Analysis of Radiation Dose/Volume Effect Relationship for Anorectal Morbidity in Children Treated for Pelvic Malignancies

Dose-Volume Constraints fOr oRganS At risk In Radiotherapy (CORSAIR): An "All-in-One" Multicenter-Multidisciplinary Practical Summary

BACKGROUND

The safe use of radiotherapy (RT) requires compliance with dose/volume constraints (DVCs) for organs at risk (OaRs). However, the available recommendations are sometimes conflicting and scattered across a number of different documents. Therefore, the aim of this work is to provide, in a single document, practical indications on DVCs for OaRs in external beam RT available in the literature.

MATERIAL AND METHODS

A multidisciplinary team collected bibliographic information on the anatomical definition of OaRs, on the imaging methods needed for their definition, and on DVCs in general and in specific settings (curative RT of Hodgkin's lymphomas, postoperative RT of breast tumors, curative RT of pediatric cancers, stereotactic ablative RT of ventricular arrythmia). The information provided in terms of DVCs was graded based on levels of evidence.

RESULTS

Over 650 papers/documents/websites were examined. The search results, together with the levels of evidence, are presented in tabular form.

CONCLUSIONS

A working tool, based on collected guidelines on DVCs in different settings, is provided to help in daily clinical practice of RT departments. This could be a first step for further optimizations.

Long-term urological complications after conservative local treatment (surgery and brachytherapy) in children with bladder-prostate rhabdomyosarcoma: A single-team experience

BACKGROUND

Outcome of children with bladder-prostate rhabdomyosarcoma (RMS) has improved with multimodal therapies, including surgery and/or radiotherapy for local treatment. Our aim was to report long-term urological complications after a conservative approach combining conservative surgery and brachytherapy.

PATIENTS AND METHODS

Eighty-six patients, free of disease, were retrospectively reviewed. Symptoms related to urinary tract obstruction, incontinence, infection, and lithiasis were reported and graded according to the Common Terminology Criteria for Adverse Events (CTCAE) classification. Only symptomatic patients underwent urodynamic studies. Risk factors for complications were analyzed.

RESULTS

There were 76 males and 10 females. The median follow-up was 6.3 years (18 months to 24 years). Complications occurred after a median follow-up of 5 years (0-21). Twenty-two patients (26%) had long-term urological complications. Urinary tract obstruction was found in 15 patients (17%) and urinary incontinence in 14 patients (16%). Recurrent urinary tract infection occurred in four patients and urinary lithiasis in four (5%). The underlying physiopathology included bladder dysfunction in 15 patients (17%), urethral stenosis in six (7%), and ureterovesical junction stenosis in five (6%). On univariate analysis, posterior bladder wall dissection (p = .001), bladder neck trigone dissection (p = .010), and partial prostatectomy (p = .023) were significantly associated with an increased risk of bladder dysfunction; on multivariate analysis, only age ≤2 years (p = .028) at operation and posterior bladder wall dissection (p = .006) were found to be significant.

CONCLUSION

The conservative surgical approach combined with brachytherapy for bladder-prostate RMS leads to long-term urological complications in 26% of survivors. Optimizing brachytherapy doses for young children and establishing a clear and long-term follow-up protocol could help to reduce these complications.

Brachytherapy for Pediatric Patients at Gustave Roussy Cancer Campus: A Model of International Cooperation for Highly Specialized Treatments

PURPOSE

Childhood cancer is rare, and treatment is frequently associated with long-term morbidity. Disparities in survival and long-term side effects encourage the establishment of networks to increase access to complex organ-conservative strategies, such as brachytherapy. We report our experience of an international cooperation model in childhood cancers.

METHODS AND MATERIALS

We examined the outcome of all children referred to our center from national or international networks to be treated according to a multimodal organ-conservative approach, including brachytherapy.

RESULTS

We identified 305 patients whose median age at diagnosis was 2.2 years (range, 1.4 months to 17.2 years). Among these patients, 99 (32.4%) were treated between 2015 and 2020; 172 (56.4%) were referred from national centers; and 133 (43.6%) were international patients from 31 countries (mainly Europe). Also, 263 patients were referred for primary treatment and 42 patients were referred for salvage treatment. Genitourinary tumors were the most frequent sites, with 56.4% bladder/prostate rhabdomyosarcoma and 28.5% gynecologic tumors. In addition to brachytherapy, local treatment consisted of partial tumor resection in 207 patients (67.9%), and 39 patients (13%) had additional external radiation therapy. Median follow-up was 58 months (range, 1 month to 48 years), 93 months for national patients, and 37 months for international patients (P < .0001). Five-year local control, disease-free survival, and overall survival rates were 90.8% (95% confidence interval [CI], 87.3%-94.4%), 84.4% (95% CI, 80.1%-89.0%), and 93.3% (95% CI, 90.1%-96.5%), respectively. Patients referred for salvage treatment had poorer disease-free survival (P < .01). Implementation of image guided pulse-dose-rate brachytherapy was associated with better local control among patients with rhabdomyosarcoma referred for primary treatment (hazard ratio, 9.72; 95% CI, 1.24-71.0). At last follow-up, 16.7% patients had long-term severe treatment-related complications, and 2 patients (0.7%) had developed second malignancy.

CONCLUSIONS

This retrospective series shows the feasibility of a multinational referral network for brachytherapy allowing high patient numbers in rare pediatric cancers. High local control probability and acceptable late severe complication probability could be achieved despite very challenging situations. This cooperation model could serve as a basis for generating international reference networks for high-tech radiation such as brachytherapy to increase treatment care opportunities and cure probability.

Radiotherapy-Induced Digestive Injury: Diagnosis, Treatment and Mechanisms

Radiotherapy is one of the main therapeutic methods for treating cancer. The digestive system consists of the gastrointestinal tract and the accessory organs of digestion (the tongue, salivary glands, pancreas, liver and gallbladder). The digestive system is easily impaired during radiotherapy, especially in thoracic and abdominal radiotherapy. In this review, we introduce the physical classification, basic pathogenesis, clinical characteristics, predictive/diagnostic factors, and possible treatment targets of radiotherapy-induced digestive injury. Radiotherapy-induced digestive injury complies with the dose-volume effect and has a radiation-based organ correlation. Computed tomography (CT), MRI (magnetic resonance imaging), ultrasound (US) and endoscopy can help diagnose and evaluate the radiation-induced lesion level. The latest treatment approaches include improvement in radiotherapy (such as shielding, hydrogel spacers and dose distribution), stem cell transplantation and drug administration. Gut microbiota modulation may become a novel approach to relieving radiogenic gastrointestinal syndrome. Finally, we summarized the possible mechanisms involved in treatment, but they remain varied. Radionuclide-labeled targeting molecules (RLTMs) are promising for more precise radiotherapy. These advances contribute to our understanding of the assessment and treatment of radiation-induced digestive injury.

Use of an intravaginal spacer in young girls treated with brachytherapy for bladder neck rhabdomyosarcoma: Dosimetric impact for organs at risk sparing and acute tolerance

PURPOSE

Interstitial brachytherapy is indicated as part of a conservative strategy for children with bladder and/or prostate rhabdomyosarcoma (RMS), providing high local control probability with acceptable functional results. Vaginal and/or rectal complications were however reported, due to the close proximity to the implanted volume. We investigated the dosimetric impact of a vaginal spacer in terms of rectal and vaginal doses.

METHODS AND PATIENTS

Medical records of 12 consecutive female patients with bladder neck RMS, median age 32 months (range: 1.3-6 years), were reviewed. Five patients were treated prior to 2017 without a vaginal spacer and seven patients treated after 2017 had their brachytherapy delivered with a vaginal spacer placed at time of implant.

RESULTS

Minimal doses delivered to the most exposed 2cm³, 1cm³, and 0.5cm³ of the rectum were all statistically significantly lower among patients treated with a vaginal spacer, as compared to those treated without a spacer. Median rectal D2cm³ was 22Gy_EQD2 versus 38Gy_EQD2 (P=0.02), D1cm³ was 29Gy_EQD2 versus 51Gy_EQD2 (P=0.013), and D0.5cm³ was 32Gy_EQD2 versus 61Gy_EQD2 (P=0.017), with and without the vaginal spacer, respectively. The posterior vaginal wall D0.5cm³ dose was also significantly decreased, with median D0.5cm³ of 92Gy_EQD2 versus 54Gy_EQD2 (P<0.0001), with and without the spacer, respectively. Acute tolerance was excellent in all patients, with no need for replanning and no acute complication.

CONCLUSIONS

The use of vaginal spacers in brachytherapy of female pediatric patients with bladder neck RMS resulted in significantly decreased doses to the rectum and the posterior vaginal wall. Though the clinical impact of such dose reduction remains undemonstrated, routine utilization of a vaginal spacer could be a method to decrease long-term morbidity in these patients.

New aspects and innovations in the local treatment of renal and urogenital pediatric tumors

Local treatment plays a key role for patients' outcome in tumors of the urogenital tract in children. Despite a great variety of different etiologies, the specific localization of pediatric urogenital tumors renders several characteristic demands to the treating personnel. Surgery and radiotherapy are the main elements of local treatment in this group of neoplasms. Numerous new guidelines and innovative technical developments of surgery and radiotherapy have recently been integrated into treatment concepts for pediatric urogenital tumors. Due to the broadness of the field it is not possible to give a full overview over all aspects. Therefore, this article highlights the most important innovations and new guidelines of surgery and radiotherapy of pediatric urogenital tumors.