combination of locoregional breast RT with dual HER2 blockade by Pertu/Trastu was very well tolerated, suggesting that RT can be safely administered to patients with HER2-positive breast cancer.

Eribulin combined with radiation therapy in a young patient re-irradiated for a new lesion of breast cancer

Eribulin is widely used in the treatment of metastatic breast cancer, with a manageable toxicity profile. This aggressive disease often requires systemic and local treatments, comprising surgery or radiotherapy. However, eribulin is usually discontinued during radiation therapy due to the lack of data concerning the safety of this combination, especially in the setting of repeat locoregional radiation therapy. Our patient was diagnosed with ER positive invasive ductal carcinoma of the left breast initially treated by surgery, radiation therapy, chemotherapy, and hormone therapy. She then received various lines of chemotherapy for multiple triple-negative relapses in the left axillary region. Since October 2020, she has been treated by eribulin. In order to improve local control, it was decided to add local radiation therapy to the region of recurrence in addition to systemic therapy. She underwent radiation therapy concomitantly with eribulin from February to March 2021. Treatment was very well tolerated, and no acute toxicity was reported. This is the first published case of repeat locoregional radiation therapy in combination with eribulin.

[Concurrent radiation therapy and dual HER2 blockade in breast cancer: Assessment of toxicity]

PURPOSE

The tolerance of the concurrent use of radiotherapy, pertuzumab and trastuzumab is unknown. The purpose of this study was to evaluate the toxicity of this association in patients treated for HER2 positive metastatic and/or locally recurrent unrespectable breast cancer.

MATERIAL AND METHODS

A retrospective study was performed in our institution for all consecutive patients treated with concurrent irradiation, pertuzumab and trastuzumab. The radiotherapy was performed while pertuzumab and trastuzumab were administrated as a maintenance treatment at the dose of 420mg (total dose) and 6mg/kg respectively every 3 weeks without chemotherapy. Toxicity was assessed according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0. Left ventricular ejection fraction (LVEF) was measured at baseline and then every 3-4 months.

RESULTS

We studied 77 patients. treated in between 2013 and 2019 with median follow-up of 38 months (range 0-264 months). Median age was 53 years (33-86). There were 50 patients (64.9%) with metastatic and 27 patients (35.1%) with recurrent disease. All patients received docetaxel followed by P-T as first line treatment and they received 34 cycles (10-85) of pertuzumab and trastuzumab. All patients experienced partial or complete response according to RECIST criteria. Irradiation volumes were whole breast (41 patients, 53.2%) and chest wall (29 patients, 37.7%) at a dose of 50Gy with a median duration of 39 days. Radiotherapy of lymph nodes was performed in 53 patients (68.8%) as following: supraclavicular-infraclavicular and axillary lymph nodes in 52 patients (67.5%), and internal mammary nodes in 31 patients (40.3%). For 20 patients. (26.0%) radiotherapy was palliative: bone irradiation (12 patients, 15.6%), whole-brain radiotherapy (2 patients, 2.6%), cerebral metastasis irradiation (6 patients). As early toxicity we observed: radio dermatitis as following: 36 patients (46.8%) presented grade I, 17 patients (22.1%) presented grade II, and 3 patients (3.9%) presented grade III. One patient (1.3%) presented grade II esophagitis. One patient (1.3%) presented asymptomatic decrease of LVEF during treatment and 6 patients (7.7%) presented a decrease of LVEF. There was no radiation-induced pneumonitis. As late toxicity, we observed 1 (1.3%) case of grade I and 1 (1.3%) with grade II telangiectasia. There was 1 case (1.3%) of grade III cardiac toxicity, 8 months after the concurrent treatment.

CONCLUSION

The concurrent use of radiotherapy, pertuzumab and trastuzumab is feasible with good tolerance. Larger prospective data with longer follow-up is needed to confirm these results.

Adjuvant Trastuzumab Emtansine (T-DM1) and Concurrent Radiotherapy for Residual Invasive HER2-positive Breast Cancer: Single-center Preliminary Results

OBJECTIVES

The treatment of nonmetastatic HER2-positive breast cancer with residual invasive disease using concurrent Trastuzumab emtansine (T-DM1) and radiotherapy appears to be an effective option. Our aim was to evaluate the acute side effects of this treatment regime.

METHODS

Fourteen patients were treated between March 2019 and April 2020 concurrent T-DM1 and radiotherapy. Left ventricular ejection fraction was assessed at baseline, before and after radiotherapy. All toxicities were evaluated using Common Terminology Criteria of Adverse Events (CTCAE) version 3.0.

RESULTS

The median age was 55 years (range 36 to 72). All patients received total dose of 50 Gy for the breast/ chest wall, 10 patients got lymph node irradiation, 4 patients received an additional tumor bed boost. The most common side effect was grade 1 radiodermatitis. A reversible grade 2 left ventricular ejection fraction decrease occurred in 2 patients. During our examination 3 patients showed alanine aminotransferases increase after the cycle 4 of T-DM1, 1 patient had grade 1, 1 patient grade 2, and 1 patient grade 3 alanine aminotransferase increases.

CONCLUSIONS

The acute toxicity rate especially focusing on skin and cardiac toxicity were assumed acceptable in our cohort. To safely administer this concomitant treatment, further examination and prospective data are needed.

TriB-RT: Simultaneous optimization of photon, electron and proton beams

PURPOSE

To develop a novel treatment planning process (TPP) with simultaneous optimization of modulated photon, electron and proton beams for improved treatment plan quality in radiotherapy.

METHODS

A framework for fluence map optimization of Monte Carlo (MC) calculated beamlet dose distributions is developed to generate treatment plans consisting of photon, electron and spot scanning proton fields. Initially, in-house intensity modulated proton therapy (IMPT) plans are compared to proton plans created by a commercial treatment planning system (TPS). A triple beam radiotherapy (TriB-RT) plan is generated for an exemplary academic case and the dose contributions of the three particle types are investigated. To investigate the dosimetric potential, a TriB-RT plan is compared to an in-house IMPT plan for two clinically motivated cases. Benefits of TriB-RT for a fixed proton beam line with a single proton field are investigated.

RESULTS

In-house optimized IMPT are of at least equal or better quality than TPS-generated proton plans, and MC-based optimization shows dosimetric advantages for inhomogeneous situations. Concerning TriB-RT, for the academic case, the resulting plan shows substantial contribution of all particle types. For the clinically motivated case, improved sparing of organs at risk close to the target volume is achieved compared to IMPT (e.g. myelon and brainstem [Formula: see text] -37%) at cost of an increased low dose bath (healthy tissue V _10% +22%). In the scenario of a fixed proton beam line, TriB-RT plans are able to compensate the loss in degrees of freedom to substantially improve plan quality compared to a single field proton plan.

CONCLUSION

A novel TPP which simultaneously optimizes photon, electron and proton beams was successfully developed. TriB-RT shows the potential for improved treatment plan quality and is especially promising for cost-effective single-room proton solutions with a fixed beamline in combination with a conventional linac delivering photon and electron fields.

Heart-sparing radiotherapy with three-dimensional printing technology after mastectomy for patients with left breast cancer

The purpose of this study was to analyze the effectiveness of electron beam therapy (EBT) with patient-tailored bolus (PTB) using three-dimensional printing technology to reduce heart and lung doses during post-mastectomy radiotherapy (PMRT). For 28 patients with left breast cancer, we designed customized virtual bolus for PMRT to compensate for surface irregularities on computed tomography images and developed optimized plans for EBT. As comparison between the PTB and tangential plans, the PTB plan reduced unnecessary exposure to heart and ipsilateral lung with better target coverage compared with the tangential technique.

Radiation therapy after sentinel lymph node biopsy for early stage breast cancer using a magnetic tracer: Results of a single institutional prospective study of tolerance

PURPOSE

. The aim of the study was, through a single institutional analysis of a large population of breast cancer patients, to assess the feasibility of and the tolerance to radiotherapy after the use of magnetic detection method for sentinel lymph node biopsy.

MATERIAL AND METHODS

The super paramagnetic iron oxide particles database was collected prospectively and identified 520 cases from October 2013 to December 2016 at our institution. All of them received super paramagnetic iron oxide particles injection 20minutes before the surgical procedure and some of them received also isotope technique. Injection site for super paramagnetic iron oxide particles and isotope was periareolar. Among them, 288 patients received adjuvant radiotherapy. In our study, we evaluated the tolerance of postoperative radiotherapy.

RESULTS

The median age of the patients was 64 years. The median follow-up period was 16 months (range: 1-42 months). Double detection of sentinel lymph node was done in the first 30 patients (10.4%). The sentinel lymph node identification rate was 99.7% (287 out of 288). There were 34 axillary lymph node dissections, of which 58.8% were realized straightaway. The total radiation dose was 50Gy EQD2 (range: 28.5-66Gy). Regarding the occurrence of radiodermatitis, 95.8% of patients had grade 0-2 radiodermatitis and 1% had grade 3. During follow-up, 19.4% of patients developed grade 1-2 post-therapeutic fibrosis (of which 92.9% grade 1).

CONCLUSION

The results of this large-scale study show that the radiotherapy after sentinel lymph node biopsy using super paramagnetic iron oxide particles is feasible, and that no increase of the toxicity was observed.

Disseminated Tumor Cells Predict Efficacy of Regional Nodal Irradiation in Early Stage Breast Cancer

PURPOSE

Disseminated tumor cells (DTCs) collect in the bone marrow and indicate micrometastatic spread. We previously reported that DTCs could be a predictive factor for the efficacy of regional node irradiation (internal mammary nodes [IMNs]/supra- and infraclavicular nodes [SCNs]). In this article, we report the long-term results (>10 years) on the impact of DTC status in early stage breast cancer.

METHODS AND MATERIALS

Patients with localized breast cancer were eligible for inclusion in this prospective cohort. DTCs were obtained from a medullary iliac crest sample performed before any primary therapy. DTC status was prospectively assessed by pathologists. Irradiation volumes were defined per standard of care. Cumulative incidence rates and hazard ratios were obtained using both Cox and Fine-Gray models. Interaction tests were performed to confirm the predictive value of DTC status in a multivariate analysis.

RESULTS

Six hundred twenty patients with localized breast cancer were included. Overall, 94 patients (15.2%) were DTC-positive. After a median follow-up of 11.7 years, 47 patients (7.6%) experienced locoregional relapse. DTC detection was associated with a higher risk of locoregional relapse in univariate and multivariate analyses (Cox hazard ratio, 3.26; 95% confidence interval, 1.6-5.7; P = .001). In the multivariate subgroup analysis, IMN/SCN irradiation significantly reduced locoregional relapse among DTC-positive patients compared with DTC-negative patients (interaction test: hazard ratio, 0.3; 95% confidence interval, 0.1-0.9; P = .02). IMN/SCN was the only irradiation volume with an impact on locoregional relapse in patients according to DTC status, and the predictive value of DTC status for the benefit of locoregional irradiation was independent of locoregional nodal status.

CONCLUSIONS

This long-term analysis confirms the predictive impact of DTC status on the efficacy of regional radiation therapy for locoregional relapse in early breast cancer. After further studies, DTC status could be used as a decision tool to better tailor adjuvant radiation therapy in patients with early stage breast cancer.

Patterns of loco regional failure in women with breast cancer treated by Postmastectomy Conformal Electron Beam Radiation Therapy (PMERT): Large scale single center experience

Purpose

To evaluate loco regional control and describe the patterns of loco regional failure in women with breast cancer irradiated by a previously described post-mastectomy highly conformal electron beam radiotherapy technique.

Materials and methods

We included all women irradiated by PMERT for non-metastatic breast cancer (BC) between 2007 and 2011 in our department. All cases of bilateral BC were excluded. All patients who experienced loco regional recurrence have been studied. Mapping patterns of regional recurrences was also performed and compared with the ESTRO and RTOG Guidelines of volume definition and delineation guidelines.

Results

Among the 796 women included, 10.1% were triple-negative (TN) and 18.8% were HER2-positive and 24.6% of them had received neoadjuvant chemotherapy (CT). Internal mammary chain (IMC), supraclavicular (Level IV), infraclavicular (Levels III and II) and axillary LN (Level I) were treated in 85.6%, 88.3%, 77.9% and 14.9% of cases, respectively. With a median follow-up of 64 months (range: 6-102), 5-year locoregional (RFS and OS were 90% (95% CI: 88.1-92.4) and 90.9% (95% CI: 88.9-93), respectively. Twenty-three patients (2.9%) presented locoregional recurrences. Most of them presented aggressive biological features with grade III tumors in 17 patients (74%) with high mitotic index in 16 cases (70%) and triple negative tumors in 12 (52%). Lymphovascular invasion (LVI) was observed in 11 cases (48%). In 14 cases the locoregional recurrences were diagnosed at the same time as the metastatic disease whereas 4 patients presented distant metastases secondarily. Local (Chest wall) recurrences occurred in 13 cases (56%) with the coverage by the isodose of 47.5 Gy (isodose 95%). Fifteen regional recurrences (lymph nodes) were observed in 13 patients. Only 3 regional recurrences occurred within irradiated volumes and 12 regional recurrences occurred outside irradiated areas.

Conclusion

In presented series, the local recurrences were related mostly to the tumor biological aggressivity and radio resistance. Small number was caused by geographical miss. Further follow-up and careful registration of the recurrences is needed to improve their understanding.

Evaluation of various boluses in dose distribution for electron therapy of the chest wall with an inward defect

Delivering radiotherapy to the postmastectomy chest wall can be achieved using matched electron fields. Surgical defects of the chest wall change the dose distribution of electrons. In this study, the improvement of dose homogeneity using simple, nonconformal techniques of thermoplastic bolus application on a defect is evaluated. The proposed phantom design improves the capability of film dosimetry for obtaining dose profiles of a patient's anatomical condition. A modeled electron field of a patient with a postmastectomy inward surgical defect was planned. High energy electrons were delivered to the phantom in various settings, including no bolus, a bolus that filled the inward defect (PB0), a uniform thickness bolus of 5 mm (PB1), and two 5 mm boluses (PB2). A reduction of mean doses at the base of the defect was observed by any bolus application. PB0 increased the dose at central parts of the defect, reduced hot areas at the base of steep edges, and reduced dose to the lung and heart. Thermoplastic boluses that compensate a defect (PB0) increased the homogeneity of dose in a fixed depth from the surface; adversely, PB2 increased the dose heterogeneity. This study shows that it is practical to investigate dose homogeneity profiles inside a target volume for various techniques of electron therapy.

Optimal approach in early breast cancer: Radiation therapy

Radiation therapy significantly reduces by at least 70% the relative risk of local and regional recurrences for breast cancer after surgery. A positive influence on overall survival has been clearly demonstrated, especially for patients with a high absolute risk for locoregional recurrences. However, this is partially counterbalanced by late toxicity (dependent upon the radiation dose) especially to cardiac structures. Apart from this toxicity, a clear influence of radiation-therapy-related factors on functional and cosmetic outcome has also been demonstrated. Over time, technical improvements have led to a marked reduction in dose to the neighbouring organs, with a consequent drop in acute and late toxicity. This has also allowed the introduction of shorter radiation schedules, lowering the burden of treatment to the patient and the hospital. Several tools, techniques and guidelines have been developed to optimise the balance between the desired reduction in recurrence rates and side effects.

The multidisciplinary team should discuss all available treatment options for every individual breast cancer patient. Individualisation of the selection of the optimal combination of treatments, depending on patient and tumour-related factors, is of utmost importance. Apart from direct tumour-related outcomes, cosmesis and potential side effects have to be taken into account. Counselling should include known risk factors for survival and complications, including comorbidity.

Dosimetric verification of gated delivery of electron beams using a 2D ion chamber array

The purpose of this study was to compare the dosimetric characteristics; such as beam output, symmetry and flatness between gated and non-gated electron beams. Dosimetric verification of gated delivery was carried for all electron beams available on Varian CL 2100CD medical linear accelerator. Measurements were conducted for three dose rates (100 MU/min, 300 MU/min and 600 MU/min) and two respiratory motions (breathing period of 4s and 8s). Real-time position management (RPM) system was used for the gated deliveries. Flatness and symmetry values were measured using Imatrixx 2D ion chamber array device and the beam output was measured using plane parallel ion chamber. These detector systems were placed over QUASAR motion platform which was programmed to simulate the respiratory motion of target. The dosimetric characteristics of gated deliveries were compared with non-gated deliveries. The flatness and symmetry of all the evaluated electron energies did not differ by more than 0.7 % with respect to corresponding non-gated deliveries. The beam output variation of gated electron beam was less than 0.6 % for all electron energies except for 16 MeV (1.4 %). Based on the results of this study, it can be concluded that Varian CL2100 CD is well suitable for gated delivery of non-dynamic electron beams.

Design and production of 3D printed bolus for electron radiation therapy

This is a proof‐of‐concept study demonstrating the capacity for modulated electron radiation therapy (MERT) dose distributions using 3D printed bolus. Previous reports have involved bolus design using an electron pencil beam model and fabrication using a milling machine. In this study, an in‐house algorithm is presented that optimizes the dose distribution with regard to dose coverage, conformity, and homogeneity within the planning target volume (PTV). The algorithm takes advantage of a commercial electron Monte Carlo dose calculation and uses the calculated result as input. Distances along ray lines from the distal side of 90% isodose line to distal surface of the PTV are used to estimate the bolus thickness. Inhomogeneities within the calculation volume are accounted for using the coefficient of equivalent thickness method. Several regional modulation operators are applied to improve the dose coverage and uniformity. The process is iterated (usually twice) until an acceptable MERT plan is realized, and the final bolus is printed using solid polylactic acid. The method is evaluated with regular geometric phantoms, anthropomorphic phantoms, and a clinical rhabdomyosarcoma pediatric case. In all cases the dose conformity are improved compared to that with uniform bolus. For geometric phantoms with air or bone inhomogeneities, the dose homogeneity is markedly improved. The actual printed boluses conform well to the surface of complex anthropomorphic phantoms. The correspondence of the dose distribution between the calculated synthetic bolus and the actual manufactured bolus is shown. For the rhabdomyosarcoma patient, the MERT plan yields a reduction of mean dose by 38.2% in left kidney relative to uniform bolus. MERT using 3D printed bolus appears to be a practical, low‐cost approach to generating optimized bolus for electron therapy. The method is effective in improving conformity of the prescription isodose surface and in sparing immediately adjacent normal tissues.

PACS number: 81.40.Wx

Comparison of Chest Wall and Lymphatic Radiotherapy Techniques in Patients with Left Breast Carcinoma

OBJECTIVE

The aim of this study was to find the most appropriate technique for postmastectomy chest wall (CW) and lymphatic irradiation.

MATERIALS AND METHODS

Partially wide tangent, 30/70 photon/electron mix, 20/80 photon/electron mix and CW and internal mammary en face electron field, were studied on computerized tomography (CT) scans of 10 left breast carcinoma patients and dosimetric calculations have been studied. Dose volume histograms (DVH) obtained from treatment planning system (TPS) were used for minimal, maximal and mean doses received by the clinical target volumes and critical structures.

RESULTS

Partially wide tangent field resulted in the most homogeneous dose distribution for the CW and a significantly lower lung and heart doses compared with all other techniques. However, right breast dose was significantly higher for partially wide tangent technique than that each of the other techniques. Approximately 0.6-7.9% differences were found between thermoluminescent dosimeter (TLD) and treatment planning system (TPS). The daily surface doses calculating using Gafchromic® external beam therapy (EBT) dosimetry films were 161.8±2.7 cGy for the naked, 241.0±1.5 cGy when 0.5 cm bolus was used and 255.3±2.7 cGy when 1 cm bolus was used.

CONCLUSION

As a result of this study, partially wide tangent field was found to be the most appropriate technique in terms of the dose distribution, treatment planning and set-up procedure. The main disadvantage of this technique was the higher dose to the contralateral breast comparing the other techniques.

Novel eradicative high-dose rate brachytherapy for internal mammary lymph node metastasis from breast cancer

AIM: To develop a method of delivering an eradicative high radiotherapeutic dose safely preserving the surrounding skin in the treatment of internal mammary lymph node metastasis (IMLNM) of breast cancer.

METHODS: We report a 38-year-old female patient with a solo IMLNM showing no response to 60 Gy in 2.5 Gy fractions of external beam radiotherapy. To eradicate this tumor, a boost brachytherapy plan was created after percutaneous insertion of an applicator needle into the IMLNM lesion avoiding the pleura and vessels under ultrasound monitoring. According to the dose distribution, the required thickness of a spacer between the skin and the tumor was determined, and hyaluronic gel was injected up to this thickness under ultrasound monitoring. We evaluated skin doses, target doses and clinical outcome.

RESULTS: All procedures were performed easily. Sixteen Gy (34.7 Gy equivalent in 2 Gy fractions calculated by the linear quadratic model at α/β = 10: EQD_{2, α/β = 10}, cumulative total was 101.9 Gy EQD10) to 100% of the target volume was irradiated with cumulative maximum skin dose of 70 Gy EQD_{2, α/β = 3} which was 98.7 Gy EQD_{2, α/β = 3} without spacer. No procedure related- or late complications and no local recurrence at the treated site were observed for three years until expiration.

CONCLUSION: We consider that this procedure will provide an eradicative high-dose irradiation to IMLNM of breast cancer, preserving skin from overdose complications.

Quality indicators for breast cancer: revisiting historical evidence in the context of technology changes

Radiation therapy for breast cancer has considerably changed over the years, from simple simulator-based 2-dimensional techniques to sophisticated image-guided individualized treatments, with maximally protected normal structures. This has led to a substantial improvement in the outcome of breast cancer patients in terms of disease control, survival, and quality of life. This progress is based on clinical research and paralleled by progress in delivering sophisticated radiation treatment. Clinical trials resulted in identifying patients groups who will benefit from radiation treatment. They also stimulated the development of quality assurance tools and guidelines, which are now applied in daily clinical practice. The new technical opportunities to optimize dose distributions in patients require dedicated quality assurance measures because they may be more sensitive to variations throughout the treatment. Still, a large source of variation and uncertainty in radiation therapy remains in the definition of target volumes, which is clinically significant in terms of dosimetric target coverage as well as exposure of healthy tissues. This striving for continuous improvement of patient selection and treatment will lead to further improvement of local control while at the same time improving functional and cosmetic outcome and avoiding severe late complications, including cardiac toxicity.

Segmented photon beams technique for irradiation of postmastectomy patients

AIM

To present the segmented photon beams technique (SPBT) for irradiation of postmastectomy patients.

BACKGROUND

In majority of techniques for irradiation of posmastectomy patients, a few adjacent photon or electron beams were usually implemented in order to encompass different parts of the target. In the presented SPBT technique, the radiotherapy plan consists of 6 isocentric photon beams and the area CTV includes both the chest wall and the supraclavicular area. This makes it possible to provide a uniform dose to the CTV with no hot and cold points and enables the determination of doses for the entire volume of critical organs.

METHODS AND MATERIAL

The treatment forward-IMRT plan comprises six isocentric 4 and 15 MV photon beams. Modulation of the dose distribution for each field was obtained by applying three segments on average. The total dose of 45 Gy was administered in 20 fractions. Dose distributions in target volume and organs at risk were evaluated for 70 randomly chosen patients.

RESULTS

On average, 94.8% of the CTV volume received doses within 95-107% of the prescribed dose. The average volume of the heart receiving a dose of 30 Gy and lager was 2% for patients with left breast cancer. The average dose to the lung on the irradiation side was always lower than 15.5 Gy and the average V20 Gy was below 35.5%.

CONCLUSIONS

The SPBT complies with requirements for high dose homogeneity within the target volume and satisfactory level of sparing of organs at risk.

Can we decrease the skin reaction in breast cancer patients using hyaluronic acid during radiation therapy? Results of phase III randomised trial

PURPOSE

Radio-induced early skin reactions still remain a clinical challenge. Preliminary results with Hyaluronic acid, one of the most recent topical products used in this indication are proving interesting. To evaluate the efficacy of Hyaluronic acid compared to placebo.

MATERIAL AND METHODS

Breast cancer patients with grade 1-2 radio-induced dermatitis during postoperative radiotherapy were eligible. They were randomised to receive either hyaluronic acid (A) or a simple emollient (B). The primary endpoint was the clinical evaluation of the erythema (success versus failure). Secondary endpoints were the evaluation of skin colorimetry, pain, and quality of life.

RESULTS

Two-hundred patients were enrolled (A=99, B=101). Ninety-five patients per treatment arm could be evaluated. Failures occurred in 23 patients (24%) in the hyaluronic acid arm, and 32 (34%) in the emollient arm (p=0.15). Seventy-three patients (36.5%) prematurely stopped the treatment without any ensuing difference between the two arms. Body mass index and the size of the epithelitis were both independently associated with the failure of the local treatment. The relative reduction of colorimetric levels was 20% in the hyaluronic acid group, and 13% in the emollient group (p=0.46). Concerning the quality of life assessment, there was a trend towards a lower level of pain in patients receiving hyaluronic acid (p=0.053).

CONCLUSIONS

The present study showed no significant difference between hyaluronic acid and simple emollient in the treatment of acute radio-induced dermatitis. There was however a trend towards an improvement in both pain level and skin colorimetry.

[Radiotherapy for breast cancer and pacemaker]

PURPOSE

Patients with permanent cardiac pacemakers occasionally require radiotherapy. Therapeutic irradiation may cause pacemakers to malfunction due to the effects of ionizing radiation or electromagnetic interference. We studied the breast cancer patients who needed breast and/or chest wall and lymph node irradiation to assess the feasibility and tolerance in this population of patients.

PATIENTS AND METHODS

From November 2008 to December 2009, more than 900 patients received radiotherapy for their breast cancer in our department using megavoltage linear accelerator (X 4-6 MV and electrons). Among them, seven patients were with permanent pacemaker. All patients have been treated to the breast and chest wall and/or lymph nodes. Total dose to breast and/or chest wall was 50 Gy/25 fractions and 46 Gy/23 fractions to lymph nodes. Patients who underwent conserving surgery followed by breast irradiation were boosted when indicated to tumour bed with 16 Gy/8 fractions. All patients were monitored everyday in presence of radiation oncologist to follow the function of their pacemaker. All pacemakers were controlled before and after radiotherapy by the patients' cardiologist.

RESULTS

Seven patients were referred in our department for postoperative breast cancer radiotherapy. Among them, only one patient was declined for radiotherapy and underwent mastectomy without radiotherapy. In four cases the pacemaker was repositioned before the beginning of radiotherapy. Six patients, aged between 48 and 84 years underwent irradiation for their breast cancer. Four patients were treated with conserving surgery followed by breast radiotherapy and two with mastectomy followed by chest wall and internal mammary chain, supra- and infra-clavicular lymph node irradiation. The dose to the pacemaker generator was kept below 2 Gy. There was no pacemaker dysfunction observed during the radiotherapy.

CONCLUSION

The multidisciplinary work with position change of the pacemaker before radiotherapy and everyday monitoring permitted the safe treatment of our patients. Updated guidelines are definitely needed with more details about acceptable doses at the different parts of the pacemaker.