Intraoperative radiotherapy in gynaecological and genito-urinary malignancies: focus on endometrial, cervical, renal, bladder and prostate cancers

Extending deterministic transport capabilities for very-high and ultra-high energy electron beams

Focused Very-High Energy Electron (VHEE, 50-300 MeV) and Ultra-High Energy Electron (UHEE, > 300 MeV) beams can accurately target both large and deeply seated human tumors with high sparing properties, while avoiding the spatial requirements and cost of proton and heavy ion facilities. Advanced testing phases are underway at the CLEAR facilities at CERN (Switzerland), NLCTA at Stanford (USA), and SPARC at INFN (Italy), aiming to accelerate the transition to clinical application. Currently, Monte Carlo (MC) transport is the sole paradigm supporting preclinical trials and imminent clinical deployment. In this paper, we propose an alternative: the first extension of the nuclear-reactor deterministic chain NJOY-DRAGON for VHEE and UHEE applications. We have extended the Boltzmann-Fokker-Planck (BFP) multigroup formalism and validated it using standard radio-oncology benchmarks, complex assemblies with a wide range of atomic numbers, and comprehensive irradiation of the entire periodic table. We report that [Formula: see text] of water voxels exhibit a BFP-MC deviation below [Formula: see text] for electron energies under [Formula: see text]. Additionally, we demonstrate that at least [Formula: see text] of voxels of bone, lung, adipose tissue, muscle, soft tissue, tumor, steel, and aluminum meet the same criterion between [Formula: see text] and [Formula: see text]. For water, the thorax, and the breast intra-operative benchmark, typical average BFP-MC deviations of [Formula: see text] and [Formula: see text] were observed at [Formula: see text] and [Formula: see text], respectively. By irradiating the entire periodic table, we observed similar performance between lithium ([Formula: see text]) and cerium ([Formula: see text]). Deficiencies observed between praseodymium ([Formula: see text]) and einsteinium ([Formula: see text]) have been reported, analyzed, and quantified, offering critical insights for the ongoing development of the Evaluated Nuclear Data File mode in NJOY.

Calculated and measured radiation dose for the low energy xoft axxent eBT X-ray source

PURPOSE

In this study, it was aimed to evaluate the functionality to deliver different prescription dose except 20 Gy for the Xoft Axxent Ebt (electronic Brachytherapy) system and analyzing the system in terms of radiation dosimetry in water and 0.9% isotonic Sodium Chloride (NaCl) solution.

MATERIALS AND METHODS

In the Xoft Axxent eBT, different prescription dose in single fraction were calculated for different balloon applicator volumes based on source position and irradiation times. EBT-XD Gafchromic film was calibrated at 6MV photon energy. A balloon applicator filled with 0.9% isotonic NaCl solution was used to deliver a radiation dose of 20 Gy, 16 Gy, 10 Gy on the applicator surface. Then the balloon applicator was filled with water and the same measurements were repeated. Finally, the balloon applicator was irradiated by positioning it at different distances in the water phantom to simulate the isodose contour.

RESULTS

At the time the balloon applicator was filled with water and 0,9% NaCl solution, the difference between the planned dose and the absorbed dose was ~ 2% vs. 15% for 30 cc, ~ 5% vs. 14% for 35 cc and ~ 3,5% vs. 10% for 40 cc respectively. Finally, the absorbed dose at a distance of 1 cm from the applicator surface was measured as 9.63 Gy.

CONCLUSION

In this study, it was showed that different prescription dose could be possible to deliver in the Xoft Axxent eBT system based on the standard plan. In addition, the absorbed dose was higher than the planned dose depending on the effective atomic number of NaCl solution comparing to water due to photoelectric effect in low energy photons. By measuring the dose distributions at different distances from the balloon applicator surface, the absorbed dose in tissue equivalent medium was determined and the isodose contours characteristics was simulated.

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.

Effectiveness of intraoperative radiotherapy vs hypofractionated postmastectomy radiotherapy for early stage breast cancer: A protocol for systematic review and meta-analysis

BACKGROUND

Radiotherapy is one of the essential components of breast cancer treatment. It destroys the remaining cells in the chest area after breast cancer surgery and is useful for reducing the necessity of mastectomies. As a single dose of radiation at the time of breast conserving surgery, intraoperative radiotherapy delivers radiotherapy directly and accurately to the tumor itself or the tumor bed whilst delivering minimal dose to the surrounding normal tissues. Hypofractionated postmastectomy radiotherapy with shorter and more convenient hypofractionated dose schedules might help to treat more patients and reduce cost. We will conduct a comprehensive systematic review and meta-analysis to compare the effectiveness of these 2 therapies in the management of early stage breast cancer.

METHODS

Four English databases (PubMed, Embase, Cochrane Library, and Web of Science) and 3 Chinese databases (China National Knowledge Infrastructure, China Science and Technology Journal Database, and Chinese Biomedical Literature Database) will be searched from inception of databases to December 2020 without language limitation. Two reviewers will independently conduct selection of studies, data extraction and management, and assessment of risk of bias. Any disagreement will be resolved by the third reviewer. Review Manager 5.3 (The Cochrane Collaboration, Software Update, Oxford, UK) will be used for data synthesis. Cochrane risk of bias assessment tool will be used to assess the risk of bias.

RESULTS

This study will provide a systematic synthesis of current published data to compare the effectiveness of intraoperative radiotherapy vs hypofractionated postmastectomy radiotherapy for early stage breast cancer.

CONCLUSIONS

This systematic review and meta-analysis will provide clinical evidence for the effectiveness of intraoperative radiotherapy vs hypofractionated postmastectomy radiotherapy for early stage breast cancer, and inform our understanding of the value of intraoperative radiotherapy and hypofractionated postmastectomy radiotherapy for early stage breast cancer.

STUDY REGISTRATION NUMBER

INPLASY2020110115.

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.

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.

American Brachytherapy Society working group report on the patterns of care and a literature review of reirradiation for gynecologic cancers

PURPOSE

Recurrences of previously irradiated gynecological malignancies are uncommon. Standardized management of these cases is not well established. We aim to provide an in-depth literature review and present current practice patterns among an international group of experienced practitioners in the reirradiation setting of gynecologic cancers.

METHODS AND MATERIALS

An extensive literature search was performed and 35 articles were selected based on preset criteria. A 20-question online survey of 10 experts regarding their retreatment practices was also conducted.

RESULTS

The reviewed publications include a diverse group of patients, multiple treatment techniques, a range of total doses, local control, overall survival, and toxicity outcomes. Overall, local control ranged from 44% to 88% over 1-5 years with OS in the range of 39.5-82% at 2-5 years. Late G3-4 toxicity varied very broadly from 0% to 42.9%, with most papers reporting serious toxicities greater than 15%. The most common reirradiation technique utilized was brachytherapy. Some low-dose-rate data suggest improved outcomes with doses >50 Gy. The high-dose-rate data are more varied with some studies suggesting improved local control with doses >40 Gy. In general, a longer time interval between the first and second course of radiation as well as recurrences <2-4 cm tend to have improved outcomes.

CONCLUSIONS

Reirradiation with brachytherapy results in relatively reasonable local control and toxicities for women with recurrent gynecologic cancers. The appropriate dose for each case needs to be individualized given the heterogeneity of cases. Multidisciplinary management is critical to develop individualized plans and to clearly communicate potential side effects and expected treatment outcomes.

TAKE HOME MESSAGE

Reirradiation with brachytherapy is an acceptable effective organ preserving approach for recurrent gynecologic cancers with a reasonable local control and toxicity profile. Each case requires multidisciplinary management to develop an individualized approach. Monitoring for potential long-term toxicities is essential.

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.

Intraoperative radiation therapy in uterine cervical cancer: A review

Locally advanced uterine cervical cancer continues to present a high number of pelvic relapses. Intraoperative radiation therapy (IORT) allows a precise therapeutic intensification in the surgical area in cases in which removal of the tumour recurrence is feasible. At the same time, IORT excludes the radiosensitive organs from the field of irradiation. While the first gynecological IORT took place in 1905, procedures have been limited over the years and the series are retrospective, including few patients. At the same, time recurrences are located at different pelvic areas. Both heterogeneity and the long recruiting time make it difficult to correctly interpret the published results. Despite this, we have reviewed the most relevant publications. Some institutions indicated IORT as a boost on the surgical bed of the excised tumor recurrence. In others, IORT permits an extra radiation dose after radical surgery of the primary tumor, usually in stage IIB. Most studies conclude that the addition of IORT increases the local control but probably with little impact on survival. On the other hand, there is a controversy in the indication of IORT in surgically resectable primary tumours. No clear advantage over the usual scheme of chemoradiation and brachytherapy has been detected. Randomized studies that allow a breakthrough in the conclusions are highly unlikely to be performed in this area.

Experimental study of pelvic perioperative brachytherapy with iodine 125 seeds (I-125) in an animal model

Purpose

The aim of this study is to investigate the feasibility of perioperative I-125 low-dose-rate brachytherapy mesh implantation in pelvic locations in an animal model, before applying it clinically.

Material and methods

The animal model was the Romanov adult ewe. Non-radioactive dummy I-125 seeds were implanted by laparotomy in the pelvic area. Forty-five dummy seeds were placed on a 10 cm² polyglactin mesh to obtain a dose of 160 Gy at 5 mm from the center of each seed. Three CT scans were performed at day 15, day 70, and day 180 after surgery to check the positioning of the mesh for eventual seed migration according to bony landmarks and to perform a 3D theoretical dosimetric study. The experimental study design was based on Simon’s minimax plan with a preliminary analysis of 10 ewes to validate the protocol and a second series of 7 ewes.

Results

After the first step, 9 of 10 ewes were investigated. For 8 of 9 animals, the 160 Gy isodose line volume was within 10%, showing feasibility of the procedure and allowing 7 more to be added. At the end of the study, 16 of 17 animals were examined. No seeds loss was observed. The volume difference of the 160 Gy isodose line was within 10% in 13 of 16 ewes between the three CT scans. Twelve out of 16 had a coordinate deviation less than or equal to 10 mm on the three axes between the first and the third scans.

Conclusions

These results show the technical feasibility of the pelvic mesh implantation in ewes. A phase I study for patients with locally advanced or recurrent pelvic tumors amenable to surgery, in combination with surgical resection should be possible.

The New Age of -omics in Urothelial Cancer - Re-wording Its Diagnosis and Treatment

Unmet needs in urothelial cancer management represent an important challenge in our effort to improve long-term overall and disease-free survival rates with no significant compromise in quality of life. Radical cystectomy with pelvic lymph node dissection is the standard for the management of muscle-invasive, non-metastatic cancers. In spite of a 90% local disease control, up to 50% of patients ultimately die of distant metastasis. Bladder preservation using chemo-radiation is an acceptable alternative, but optimal patient selection remains elusive. Recent research is focused on the employment of tailored-made strategies in urothelial cancer exploiting the potential of theranostics in patient selection for specific therapies. Herein, we review the current knowledge on molecular theranostics in urothelial cancer and we suggest that this is the time to move toward imaging theranostics, if tailored-made disease management and patient stratification is envisaged.

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Urothelial cancer management represents an important challenge.

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Optimum patient stratification and tailored-made theranostics remain elusive.

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Imaging theranostics is envisaged as a cancer roadmap.

Re-irradiation of cervical and endometrial cancer

PURPOSE OF REVIEW

Re-irradiation historically has been associated with unacceptable toxicity and limited benefit. Recent advances in radiotherapy can change the treatment paradigm to provide new salvage treatments for recurrences of cervical and endometrial cancer.

RECENT FINDINGS

Image-guided brachytherapy is an effective method for salvaging central pelvic recurrence, although it has resulted in 20-25% severe late toxicity. Pelvic sidewall disease is not accessible to brachytherapy, so a combined modality approach with radical surgery and intraoperative radiotherapy is an alternative approach. Stereotactic body radiotherapy (SBRT) now provides the option of radical re-irradiation with local control rates of 50-80% and a low incidence of severe late complications.

SUMMARY

Initial outcomes using SBRT and image-guided brachytherapy for re-irradiation of gynaecological cancer are encouraging. There has been good local control and acceptable toxicity. Further, large-scale studies are required to define optimal target doses and OAR limits.