Practical Aspects of Pediatric Proton Radiation Therapy

Inhalation anesthesia without any intravenous management for pediatric proton beam therapy

INTRODUCTION

Proton beam therapy is an oncological treatment, argued to be an appropriate tumor irradiation technique for childhood solid tumors. Due to its duration and the need for immobility, many children require anesthesia for proton therapy sessions. As not many centers in the world provide this therapy, there is little published research about pediatric anesthesia for these cases, and the available data suggest a preference for intravenous anesthesia or combined intravenous and inhalation anesthesia. We conducted this study with the aim of describing and analyzing the inhalation anesthetic management of children undergoing proton therapy at our medical center, comparing our results with studies that have followed different anesthetic protocols.

METHODS

We reviewed two major databases (Web of Science and Scopus) to find papers that had addressed, to date, anesthesia for pediatric proton therapy. To describe our anesthetic management, we included all pediatric patients treated with proton therapy under anesthesia in our center between June 2020 and August 2021. The characteristics of the patients, their diagnoses, treatments, airway management, drugs administered, duration of induction, and recovery from anesthesia, and adverse effects where all recorded. All anesthesiologists followed a strict anesthetic protocol based only on inhalational anesthesia with sevoflurane delivered via laryngeal mask airway.

RESULTS

Of the total of 1082 papers found in Web of Science and Scopus on pediatric proton therapy, 11 have addressed its anesthetic management, using intravenous or combined intravenous and inhalation anesthesia. Between June 2020 and August 2021, 31 children were anesthetized in our center to receive proton therapy under inhalational anesthesia (total number of sessions: 873). The mean anesthesia induction time was 4.1 min (SD = 0.7, 95% CI [3.9, 4.4]). The mean anesthesia recovery time was 13.8 min (SD = 4.1, 95% CI [12.3, 15.3]). The percentage of non-serious adverse effects was 0.7% (Clopper-Pearson 95% CI [0.3, 1.5]). The percentage of serious adverse effects was 0.1% (Clopper-Pearson 95% CI [0, 0.6]), without statistically significant difference with other published works with different anesthetic approaches.

CONCLUSION

Inhalation anesthesia without any intravenous management for pediatric proton therapy is, in our experience, an effective technique with a complication rate similar to other anesthetic approaches.

American Brachytherapy Society (ABS) consensus statement for soft-tissue sarcoma brachytherapy

PURPOSE

Growing data supports the role of radiation therapy in the treatment of soft tissue sarcoma (STS). Brachytherapy has been used for decades in the management of STS and can be utilized as monotherapy or as a boost to external beam radiation. We present updated guidelines from the American Brachytherapy Society regarding the utilization of brachytherapy in the management of STS.

METHODS AND MATERIALS

Members of the American Brachytherapy Society with expertise in STS and STS brachytherapy created an updated clinical practice guideline including step-by-step details for performing STS brachytherapy based on a literature review and clinical experience.

RESULTS

Brachytherapy monotherapy should be considered for lower-recurrence risk patients or after a local recurrence following previous external beam radiation; a brachytherapy boost can be considered in higher-risk patents meeting implant criteria. Multiple dose/fractionation regimens are available, with determination based on tumor location and treatment intent. Techniques to limit wound complications are based on the type of wound closure; wound complication can be mitigated with a delay in the start of brachytherapy with immediate wound closure or by utilizing a staged reconstruction technique, which allows an earlier treatment start with a delayed wound closure.

CONCLUSIONS

These updated guidelines provide clinicians with data on indications for STS brachytherapy as well as guidelines on how to perform and deliver high quality STS brachytherapy safely with minimal toxicity.

Practice Patterns Among Radiation Oncologists Treating Pediatric Patients With Proton Craniospinal Irradiation

PURPOSE

Craniospinal irradiation (CSI) is an important component of therapy for many pediatric central nervous system malignancies. Proton therapy is increasingly available and used for minimizing radiation exposure to normal tissues. The absence of an exit dose with proton therapy mandates decisions regarding coverage of the vertebral bodies (VB) in non-skeletally mature patients. Although the contents within the thecal sac represent the true clinical target volume (CTV), some physicians target the entire VB in growing children because of concerns over asymmetrical growth. This study aims to assess current practice patterns regarding VB coverage for pediatric patients undergoing CSI.

METHODS AND MATERIALS

Pediatric radiation oncologists were identified from the Particle Therapy Co-Operative Group pediatric subcommittee membership or affiliation with US proton centers. Potential participants were contacted by e-mail with a link to an institutional review board-approved, anonymized web-based survey distributed in June 2017 with follow-up in October 2017. The survey used skip logic and included up to 11 questions regarding practice patterns.

RESULTS

Thirty-three physicians responded to the survey (39%), 5 of which were excluded for lack of recent pediatric proton CSI experience. Of the 28 included responses, 23 physicians sometimes treat the entire VB and 5 physicians report always treating the entire VB. Most common responses regarding anterior CTV expansion for uncertainty were no expansion (n = 9) and 3 to 4 mm (n = 8). Most physicians modify the anterior CTV margin to protect normal structures, most commonly esophagus (n = 15), thyroid (n = 6), heart (n = 5), bowel (n = 4), and pharynx (n = 2).

CONCLUSIONS

Vertebral body coverage in proton CSI varies among radiation oncologists in respect to target delineation, CTV expansions, and modifications for organs at risk. These data suggest the radiation oncology community may benefit from a standardized approach to pediatric proton-based CSI.

125 I interstitial brachytherapy in management of pediatric skull base tumors

BACKGROUND

The purpose of this study was to present our preliminary assessment of the safety and efficacy of ¹²⁵ I interstitial brachytherapy (IBT) in the management of pediatric skull base tumors.

METHODS

Thirty pediatric patients with skull base tumors treated with ¹²⁵ I IBT from April 2007 to May 2017 were included in this study. The probabilities of local control (LC) and overall survival (OS) were calculated by the Kaplan-Meier method.

RESULTS

The one- and two-year LC rates were 96.7% and 74.8%, respectively. The one- and two-year OS rates were 93.3% and 72.2%, respectively. No severe acute toxicity was observed. Severe late toxicities were observed in one (3.33%) of 30 patients.

CONCLUSION

¹²⁵ I IBT is effective and safe in the management of pediatric skull base tumors, with satisfactory cosmetic and functional outcomes.

Clinical Profile of Pediatric Oncology Patients Treated by External Beam Radiotherapy: An Institutional Experience

Introduction:

Pediatric tumors are a heterogeneous group of malignant conditions requiring multimodal treatment, and management of such cases is at time challenging. We present the clinical profile of pediatric cancer patients who received radiation, either alone or as adjuvant to surgery and chemotherapy; in prophylactic, radical or palliative clinical setting.

Aim:

This study was envisaged to review our experience of pediatric oncology cases, their clinical and morphological profile, dosage schedule of radiotherapy, and the therapy induced complications.

Settings and Design:

This was a retrospective, observational study carried out in an apex tertiary care cancer institute of government set-up in a developing country.

Materials and Methods:

The treatment charts and clinical summary of patients who had received radiation over the last 5 years period were retrieved and perused. Various clinical and pathological parameters were studied and inferences drawn.

Results:

A total of 50 patients got radiation over 5 year study-period, including 37 male and 13 female patients. The commonest age group of presentation was 8-12 years followed by 13-16 years. The mean age of presentation was 9.3 years. The most common diagnosis was hematological malignancies followed by CNS tumors with 21 and 13 patients respectively. Overall the most common indication of RT was in adjuvant setting after surgery as the definitive management, where 24 patients were irradiated; and the next common indication was prophylactic cranial irradiation in 14 patients of childhood leukemias. 10 patients tolerated treatment with Grade 1 site-specific or systemic toxicities while 7 patients developed Grade 2 and more systemic toxicities. 9 patients received craniospinal irradiation, common indications being medulloblastoma and Atypical teratoma rhabdoid tumor (ATRT). 3 patients received concurrent chemotherapy with weekly Inj Vincristine. 17 patients required sedation or short general anaesthesia for radiation planning and execution.

Conclusion:

External beam Radiotherapy constitutes an important component of management of pediatric cancers. One should be judicious in Radiotherapy planning, execution and monitoring acute and delayed toxicities.

Clinical Benefits of Proton Beam Therapy for Tumors of the Skull Base

BACKGROUND

The unique radiobiological properties of protons have been understood for many years. In addition, many of the clinical benefits of radiotherapy were first noted in tumors involving the skull base. More public attention has been given to proton beam therapy due to the increasing number of centers now in operation or in the planning stages for offering this treatment option.

METHODS

We reviewed the physical properties of protons and the clinical studies performed to justify their use in the management of skull-base tumors and determine the benefits of proton beam therapy.

RESULTS

Published reports suggest a benefit to proton beam therapy for use in tumors of the skull base, including craniopharyngiomas, chordomas, skull-base sarcomas, and unresectable meningiomas.

CONCLUSIONS

Use of proton beam therapy may be beneficial in select patients. Surgical and medical oncologists should have a general understanding of such cases to facilitate their appropriate referral.

Radiation Oncology Practice: Adjusting to a New Reimbursement Model

PURPOSE

Use of hypofractionation is increasing in radiation oncology because of several factors. The effects of increasing hypofractionation use on departments and staff currently based on fee-for-service models are not well studied.

METHODS

We modeled the effects of moving to hypofractionation for prostate, breast, and lung cancer and palliative treatments in a typical-sized hospital-based radiation oncology department. Year 2015 relative value unit (RVU) data were used to determine changes in reimbursement. The change in number of fractions was used to model the effects on machine volume, staff time, and workforce predictions.

RESULTS

The per-case marginal reduction in technical revenue was $1,777, $4,297, $9,041, and $9,498 for palliative and breast, prostate, and lung cancer cases, respectively. The physician reduction per case in RVUs was 5.22, 10.44, 43.02, and 43.02 respectively. A department could anticipate an annual reduction in technical revenue of $540,661 and a reduction in workflow of approximately five patients or 1 to 1.5 hours per day from a hypofractionation rate of 40%.

CONCLUSION

The move to hypofractionation in the United States will lead to increased pressures on departments to address budget shortfalls resulting from the decrease in per-patient revenue. This may be done through a combination of an increase in patient volume, recognition of the increased skill sets required to deliver hypofractionated radiotherapy, delay in capital purchases, and/or reduction in staff. In a value-based environment, these evolutions should improve the value proposition of radiation oncology over a fee-for-service model.