Are intraoral stents effective in reducing oral toxicities caused by radiotherapy? A systematic review and meta-analysis

Dosimetric benefits of customised mouth-bite for head neck cancer patients undergoing modern proton therapy - An audit

Background and aims

Proton therapy (PRT) for Head Neck Cancer (HNC), in view of the Bragg peak, spares critical structures like oral mucosa better than IMRT. In PRT, mouth-bites, besides immobilising and separating mucosal surfaces, may also negate the end-of-range effect. We retrospectively analysed the details and dosimetric impact of mouth-bites in PRT for HNC.

Materials and methods

The data of consecutive HNC patients treated with IMPT from May 2020 to August 2022 were studied retrospectively. Details of the mouth-bite used, compliance and resultant mucosal separation were noted. Further analysis, restricted to previously unirradiated patients, comprised volumetric dosimetric data pertaining to the mouth-bite and distal mucosal surfaces. High LET zones, corresponding to 6-12 keV/micron, for mouth-bite doses above 30 Gy, were recalculated from existing plans.

Results

A mouth-bite was used in 69 of 80 consecutively treated patients, ranging from 8 to 42 mm in thickness, and 12 to 52 mm in the resultant mucosal sparing. In 42 patients in whom the mouth-bite V 32 Gy was > 0, median Dmean, absolute V32, V39, V50 and V60 GyE (Gray Equivalent) of the mouth bite was 35.65 GyE (Range: 2.65 - 60 GyE), 10 cc (Range: 0.1 - 32 cc), 7.6 cc (Range: 0.1 - 30.8 cc), 5.7 cc (Range: 0.2 - 29.2 cc) and 1.45 cc (Range: 0.2 - 18.1 cc) respectively, all significantly more than the spared adjacent mucosal surface. In absence of a mouth-bite, the spared mucosa would have at least partially received the high dose received by the mouth-bite. High LET zones were noted in 12 of 48 mouth-bites.

Conclusion

In PRT for HNC, mouth-bites play a vital role in improving the sparing of mucosa outside the target.

Systemic sequelae and craniofacial development in survivors of pediatric rhabdomyosarcoma

INTRODUCTION

The aim of this study was to evaluate the systemic sequelae, as well as the dental and craniofacial development, of patients with rhabdomyosarcoma in relation to the treatment received and clinical-pathological variables.

MATERIALS AND METHODS

A retrospective cross-sectional study was performed. All individuals diagnosed with RMS between 1990 and 2022 were considered eligible. Cases who survived the primary tumor were included. Data were collected from medical records, and patients were called for clinical and radiographic examinations.

RESULTS

Thirty-eight patients were assessed, with a mean disease-free survival of 216.68 months (±84.99). The primary location of the tumor was mainly the head and neck region (57.9 %). All patients received chemotherapy, and 30 (78.9 %) also underwent radiotherapy. The most frequently observed sequela was sensory impairment, which was significantly associated with tumors in the head and neck (p < 0.05), as well as with the use of radiotherapy (p = 0.034). Root formation failure was observed in 60 % of cases, microdontia in 50 %, and delayed tooth eruption in 40 %. A convex profile was predominant (80 %), along with maxillary (50 %) and mandibular (80 %) retrusion and a skeletal class II diagnosis (60 %).

CONCLUSIONS

Late systemic, dental, and craniofacial developmental sequelae are observed in pediatric rhabdomyosarcoma survivors, especially in patients who underwent radiotherapy in the head and neck region. Younger individuals at the time of treatment are at greater risk of late sequelae.

3D printing technology to produce intraoral stents for head and neck radiotherapy: A scoping review

INTRODUCTION

Radiotherapy remains one of the main treatments for head and neck cancer; however, it is accompanied by acute and chronic adverse effects. Use of three-dimensional (3D) oral stents to modulate radiation intensity to specific target areas have been developed to minimize these adverse effects. This study aimed to present a scoping review of studies published on 3D printing of oral stents and their clinical applicability.

METHODS

MEDLINE/Pubmed, Scopus, Web of Science and CENTRAL Cochrane data bases were searched, studies selected, and data collected by three independent reviewers up to December 2022. The review was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-analysis-Extension for Scoping Reviews (PRISMA-ScR).

RESULTS

The search resulted in 404 studies and 5 articles fulfilled the eligibility criteria and were considered for this review. Three-dimensional printed intraoral stents were produced for 56 patients with indication for radiotherapy. 3D-printed stents were well-tolerated by all tested patients and demonstrated great reproducibility of maxillomandibular relation, required less time for production and lower cost to manufacture. Two studies showed great protection of healthy tissues with 3D-printed stents during radiotherapy.

CONCLUSIONS

Three-dimensional printing is promising for production of intraoral stents, however, more studies are needed to improve the technique and further investigate the safety and prevention of oral toxicities from radiotherapy.

Wearing individualized 3D printed oral stent to protect normal tissues in patients with nasopharyngeal carcinoma during radiotherapy

PURPOSE

To demonstrate a new individualized 3D printed oral stent in radiotherapy of nasopharyngeal carcinoma (NPC) patients and carry out a comparative analysis combining with clinical case.

MATERIAL AND METHODS

Thirty NPC patients treated in our institution from September 2021 to October 2022 were prospectively enrolled. An individualized 3D printed oral stent was designed for each patient, and one set of computed tomography (CT) slices were obtained with /without wearing the oral stent, respectively. After delineation of target volumes and organs at risk (OARs) on the two CT slices, we finished two treatment plans by using the same target objectives, critical constraints and plan setup for each patient. Finally, the dose distribution and other dosimetric parameters of target volumes and OARs between the two plans were compared.

RESULTS

Tongue volume and tongue length outside of mouth was 10.4 ± 2.5 cm3 and 2.8 ± 0.6 cm, respectively, distance between dorsal surface of oral tongue and plate increased from 0.3 ± 0.3 cm to 2.2 ± 0.5 cm by wearing the oral stent. For the target volume, there was no significant difference. However, Dmax of tongue, tongue tip and periglottis decreased significantly from 6352.6 ± 259.9 cGy to 5994.9 ± 478.9 cGy, 3499.8 ± 250.6 cGy to 3357.7 ± 158.0 cGy and 6345.5 ± 171.0 cGy to 6133.4 ± 263.3 cGy, respectively (p = 0.000); Dmean of tongue, tongue tip and periglottis decreased significantly from 3714.7 ± 204.2 cGy to 3169.7 ± 200.9 cGy, 3060.8 ± 216.2 cGy to 2509.6 ± 196.7 cGy and 3853.3 ± 224.9 cGy to 3079.3 ± 222.0 cGy, respectively (p = 0.000).

CONCLUSION

The individualized 3D printed oral stent can reduce the dose of oral tissues and organs, so as to reduce the oral adverse reactions and improve the compliance of patients and the quality of their life. The technique can be used in radiotherapy of NPC patients.

Assessment of mouth opening before and after head and neck radiotherapy in patients with intraoral stents

Background

We evaluated the evolution of mouth opening before and after radiotherapy of the head and neck in patients using intraoral stents.

Materials and methods

Twenty-one patients with head and neck cancer who were indicated for radiotherapy participated in this study. Maximum interincisal opening measurements were performed before and after radiotherapy. Paired analyses of the pre- and post-radiotherapy groups were performed using paired samples t-tests and correlation analyses using Spearman's correlation test, with p < 0.05 considered statistically significant.

Results

Paired analyses of the pre- and post-radiotherapy groups revealed a statistically significant reduction in post-radiotherapy maximum interincisal opening (p < 0.001). However, only four individuals were diagnosed with trismus after radiotherapy. Regarding the correlation tests, no statistically significant differences were observed between the differences in pre- and post-radiotherapy maximum interincisal opening values and the study variables.

Conclusion

The use of prosthetic devices during head and neck radiotherapy can reduce radiation doses in areas of no interest, thereby preventing the acute and late toxicities associated with cancer therapy.

Radiation attenuation properties of materials used to fabricate radiotherapy prostheses in vitro study

PURPOSE

This study investigates the attenuation of radiation doses by four materials, heat-polymerized, and self-polymerized polymethyl methacrylate (PMMA), putty-type, and injection-type polyvinyl siloxane (PVS) impression material. This in vitro study should aid in the selection of dental materials for radiotherapy prostheses, thereby minimizing the possibility of radiotherapy side effects.

METHODS

Specimens of each type were fabricated as a 5 × 5 cm squares with a thickness of 10 mm. Heat-polymerizing PMMA, self-polymerizing PMMA, putty-type PVS impression material, and injection-type PVS impression material were selected. A calibration curve was created to determine the association of radiation doses and grayscale value. A linear accelerator was used to irradiate the specimens. The radiation doses above and below the materials were measured using radiochromic film dosimetry. After film irradiation, the pixel scale of color change was used to determine the radiation dose based on the created calibration curve. The results were exported to find average doses to calculate the percentage of the attenuated dose for a comparison of the four materials.

RESULTS

The average attenuated doses of heat-polymerizing PMMA, self-polymerizing PMMA, putty-type PVS, and injection-type PVS were 10.8%, 6.2%, 17.2%, and 14.2% respectively.

CONCLUSION

PVS showed higher attenuating radiation exposure compared with PMMA.

Over 300 Radiation Caries Papers: Reflections From the Rearview Mirror

Radiation caries (RC) is an aggressive oral toxicity in head and neck cancer survivors, which develops 6 to 12 months after head and neck radiotherapy. It initially affects the tooth cervical/incisal surfaces, and if not promptly diagnosed/managed, progresses to dental crown amputation and risk of osteoradionecrosis. It results from a multidimensional cluster of treatment-induced oral symptoms, including hyposalivation, dietary changes, and oral hygiene impairment. Although recognized as a frequent complication of radiotherapy and extensively assessed by a myriad of retrospective, in vitro, and in situ studies, RC patients are still orphans of clinically validated methods for risk prediction, prevention, and treatment of early lesions. This review provides a historical overview of science-based concepts regarding RC pathogenesis and treatment, emphasizing the growing demand for interventional clinical studies (randomized trials).

State of Rehabilitation Research in the Head and Neck Cancer Population: Functional Impact vs. Impairment-Focused Outcomes

PURPOSE OF REVIEW

Management of head and neck cancer (HNC) typically involves a morbid combination of surgery, radiation, and systemic therapy. As the number of HNC survivors grows, there is growing interest in rehabilitation strategies to manage HNC-related comorbidity. In this review, we summarize the current state of HNC rehabilitation research.

RECENT FINDINGS

We have organized our review using the World Health Organization's International Classification of Function (ICF) model of impairment, activity, and participation. Specifically, we describe the current research on rehabilitation strategies to prevent and treat impairments including dysphagia, xerostomia, dysgeusia, dysosmia, odynophagia, trismus, first bite syndrome, dysarthria, dysphonia, lymphedema, shoulder syndrome, cervicalgia, cervical dystonia and dropped head syndrome, deconditioning, and fatigue. We also discuss the broader impact of HNC-related impairment by exploring the state of rehabilitation literature on activity, participation, psychosocial distress, and suicidality in HNC survivors. We demonstrate that research in HNC rehabilitation continues to focus primarily on impairment-driven interventions. There remains a dearth of HNC rehabilitation studies directly examining the impact of rehabilitation interventions on outcomes related to activity and participation. More high-quality interventional studies and reviews are needed to guide prevention and treatment of functional loss in HNC survivors.