Intraoperative radiation therapy (IORT) in soft-tissue sarcoma

Electron FLASH radiotherapy in vivo studies. A systematic review

FLASH-radiotherapy delivers a radiation beam a thousand times faster compared to conventional radiotherapy, reducing radiation damage in healthy tissues with an equivalent tumor response. Although not completely understood, this radiobiological phenomenon has been proved in several animal models with a spectrum of all kinds of particles currently used in contemporary radiotherapy, especially electrons. However, all the research teams have performed FLASH preclinical studies using industrial linear accelerator or LINAC commonly employed in conventional radiotherapy and modified for the delivery of ultra-high-dose-rate (UHDRs). Unfortunately, the delivering and measuring of UHDR beams have been proved not to be completely reliable with such devices. Concerns arise regarding the accuracy of beam monitoring and dosimetry systems. Additionally, this LINAC totally lacks an integrated and dedicated Treatment Planning System (TPS) able to evaluate the internal dose distribution in the case of in vivo experiments. Finally, these devices cannot modify dose-time parameters of the beam relevant to the flash effect, such as average dose rate; dose per pulse; and instantaneous dose rate. This aspect also precludes the exploration of the quantitative relationship with biological phenomena. The dependence on these parameters need to be further investigated. A promising advancement is represented by a new generation of electron LINAC that has successfully overcome some of these technological challenges. In this review, we aim to provide a comprehensive summary of the existing literature on in vivo experiments using electron FLASH radiotherapy and explore the promising clinical perspectives associated with this technology.

A Novel Treatment Planning Design for Intraoperative Electron Radiation Therapy (IOERT) using an Electronic Board

Background

Intraoperative Irradiation Therapy (IORT) refers to the delivery of radiation during surgery and needs the computed- thickness of the target as one of the most significant factors.

Objective

This paper aimed to compute target thickness and design a radiation pattern distributing the irradiation uniformly throughout the target.

Material and Methods

The Monte Carlo code was used to simulate the experimental setup in this simulation study. The electron flux variations on an electronic board's metallic layer were studied for different thicknesses of the target tissue and validated with experimental data of the electronic board.

Results

Based on the electron number for different Poly Methyl Methacrylate (PMMA) phantom thicknesses at various energies, 6 MeV electrons are suitable to determine the target thickness. Uniformity in radiation and corresponding time for each target were investigated. The iso-dose and percentage depth dose curves show that higher energies are suitable for treatment and distribute uniform radiation throughout the target. Increasing the phantom thickness leads to rising radiation time based on the radiation time corresponding to these energies. The tissue thickness of each section is determined, and the radiation time is managed by scanning the target.

Conclusion

Calculation of the thickness of the remaining tissue and irradiation time are needed after incomplete tumor removal in IORT for various remaining tissues. The patients should be protected from overexposure to uniform irradiation of tissues since the radiation dose is prescribed and checked by an oncologist.

First clinical application of image-guided intraoperative electron radiation therapy with real time intraoperative dose calculation in recurrent rectal cancer: technical procedure

Intraoperative radiation therapy (IORT) is a radiation technique applying a single fraction with a high dose during surgery. We report the first abdomino-pelvic application of an image-guided intraoperative electron radiation therapy with intraoperative real time dose calculation based on the individual intraoperative patient anatomy. A patient suffering from locoregionally recurrent rectal cancer after treatment with neoadjuvant re-chemoradiation was chosen for this approach. After surgical removal of the recurrence, an adequate IORT applicator was placed as usual. A novel mobile imaging device (ImagingRing, MedPhoton) was positioned around the patient covering the region to be treated with the IORT-applicator in place. It allowed the acquisition of three-dimensional intraoperative cone-beam computed tomography images suitable for dose calculation using an automated scaling (heuristic object and head scatter as well as hardening corrections) of Hounsfield units. After image acquisition confirmed the correct applicator position, the images were transferred to our treatment planning system for intraoperative dose calculation. Treatment could be accomplished using the calculated dose distribution. We herein describe the details of the procedure including necessary adjustments in the typically used IORT equipment and work flow. We further discuss the pros and cons of this new approach generally overcoming a decade long limitation of IORT procedures as well as future perspectives regarding IORT treatments.

Survival nomograms for patients with retroperitoneal soft tissue sarcoma based on the SEER database and an external cohort

BACKGROUND

Retroperitoneal soft tissue sarcoma (RPS) is a quite rare disease,and new nomograms need to be constructed to predict the overall survival (OS) and cancer specific survival (CSS) of RPS patients.

METHODS

The clinical data of patients with RPS were extracted from the Surveillance, Epidemiology, and End Results (SEER) database and authors' hospital. The LASSO method and COX proportional hazard regression were used to screen independent risk factors which were used to develop nomograms. Nomograms was evaluated in terms of discrimination by consistency index (C-index) and calibration curve. Decision curve analysis (DCA) and integrated discrimination index (IDI) were performed to assess net benefit and the improvement of model, respectively. Kaplan-Meier method and log-rank test were applied to compare the survival difference between groups.

RESULTS

A total of 1164 cases were enrolled which were divided into training cohort (n = 814) and internal validation cohort (n = 350) at a 7:3 ratio. The discrimination of nomograms were good with C-index of 0.728 (95%CI = 0.704-0.752, R2 = 0.270), 0.754 (95%CI = 0.729-0.779, R2 = 0.281) for OS and CSS, respectively. Calibration curve showed good predictive accuracy of nomograms both in internal and external validation cohort, and IDI indicated that nomograms perform well than AJCC stage. Kaplan Meier curve and log-rank test uncovered statistically significance survival difference between high- and low-risk groups with P < 0.001 in terms of OS and CSS.

CONCLUSION

Novel nomograms predicting the OS and CSS of RPS patients perform well in discrimination, calibration, clinical benefit and IDI. These nomograms may facilitate risk stratification and making clinical decision.

In vivodosimetry in cancer patients undergoing intraoperative radiation therapy

In vivodosimetry (IVD) is an important tool in external beam radiotherapy (EBRT) to detect major errors by assessing differences between expected and delivered dose and to record the received dose by individual patients. Also, in intraoperative radiation therapy (IORT), IVD is highly relevant to register the delivered dose. This is especially relevant in low-risk breast cancer patients since a high dose of IORT is delivered in a single fraction. In contrast to EBRT, online treatment planning based on intraoperative imaging is only under development for IORT. Up to date, two commercial treatment planning systems proposed intraoperative ultrasound or in-room cone-beam CT for real-time IORT planning. This makes IVD even more important because of the possibility for real-time treatment adaptation. Here, we summarize recent developments and applications of IVD methods for IORT in clinical practice, highlighting important contributions and identifying specific challenges such as a treatment planning system for IORT. HDR brachytherapy as a delivery technique was not considered. We add IVD for ultrahigh dose rate (FLASH) radiotherapy that promises to improve the treatment efficacy, when compared to conventional radiotherapy by limiting the rate of toxicity while maintaining similar tumour control probabilities. To date, FLASH IORT is not yet in clinical use.

Comparing the DNA-damage RBE of intraoperative and conventional electron beams using a hybrid simulation approach

PURPOSE

Employing electron beam for radiotherapy purposes now has been established as one of the standard cancer treatment modalities. Both dedicated intraoperative and conventional electron beams can be employed in patient irradiation. Due to the differences between accelerating structure and electron beam delivery of dedicated intraoperative radiotherapy (IORT) machines and conventional ones, the initial energy spectra of the produced electron beam by these machines may be different. Accordingly, this study aims to evaluate whether these spectral differences can affect the relevant relative biological effectiveness (RBE) values of intraoperative and conventional electron beams.

MATERIALS AND METHODS

A hybrid Monte Carlo simulation approach was considered. At first, the head LIAC12 machine (as an IORT accelerator) and Varian 2100C/D (as a conventional accelerator) were simulated by MCNPX code and electron energy spectra at different depths and off-axis distances were scored for two nominal electron energies of 6 and 12 MeV at the field sizes of 6 and 10 cm. Then, the calculated spectra were imported to MCDS code to estimate the induced DNA-damage RBE values. Finally, the obtained RBE values for intraoperative and conventional electron beams were compared together.

RESULTS

The results showed that the RBE values of the intraoperative electron beam are superior to those obtained for conventional electron beam at the same energy/field size combination. Variations of the depth can regularly affect the RBE value for both conventional and intraoperative electron beams, while no ordered variation trend was observed for RBE with changing the off-axis distance. Variations of electron energy and field size can also influence the RBE value for both types of studied electron beams.

CONCLUSIONS

From the results, it can be concluded the structural differences between the dedicated IORT and conventional Linacs can lead to distinct initial electron energy spectra for intraoperative and conventional electron beams. These physical differences can finally lead to different RBE values for intraoperative and conventional electron beams at the same energy and field size.

An open-source development based on photogrammetry for a real-time IORT treatment planning system

PURPOSE

This study presents a treatment planning system for intraoperative low-energy photon radiotherapy based on photogrammetry from real images of the surgical site taken in the operating room.

MATERIAL AND METHODS

The study population comprised 15 patients with soft-tissue sarcoma. The system obtains the images of the area to be irradiated with a smartphone or tablet, so that the absorbed doses in the tissue can be calculated from the reconstruction without the need for computed tomography. The system was commissioned using 3D printing of the reconstructions of the tumor beds. The absorbed doses at various points were verified using radiochromic films that were suitably calibrated for the corresponding energy and beam quality.

RESULTS

The average reconstruction time of the 3D model from the video sequence in the 15 patients was 229,6±7,0 s. The entire procedure, including video capture, reconstruction, planning, and dose calculation was 520,6±39,9 s. Absorbed doses were measured on the 3D printed model with radiochromic film, the differences between these measurements and those calculated by the treatment planning system were 1.4% at the applicator surface, 2.6% at 1 cm, 3.9% at 2 cm and 6.2% at 3 cm.

CONCLUSIONS

The study shows a photogrammetry-based low-energy photon IORT planning system, capable of obtaining real-time images inside the operating room, immediately after removal of the tumor and immediately before irradiation. The system was commissioned with radiochromic films measurements in 3D-printed model.

SOFT TISSUE SARCOMA - SANTA CASA DE SÃO PAULO EXPERIENCE FROM 2006 TO 2019

Objective

To conduct an epidemiologic review, analyzing treatment, evolution, and survival of soft tissue sarcomas.

Methods

Retrospective study based on medical records of patient with STS treated by the Orthopedic Oncology Group at the Santa Casa de São Paulo, from 2006 to 2019. Data from 121 patients were analyzed according to age, sex, histological type, tumor location, treatment, previous surgery in a non-specialized service, local recurrences, lung metastases, and survival analysis.

Results

The most frequent location was the thigh. Patients who underwent surgery with a non-specialized group had higher rates of local recurrence and those with pulmonary metastasis had a lower survival rate.

Conclusion

STS can occur at any age and the prevalence of the histological type depends on the patients' age group. Level of Evidence II, Prognostic Study.

Updated Review and Clinical Recommendations for the Diagnosis and Treatment of Patients with Retroperitoneal Sarcoma by the Spanish Sarcoma Research Group (GEIS)

Soft tissue sarcomas (STS) are an uncommon and biologically heterogeneous group of tumors arising from mesenchymal cells. The incidence is estimated at five cases per 100,000 people per year. Retroperitoneal sarcomas (RPS) account for 10-15% of all STS, and their management depends on their anatomical characteristics and histotype. Due to their very low incidence, it is recommended that RPS be treated in reference centers and evaluated by an experienced multidisciplinary team (MDT). In Spain, the Spanish Group for Research in Sarcomas (GEIS) brings together experts from various specialties to promote research on sarcomas and improve treatment results. This paper summarizes the GEIS recommendations for the diagnosis, treatment, and follow-up of patients with RPS.

Brachytherapy in the Treatment of Soft-Tissue Sarcomas of the Extremities-A Current Concept and Systematic Review of the Literature

INTRODUCTION

Evidence on the use of brachytherapy in soft-tissue sarcoma (STS) is sparse. Therapy regimens are determined more by local interdisciplinary tumor conferences than by standardized protocols. Patient-specific factors complicate the standardized application of therapy protocols. The individuality of the treatment makes it difficult to compare results.

MATERIALS AND METHODS

A comprehensive literature search was conducted, whereby the literature from a period of almost 44 years (1977-2021) was graded and included in this systematic review. For this purpose, PubMed was used as the primary database. Search string included "soft-tissue sarcoma", "brachytherapy", and "extremity." Four independent researchers reviewed the literature. Only full-text articles written in English or German were included.

RESULTS

Of the 175 identified studies, 70 were eligible for analysis based on the inclusion and exclusion criteria. The key points to compare were local complications, recurrence rate and correlation with margins of resection, and the use of brachytherapy regarding tumor grading.

CONCLUSION

Brachytherapy represents an important subset of radiotherapy techniques used in STSs, whose indications and applications are constantly evolving, and for which a local control rate of 50% to 96% has been reported as monotherapy, depending on risk factors. However, the best benefit is seen in the combination of further resection and brachytherapy, and most authors at many other centers agree with this treatment strategy.

Surgical Principles of Primary Retroperitoneal Sarcoma in the Era of Personalized Treatment: A Review of the Frontline Extended Surgery

Simple Summary

Surgery is the only curative treatment for localized disease in retroperitoneal sarcoma (RPS). Frontline extended surgery, or compartmental surgery, is a recent surgical strategy consisting of resecting the tumor together with adjacent organs, with the aim of minimizing marginality. This review provides a practical step by step description of this standardized procedure, tailored to histologic behavior, tumor localization, and patient condition.

Abstract

Surgery is the key treatment in retroperitoneal sarcoma (RPS), as completeness of resection is the most important prognostic factor related to treatment. Compartmental surgery/frontline extended approach is based on soft-tissue sarcoma surgical principles, and involves resecting adjacent viscera to achieve a wide negative margin. This extended approach is associated with improved local control and survival. This surgery must be tailored to tumor histology, tumor localization, and patient performance status. We herein present a review of compartmental surgery principles, covering the oncological and technical basis, and describing the tailored approach to each tumor subtype and localization in the retroperitoneum.

Well-differentiated mesenteric liposarcoma: report of two cases

Liposarcoma is a rare tumor that can be treated by surgery in the absence of distant metastases. Management of liposarcoma, including diagnosis and therapy, is challenging because it has no characteristic symptoms and no established effective treatment. Here, we report two rare cases of primary mesenteric liposarcoma. In the first case, the tumor caused small bowel obstruction, and the patient presented with abdominal distention and severe abdominal pain. The second case is an occasional finding that occurred during laparoscopic surgery for incisional hernia. Both patients underwent successful resection of the tumor. Histopathology found a well-differentiated liposarcoma in both cases.

The Therapeutic Potential of FLASH-RT for Pancreatic Cancer

Simple Summary

Ultra-high dose rate radiation, widely nicknamed FLASH-RT, kills tumors without significantly damaging nearby normal tissues. This selective sparing of normal tissue by FLASH-RT tissue is called the FLASH effect. This review explores some of the proposed mechanisms of the FLASH effect and the current data that might support its use in pancreatic cancer. Since radiation for pancreatic cancer treatment is limited by GI toxicity issues and is a disease with one of the lowest five-year survival rates, FLASH-RT could have a large impact in the treatment of this disease with further study.

Abstract

Recent preclinical evidence has shown that ionizing radiation given at an ultra-high dose rate (UHDR), also known as FLASH radiation therapy (FLASH-RT), can selectively reduce radiation injury to normal tissue while remaining isoeffective to conventional radiation therapy (CONV-RT) with respect to tumor killing. Unresectable pancreatic cancer is challenging to control without ablative doses of radiation, but this is difficult to achieve without significant gastrointestinal toxicity. In this review article, we explore the propsed mechanisms of FLASH-RT and its tissue-sparing effect, as well as its relevance and suitability for the treatment of pancreatic cancer. We also briefly discuss the challenges with regard to dosimetry, dose rate, and fractionation for using FLASH-RT to treat this disease.

Embedded bleeding detector into a PMMA applicator for electron intraoperative radiotherapy

PURPOSE

The aim of this work is to present a ready to industrialize low-cost and easy-to-install bleeding detector for use in intraoperative electron radiation therapy (IOERT). The detector works in stand-alone mode and is embedded into a translucent polymethylmethacrylate (PMMA) applicator avoiding any contact with the patient, which represent a novelty compared to previous designs. The use of this detector will prevent dose misadministration during irradiation in the event of accumulation of fluids in the applicator.

METHODS

The detector is based on capacitive sensor and wireless power-supply electronics. Both sensor and electronics have been embedded in the applicator, so that any contact with the patient would be avoided. Since access to the tumor can be done through different trajectories, the detector has been calibrated for different tilting angles.

RESULTS

The result of the calibration provides us with a fit curve that allows the interpolation of the results at any angle. Comparison of estimated fluid height vs real height gives an error of 1 mm for tilting angles less than 10° and 2 mm for tilting angles greater than 15°. This accuracy is better than the one required by clinic.

CONCLUSIONS

The performance of the bleeding detector was evaluated in situ. No interference was observed between the detector and the beam. In addition, a user-friendly mobile application has been developed to help the surgical team making decisions before and during irradiation. The measurement provided by the mobile application was stable during the irradiation process.

The role of radiotherapy in adult soft tissues sarcoma of the extremities

Local management of adult soft tissue sarcoma of the extremities has evolved over the past decades. Until the 1970s, radical surgery (amputations) was the standard therapeutic procedure resulting in significant physical and psychological morbidity for the patients. In the present era, limb sparing surgery combined with radiotherapy represents the current standard of care for high grade and > 5 cm STSs. This approach guarantees high local control rate and function preservation. The aim of this paper is to summarize the current evidence for RT in STSs of the extremities. Outcomes, technical details (techniques, timing, dose, volumes of treatment) and the emerging role of RT in the management of oligometastatic disease will be analysed. Finally, results of the recent clinical trials testing new scenarios in RT of STSs will be described.

Leiomyosarcoma of ileal mesentery in a middle age female: a rare case report

Background

Leiomyosarcoma arising from mesentery is a rare tumor associated with worse prognosis. The tumor arises from smooth muscles in vascular wall. Ileal mesentery is common site of this tumor origin.

Case presentation

A middle age female was presented with complain of abdominal distension. A mass was palpable on abdominal examination. CT scan showed large mesenteric cyst. 15 × 10 cm large mass excised with associated mesentery and small bowel segment and on histopathology was found, and it was diagnosed as mesenteric leiomyosarcoma. The patient was discharged and referred to oncology for chemotherapy.

Conclusion

Leiomyosarcoma is a rare disease with grave prognosis. There is a paucity of literature and proper guidelines for its management; however, surgical excision with healthy margins is a mainstay of management. Close follow-up is recommended post-operatively because there are high chances of recurrence and metastasis.

Surgical resection, intraoperative radiotherapy and immediate plastic reconstruction: A good option for the treatment of distal extremity soft tissue sarcomas

Aim

To show three patients with soft tissue sarcomas of distal extremities conservatively treated after tumor-board discussion, involving margin-free surgery, exclusive intraoperative radiotherapy, and immediate reconstruction.

Background

Current guidelines show clear and robust recommendations regarding the composition of the treatment of sarcomas of extremities. However, little evidence exists regarding the application of these treatments depending on the location of the primary neoplasia. Tumors that affect the distal extremities present different challenges and make multidisciplinary discussions desirable.

Methods/Results

We reported 3 patients who were approached with a conservative intention, after tumor board recomendation. The goals from the treatment performed were aesthetic and functional preservation, while enruring locoregional control. We had wound healing complications in 2 of the cases, requiring additional reconstruction measures. Patients are followed up for 24, 20 and 10 months; local control is 100%, and functional preservation is 100%.

Conclusions

Despite being a small series, it was sufficient to illustrate successful multidisciplinary planning, generating a therapeutic result with improved quality of life for patients who had an initial indication for extremity amputation.

Intraoperative radiation therapy in non-breast cancer patients: A report of 26 cases from Shiraz, south of Iran

Background: Intraoperative radiation therapy (IORT) is the delivery of radiation at the time of surgery. Whereas the dose delivered by external beam radiation therapy (EBRT) is limited by the tolerance of the surrounding normal tissues, IORT allows exclusion of a part or all of the dose-limiting sensitive structures by operative mobilization and/or direct shielding of these structures. The aim of the present study was to report the non-breast cancer patients' outcomes after receiving IORT in Shiraz, Iran. Methods: In this retrospective study, all cases who had received IORT and had non-breast malignancies were selected. Diagnosis was confirmed by biopsy. Additional imaging was done by sonography, magnetic resonance imaging (MRI) and computed tomography (CT). IORT was applied by self-shielded, LIAC 6-12 MeV Sordina mobile linear accelerator. Typically, a single dose of 10-21 Gy was given for maximally resected tumors. The statistical analyses were carried out using SPSS (version 21). Results: Twenty-six patients were treated with IORT alone or combined with EBRT. Different tumors were treated, including colorectal adenocarcinoma (10 cases, 38.4 %), Soft Tissue Sarcomas (STS, 11 cases, 42.3 %), head and neck cancers (3 cases, 11.5 %), one cervix malignancy case and one paravertebral fibromatosis case. Mean ± SD overall survival was 15±14.89 (0-38) and 34.3±15.72 (14-53) months for colorectal cancer and STS, respectively. Conclusion: IORT is mostly useful for pelvic and abdominal malignancies where normal bowel limits the dose that can be delivered with EBRT. However, the dose delivered in a single fraction with IORT is rarely sufficient for tumor control; therefore, IORT is usually preceded or followed by additional EBRT which should be further evaluated preferably in prospective randomized trials.

Identification of a survival-related signature for sarcoma patients through integrated transcriptomic and proteomic profiling analyses

Sarcoma (SARC) represents a group of highly histological and molecular heterogeneous rare malignant tumors with poor prognosis. There are few proposed classifiers for predicting patient's outcome. The Cancer Proteome Atlas (TPCA) and The Cancer Genome Atlas (TCGA) databases provide multi-omics datasets that enable a comprehensive investigation for this disease. The proteomic expression profile of SARC patients along with the clinical information was downloaded. 55 proteins were found to be associated with overall survival (OS) of patients using univariate Cox regression analysis. We developed a prognostic risk signature that comprises seven proteins (AMPKALPHA, CHK1, S6, ARID1A, RBM15, ACETYLATUBULINLYS40, and MSH6) with robust predictive performance using multivariate Cox stepwise regression analysis. Additionally, the signature could be an independent prognostic predictor after adjusting for clinicopathological parameters. Patients in high-risk group also have worse progression free intervals (PFI) than that of patients in low-risk group, but not for disease free intervals (DFI). The signature was validated using transcriptomic profile of SARC patients from TCGA. Potential mechanisms between high- and low-risk groups were identified using differentially expressed genes (DEGs) analysis. These DEGs were primarily enriched in RAS and MPAK signaling pathways. The signature protein molecules are candidate biomarkers for SARC, and the analysis of computational biology in tumor infiltrating lymphocytes and immune checkpoint molecules revealed distinctly immune landscapes of high- and low-risk patients. Together, we constructed a prognostic signature for predicting outcomes for SARC integrating proteomic and transcriptomic profiles, this might have value in guiding clinical practice.

Neoadjuvant Radiotherapy-Related Wound Morbidity in Soft Tissue Sarcoma: Perspectives for Radioprotective Agents

Historically, patients with localized soft tissue sarcomas (STS) of the extremities would undergo limb amputation. It was subsequently determined that the addition of radiation therapy (RT) delivered prior to (neoadjuvant) or after (adjuvant) a limb-sparing surgical resection yielded equivalent survival outcomes to amputation in appropriate patients. Generally, neoadjuvant radiation offers decreased volume and dose of high-intensity radiation to normal tissue and increased chance of achieving negative surgical margins-but also increases wound healing complications when compared to adjuvant radiotherapy. This review elaborates on the current neoadjuvant/adjuvant RT approaches, wound healing complications in STS, and the potential application of novel radioprotective agents to minimize radiation-induced normal tissue toxicity.

Phantom development for daily checks in electron intraoperative radiotherapy with a mobile linac

PURPOSE

IORT with mobile linear accelerators is a well-established modality where the dose rate and, therefore, the dose per pulse are very high. The constancy of the dosimetric parameters of the accelerator has to be checked daily. The aim of this work is to develop a phantom with embedded detectors to improve both accuracy and efficiency in the daily test of an IORT linac at the surgery room.

METHODS

The developed phantom is manufactured with transparent polymethyl methacrylate (PMMA), allocating 6 parallel-plate chambers: a central one to evaluate the on-axis beam output, another on-axis one placed at a fixed depth under the previous one to evaluate the energy constancy and four off-axis chambers to evaluate the flatness and symmetry. To analyse the readings a specific application has been developed.

RESULTS

For all chambers and energies, the mean saturation and polarization corrections were smaller than 0.7%. The beam is monitored at different levels of the clinical beam. Output, energy constancy and flatness correlate very well with the correspondent values with the complete applicator. During the first six months of clinical use the beam dosimetric parameters showed excellent stability.

CONCLUSIONS

A phantom has been developed with embedded parallel plate chambers attached to the upper applicator part of an IORT linac. The phantom allows a very efficient setup reducing the time to check the parameters. It provides complete dosimetric information (output, energy and flatness) with just one shot and using ionization chambers with minimum saturation effect, as this highly pulsed beam requires.

Intraoperative radiation therapy (IORT) for soft tissue sarcoma - ESTRO IORT Task Force/ACROP recommendations

PURPOSE

To describe guidelines for the use of intraoperative radiation therapy (IORT) in the treatment of soft-tissue sarcomas (STS).

METHODS

A panel of experts in the field performed a systematic literature review, supplemented their clinical experience and developed recommendations for the use of IORT in the treatment of STS.

RESULTS

Based on the evidence from the systematic literature review and the clinical experience of the panel members, recommendations regarding patient selection, incorporation into multimodal treatment concepts and the IORT procedure itself are made. The rationale for IORT in extremity and retroperitoneal STS is summarized and results of the major series in terms of patient and treatment characteristics, oncological outcome and toxicity are presented. We define surgical factors, volumes for irradiation, technical requirements, dose prescription, recording and reporting, treatment delivery and care during the course of IORT covering the main IORT techniques used for the treatment of STS. In extremity STS, evidence originates from a few small prospective and mainly from retrospective single centre studies. Based on those reports, IORT containing-approaches result in very high local control rates with low rates of acute and late toxicity. In retroperitoneal sarcomas, evidence is derived from one prospective randomized trial, a few prospective and a large number of retrospective studies. The randomized trial compared IORT combined with moderate doses of postoperative external-beam radiation therapy (EBRT) to high-dose postoperative EBRT alone after gross total resection, clearly favouring the IORT-containing approach. These results have been confirmed by the prospective and retrospective studies, which similarly showed high local control rates with acceptable toxicity, mainly favouring combinations of preoperative EBRT and IORT.

CONCLUSIONS

IORT-containing approaches result in high rates of local control with low to acceptable toxicity rates. Based on the available evidence, we made recommendations for the use of IORT in STS. Clinicians and researchers are encouraged to use these guidelines in clinical routine as well as in the design of future trials.

Intraoperative radiotherapy with low energy x-rays for primary and recurrent soft-tissue sarcomas

Background

Soft tissue sarcomas (STS) treatment remains a therapeutic challenge. Intraoperative radiotherapy (IORT) resembles a safe and efficient for STS treatment. The first data on electronic-IORT (eIORT) using low-energy photons is herein presented.

Methods

Thirty-one patients with newly and recurrent STS were retrospectively assessed. EIORT was applied with low-energy photons during surgery. The dose was either prescribed to the applicator surface (spherical applicators) or 5 mm depth (flat applicators). Overall progression-free survival (O-PFS), local progression-free survival (L-PFS), overall survival (OS) and adverse events were evaluated.

Results

Median follow-up was 4.88 (1.0–8.95) years. Twenty-five patients (80.6%) had recurrent STS with prior treatment. The resection status was R1 in 25.8% and R2 in 6.5%. The distribution was 51.7% for extremities, 35.5% for abdomen and pelvis, 9.7% for thorax and 3.2% for head and neck tumors. The median O-PFS was 11.0 months, with 42.6% 5-year estimated O-PFS. The only local recurrence in the primary setting occurred after 22 months. Median L-PFS in recurrent STS was 12.5 months, with 65.5% 5-year estimated L-PFS. The 5-year OS estimated rate was 94.7% (3 events after 7 years). No G3 toxicity related to eIORT was observed. Two patients exhibited G2 acute neuropathic pain. Late neuropathic pain was seen in 6 patients being 3 graded as G1 and 3 as G2. No wound-related toxicity was found.

Conclusion

Electronic IORT with low-energy photons is a safe treatment option for STS, yielding similar outcomes as historical series reporting IORT with electrons or HDR brachytherapy.

Intraoperative Strahlentherapie – Indikationen und Optionen in der Viszeralchirurgie

Hintergrund

Die intraoperative Strahlentherapie (IORT) ermöglicht durch die chirurgische Exposition des Tumors und des Tumorbetts eine hohe Präzision, welche eine hohe Strahlendosis im Bereich des Tumors zulässt und gleichzeitig gesundes Gewebe als den dosislimitierenden Faktor vor Strahlung schützt. Aus diesem Grund bietet die IORT besonders dann einen Vorteil, wenn die lokale Tumorkontrolle das Langzeitüberleben entscheidend beeinflusst und Funktionserhalt ermöglicht.

Ziel der Arbeit

Die in dieser Übersichtsarbeit aufgearbeiteten Erkenntnisse aus der Literaturrecherche erlauben einen evidenzbasierten Umgang hinsichtlich Indikationen und Therapieoptionen der IORT für intraabdominelle Tumoren.

Ergebnisse und Schlussfolgerung

Die Effektivität der IORT kann anhand der vorhandenen Evidenzlage nicht abschließend beurteilt werden, jedoch ist die IORT als Ergänzung der multimodalen Therapie bei (Rezidiv‑)Rektumkarzinomen und Sarkomen aktiv im klinischen Alltag etabliert. Magen- und Pankreaskarzinome stellen weitere Indikationen dar; ergänzende Studien sind jedoch notwendig, um die Rolle der IORT hier klar zu definieren. Ein wesentlicher Faktor, damit für Patienten mit primärem Karzinom und insbesondere für Patienten mit lokalem Rezidiv verbesserte lokale Rezidiv- und Überlebensraten erreicht werden können, scheint die Patientenselektion zu sein.

Multidisciplinary treatment of soft tissue sarcomas: An update

Standard treatment for soft tissue sarcoma, based on complete surgical resection with or without adjuvant radiotherapy and chemotherapy, has not substantially changed during the last several decades. Nevertheless, recent advances have contributed to considerable improvement in the management of these patients; for example, new magnetic resonance imaging sequences such as diffusion-weighted imaging and magnetic resonance imaging radiomics can better assess tumor extension and even estimate its grade. Detection of circulating genetic material (liquid biopsy) and next-generation sequencing are powerful techniques for genetic analysis, which will increase our understanding of the underlying molecular mechanisms and may reveal potential therapeutic targets. The role of chemotherapy in non-metastatic disease is still controversial, and there is a need to identify patients who really benefit from this treatment. Novel chemotherapeutic regimens have entered clinical praxis and can change the outcome of patients with metastatic disease. Advances in radiotherapy have helped decrease local adverse effects and sustain good local control of the disease. The following report provides an updated view of the diagnosis, treatment, and future perspectives on the management of patients with soft tissue sarcomas.

Soft Tissue Tumors of the Abdomen and Retroperitoneum

Soft tissue tumors of the abdomen and retroperitoneum encompass a wide range of benign and malignant neoplasms. Retroperitoneal sarcomas, the most common, are composed of rare malignancies with numerous histiotypes. Surgery remains the cornerstone of treatment and the only curative option for retroperitoneal sarcomas. With histiotype-dependent local and distant recurrences, it is imperative these cases are discussed in a multidisciplinary tumor board setting at specialized sarcoma centers. This review discusses the current evidence for the management of abdominal and retroperitoneal soft tissue tumors, with particular focus on retroperitoneal sarcomas and desmoid tumors.

Intraoperative radiotherapy as an immediate adjuvant treatment of rectal cancer due to limited access to external-beam radiotherapy

BACKGROUND

Neoadjuvant external-beam radiotherapy (EBRT) with concomitant chemotherapy is the current standard-of-care for locally-advanced rectal cancer. Intraoperative radiotherapy (IORT) is to date only recommended for pelvic recurrences or incompletely resectable tumors. We here report on patients with stage II/III rectal cancer that were treated with IORT in a regional Russian university center due to limited access to EBRT.

METHODS

We retrospectively analyzed data from patients that were diagnosed with locally-advanced rectal cancer and underwent surgery from December 2012 to October 2016 at a regional oncological center in Russia (Krasnodar). During this period, access to EBRT was limited due to a temporary lack of a sufficient number of EBRT facilities. Patients unable to travel to a distant radiotherapy site received IORT alone, those that could travel received neoadjuvant external beam (chemo-) radiotherapy. Factors of interest were tumor stage, tumor differentiation, resection status, surgery type and neoadjuvant or adjuvant chemotherapy. We assessed local progression-free survival (L-PFS), PFS and overall survival (OS).

RESULTS

A total of 172 patients were included in this analysis. Of those, 92 (53.5%) were treated with IORT alone (median dose: 15 Gy [8.4-17 Gy]) and 80 (46.5%) received both neoadjuvant EBRT (median dose: 50.4 Gy [40-50.4 Gy]) and IORT (median dose: 15 Gy [15-17 Gy]). The median age was 65 years [33-82]. The median follow-up was 23 months [0-63 months]. The incidence of toxicity was low in both groups with an overall complication rate of 5.4%. Local PFS at 4 years was comparable with 59.4% in the IORT group and 65.4% in the IORT/EBRT group (p = 0.70). Similarly, there was no difference in OS or PFS (p = 0.66, p = 0.51, respectively).

CONCLUSIONS

IORT is a valuable option for patients with locally-advanced rectal cancer in the absence of access to EBRT.

Electron radiotherapy (IOERT) for applications outside of the breast: Dosimetry and influence of tissue inhomogeneities

PURPOSE

The purpose of study is to investigate the dosimetry of electron intraoperative radiotherapy (IOERT) of the Intraop Mobetron 2000 mobile LINAC in treatments outside of the breast. After commissioning and external validation of dosimetry, we report in vivo results of measurements for treatments outside the breast in a large patient cohort, and investigate if the presence of inhomogeneities can affect in vivo measurements.

METHODS AND MATERIALS

Applicator factors and profile curves were measured with a stereotactic diode. The applicators factors of the 6 cm flat and beveled applicators were also confirmed with radiochromic films, parallel-plate ion chamber and by an external audit performed with ThermoLuminescent Dosimeters (TLDs). The influence of bone on dose was investigated by using radiochromic films attached to an insert equivalent to cortical bone, immersed in the water phantom. In vivo dosimetry was performed on 126 patients treated with IOERT using metal oxide-silicon semiconductor field effect transistors (MOSFETs) placed on the tumor bed.

RESULTS

Relatively small differences were found among different detectors for measurements of applicator factors. In the external audit, the agreement with the TLD was mostly within ±0.2%. The largest increase of dose due to the presence of cortical bone insert was +6.0% with energy 12 MeV and 3 cm applicator. On average, in vivo dose was significantly (+3.1%) larger than prescribed dose.

CONCLUSION

IOERT in applications outside the breast results in low discrepancies between in vivo and prescribed doses, which can be also explained with the presence of tissue inhomogeneity.

Update in pelvic and retroperitoneal sarcoma management: The role of compartment surgery

Surgery for retroperitoneal sarcomas should be "en bloc" compartmental, which involves resection of unaffected organs. Its upfront use is key, providing a high percentage of resections with negative margins, resulting in a better local control and increased survival in many patients. Preservation of organs should be done in an individualized manner, especially in the pelvic location, and adapted to the histological aggressiveness of the tumor. Preoperative biopsy is able to establish the diagnosis of sarcoma subtype and consequently an adequate perioperative strategy. These patients should be managed by expert surgeons at referral centers with multidisciplinary units and oncology committees. The use of chemotherapy and radiotherapy is not yet well defined, so it is only recommended at referral centers with clinical trials. Currently, this is the only option to offer the best morbidity and mortality rates, as well as possible improvements in the survival of these patients.

Improving bleeding detector features for electron intraoperative radiotherapy

PURPOSE

The aim of this work is to improve the potential bleeding detection during intraoperative radiotherapy with linac polymethyl methacrylate applicators (PMMA), based on one previously developed. The improvements carried out have been focused on: i) minimizing the impact of the detector on the visual through the plastic applicators and ii) avoiding the asymmetry in the detection capability when the applicator is tilted.

METHODS

Simulations have been made to select the geometry that provides a reduced visual impact on the applicator as well as allowing an independent response with the tilting angle of the applicator. A low-noise circuit for signal conditioning has been developed. Measurements have been made on three setups: 10 cm, 7 cm and 4 cm applicator diameters, 0° and 45° tilted.

RESULTS

The detector has a visibility through the applicator greater than 50%. Due to the geometry, optimal detection is ensured regardless of its orientation when the applicator is tilted. It is possible to detect the presence of fluid well below the typical perturbing fluid depth established by the clinic (1-1.5 cm).

CONCLUSIONS

The detector can distinguish the presence of around 0.5 cm of fluid depth while showing a high visual field through the PMMA applicators and providing a measure that does not depend on the detector orientation when the applicator is tilted. The prototype is ready for its industrialization by embedding it into the applicator for clinical use. The detector would have a significant impact on both the quality assurance and the outcome of the treatment.

Detector for monitoring potential bleeding during electron intraoperative radiotherapy

PURPOSE

The aim of this work is to develop a bleeding detector integrated into the acrylic circular applicators for specific mobile linacs. Thus, a bleeding detector has been developed based on a capacitive sensor to be used with plastic applicators, as in the case of LIAC HWL from Sordina IORT Technologies SpA. According to the clinical impact, we have selected 0.5 cm as the minimum depth of fluid that should be detected.

METHODS

An experiment was developed using water-simulating blood. Two setups were considered: non-beveled applicators with 7 cm and 10 cm diameter. Measurements were done for applicators 0° and 45° tilted, both with respect to the horizontal surface, in order to mimic the worst clinical scenario according to the irradiation gantry and applicator bevel angle. The behavior of the detector under irradiation was analyzed and the impact of the stray radiation on the detector was also evaluated.

RESULTS

The detector was able to distinguish the presence of liquid at a minimum height of 0.5 cm. A linear behavior was obtained for both setups. We have also verified that the LIAC HWL radiation does not affect the measurements nor does the detector interfere with the stray radiation. The bleeding detector is a quasi-digital capacitive sensor with low-cost, high linearity, and easy to install.

CONCLUSIONS

With this detector it is possible to perform a continuous monitoring of the liquid measurements even during the irradiation phase. Thus, it can operate not only as a pre-treatment detector but also as a continuous one.

Local Cancer Recurrence: The Realities, Challenges, and Opportunities for New Therapies

Locoregional recurrence negatively impacts both long-term survival and quality of life for several malignancies. For appropriate-risk patients with an isolated, resectable, local recurrence, surgery represents the only potentially curative therapy. However, oncologic outcomes remain inferior for patients with locally recurrent disease even after macroscopically complete resection. Unfortunately, these operations are often extensive, with significant perioperative morbidity and mortality. This review highlights selected malignancies (mesothelioma, sarcoma, lung cancer, breast cancer, rectal cancer, and peritoneal surface malignancies) in which surgical resection is a key treatment modality and local recurrence plays a significant role in overall oncologic outcome with regard to survival and quality of life. For each type of cancer, the current, state-of-the-art treatment strategies and their outcomes are assessed. The need for additional therapeutic options is presented given the limitations of the current standard therapies. New and emerging treatment modalities, including polymer films and nanoparticles, are highlighted as potential future solutions for both prevention and treatment of locally recurrent cancers. Finally, the authors identify additional clinical and research opportunities and propose future research strategies based on the various patterns of local recurrence among the different cancers.

Intraoperative Electron Radiation Therapy Combined with External Beam Radiation Therapy after Gross Total Resection in Extremity Soft Tissue Sarcoma: A European Pooled Analysis

INTRODUCTION

We report a pooled analysis evaluating the combination of gross complete limb-sparing surgery, intraoperative electron radiation therapy (IOERT), and external beam radiation therapy (EBRT) in patients with extremity soft tissue sarcoma (STS).

METHODS

Individual data of 259 patients (median follow-up 63 months) with extremity STS from three European expert centers were pooled. Median age was 55 years and median tumor size was 8 cm. Eighty percent of patients presented with primary disease, mainly located in the lower limb (81%). Union for International Cancer Control 7th edition stage at presentation was as follows: stage I: 9%; stage II: 47%; stage III: 39%; stage IV: 5%. Most patients showed high-grade lesions (91%), predominantly liposarcoma (31%). Median IOERT dose was 12 Gy, preceeded (17%) or followed (83%) by EBRT, with a median dose of 45 Gy.

RESULTS

Surgery resulted in R0 resections in 71% of patients and R1 resections in 29% of patients. The 5-year local control (LC) rate was 86%, and significant factors in univariate analysis were disease status and resection margin. Only margin remained significant in multivariate analysis. The 5-year distant control rate was 69%, and significant factors in univariate analysis were histology, grading, resection margin, and metastases prior to/at IOERT. Only grading and metastases remained significant in multivariate analysis. Actuarial 5-year rates of freedom from treatment failure and OS were 61% and 78%, respectively. Significant factors for OS were grading and metastases prior to/at IOERT (univariate, multivariate). Limb preservation and good functional outcome were achieved in 95% and 81% of patients.

CONCLUSIONS

Our pooled analysis confirmed prior reports of encouraging LC and survival, with excellent rates of preserved limb function with this treatment approach. Resection margin remained the most important factor for LC, while grading and metastases prior to/at IOERT mainly predicted survival.

System and path planning algorithm for low-kV X-ray free-form surface irradiation

OBJECTIVE

Intraoperative radiotherapy (IORT) after surgical resection using a low-kV-X-ray source is a proven method used in cancer treatment. However, the shape and size of the targeted surface area are limited to the size of the available applicators. This can lead to nonconformal and therefore suboptimal treatment for many patients.

METHODS

A system is proposed comprising an X-ray source with an applicator for surface irradiation mounted on a robotic arm. This is controlled by an algorithm designed for planning the required continuous path, enabling irradiation of any desired shape with a controlled dose distribution.

RESULTS

The system is shown to be capable of irradiating areas composed of rectangles on a flat surface with a homogeneity index of less than 7% inside the targeted area.

CONCLUSION

The presented results demonstrate the potential of the proposed setup to eliminate the current limitations, leading to better treatment of patients.

Abscopal, immunological effects of radiotherapy: Narrowing the gap between clinical and preclinical experiences

Radiotherapy-despite being a local therapy that meanwhile is characterized by an impressively high degree of spatial accuracy-can stimulate systemic phenomena which occasionally lead to regression and rejection of non-irradiated, distant tumor lesions. These abscopal effects of local irradiation have been observed in sporadic clinical case reports since the beginning of the 20th century, and extensive preclinical work has contributed to identify systemic anti-tumor immune responses as the underlying driving forces. Although abscopal tumor regression still remains a rare event in the radiotherapeutic routine, increasing numbers of cases are being reported, particularly since the clinical implementation of immune checkpoint inhibiting agents. Accordingly, interests to systematically exploit the therapeutic potential of radiotherapy-stimulated systemic responses are constantly growing. The present review briefly delineates the history of radiotherapy-induced abscopal effects and the activation of systemic anti-tumor immune responses by local irradiation. We discuss preclinical and clinical reports with specific focus on the corresponding controversies, and we propose issues that should be addressed in the future in order to narrow the gap between preclinical knowledge and clinical experiences.

Retroperitoneal or mesenteric primary liposarcoma: clinical and prognostic evaluations on five cases

BACKGROUND

Retroperitoneal or mesenteric primary liposarcoma is a malignant neoplasia whose prognosis depends on the biological variants, the radical resection surgery and the histological subtypes, as well as on local and remote recurrences. Liposarcoma is the most common variant of this tumour among tumours of soft retroperitoneal tissue. The purpose of this study is to evaluate whether the treatment of this disease, carried out at the Ivrea Hospital for urgent reasons, may be considered in line with the experience of high-volume Centres.

PATIENTS AND METHODS

Between 1982 and 2016 five patients were hospitalized with a diagnosis of acute abdomen due to retroperitoneal or mesenteric primary liposarcoma: one myxoid of the mesentery, one well-differentiated of lesser epiploon, one well-differentiated of mesentery, and two dedifferentiates of the retroperitoneum.

RESULTS

The five patients, all males, had a average age of 59 years (range 48-86) and were all subjected to general anaesthesia and open technique for total tumour removal. Only the patient with the myxoid liposarcoma had two recurrences. All are alive and healthy after a follow-up of 177 months (range 9-420).

CONCLUSION

These tumours should be removed radically, if necessary in conjunction with contiguous organs. Rarity and therapeutic complexity require a treatment, sometimes even multimodal, in highvolume centres. Patients admitted in General Surgery Unit for unpostponable urgency should be operated by surgeons experienced in the treatment of abdominal disease to achieve survival results in line to those achievable in Hub Centres.

Prediction of clinical outcome and survival in soft-tissue sarcoma using a ten-lncRNA signature

The prognostic value of long non-coding RNAs (lncRNAs) in patients with soft-tissue sarcoma has rarely been unraveled. The aim of the study was to find a lncRNA signature to predict the clinical outcome and survival in soft-tissue sarcoma based on the high-throughput RNA-seq data from The Cancer Genome Atlas (TCGA) database. The lncRNAs which closely correlated with overall survival in 258 soft-tissue sarcoma patients were identified with Cox proportional regression model. Ten lncRNAs, including RP11-560J1.2, AP001432.14, RP4-665J23.1, LINC00680, AC006129.2, RP11-230G5.2, BACH1-IT2, RP11-274B21.9, RP11-504A18.1 and RP11-713P17.3, were selected to calculate a risk score. The risk score could effectively predict patients’ outcome, such as the status of mitotic count of tumor cells, person neoplasm cancer and residual tumor. More inspiringly, the risk score generated from the 10-lncRNA signature was an independent prognostic indicator for soft-tissue sarcoma patients. Overall, this 10-lncRNA signature gains the potential as an effective prognostic tool for soft-tissue sarcoma as part of the integrated clinical RNA-seq program.