Construction and clinical evaluation of a new customized bite block used in radiotherapy of head and neck cancer

Effectiveness of intraoral stents in reducing oral adverse events during radiotherapy for maxillary or nasal cavity malignant tumors

PURPOSE

Many patients experience oral adverse events during head and neck cancer radiotherapy (RT). The methods of management of such events are under debate. One such technique is the intraoral stent (IOS) technique, which removes normal tissue from the irradiation field. This retrospective study examined the factors associated with the occurrence of oral mucositis (OM) and dysgeusia and the efficacy of IOSs in preventing them.

METHODS

Twenty-nine patients who underwent RT in the maxilla or nasal cavity between 2016 and 2022 were included. They were investigated for background characteristics, treatment factors (IOS and dose-volume histogram), and oral adverse events (OM and dysgeusia).

RESULTS

Significant risk factors for the incidence of grade ≥ 2 (Common Terminology Criteria for Adverse Events v5.0) OM were the non-use of IOSs (p = 0.004) and diabetes (p = 0.025). A significant risk factor for the incidence of grade ≥ 1 dysgeusia was concomitant chemotherapy (p = 0.019). The radiation dose to the tongue was significantly lower in the IOS group than in the non-IOS group.

CONCLUSION

Our findings suggest that the use of an IOS during RT reduces the severity of OM by reducing irradiation to the tongue. Therefore, the use of an IOS is recommended during RT performed in the maxilla or nasal cavity.

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.

Oral Sequelae after Head and Neck Radiotherapy: RCT Comparing 3D-Printed Tissue Retraction Devices with Conventional Dental Splints

OBJECTIVES

To evaluate oral sequelae after head and neck radiotherapy (RT) when using two different types of intraoral appliances. Thermoplastic dental splints (active control) protect against backscattered radiation from dental structures. Semi-individualized, 3D-printed tissue retraction devices (TRDs, study group) additionally spare healthy tissue from irradiation.

MATERIALS AND METHODS

A total of 29 patients with head and neck cancer were enrolled in a randomized controlled pilot trial and allocated to receive TRDs (n = 15) or conventional splints (n = 14). Saliva quality and quantity (Saliva-Check, GC), taste perception (Taste strips, Burghart-Messtechnik), and oral disability (JFLS-8, OHIP-14, maximum mouth opening) were recorded before and 3 months after RT start. Radiotherapy target volume, modality, total dose, fractionation, and imaging guidance were case-dependent. To evaluate intra-group developments between baseline and follow-up, nonparametric Wilcoxon tests were performed. Mann-Whitney-U tests were applied for inter-group comparisons.

RESULTS

At follow-up, taste perception was unimpaired (median difference in the total score; TRDs: 0, control: 0). No significant changes were found regarding oral disability. Saliva quantity (stimulated flow) was significantly reduced with conventional splints (median -4 mL, p = 0.016), while it decreased insignificantly with TRDs (median -2 mL, p = 0.07). Follow-up was attended by 9/15 study group participants (control 13/14). Inter-group comparisons showed no significant differences but a tendency towards a better outcome for disability and saliva quality in the intervention group.

CONCLUSION

Due to the small cohort size and the heterogeneity of the sample, the results must be interpreted with reservation. Further research must confirm the positive trends of TRD application. Negative side-effects of TRD application seem improbable.

Design of 3D-printed universal oral stent for tongue immobilization in head and neck radiotherapy

The primary treatment for head and neck cancer is radiotherapy, which can cause complications and effects, such as the ability to speak, taste, produce saliva, and swallow. An oral stent is an immobilization tool for minimizing the dose in the tongue (or hard palate) by locking the tongue position during radiation delivery. It can improve the treatment accuracy due to less uncertainty caused by tongue position uncertainty between treatment fractions. However, commercial oral stents are not widely adopted in developing countries due to their unaffordable price. This study aimed to design the universal oral stent (UOS) to achieve high efficiency, ease to use, and low-cost fabrication based on 3D printing technology. There were five experiments to evaluate the UOS design and fabrication versus the modified cut syringe, including finite element analysis (FEA), the usability test, the micro Vickers hardness test, single beam dose analysis, and dose calculation on treatment plan simulations. The proposed UOS design and fabrication presented a high capability to apply for clinical use.

Radiotherapy of tongue cancer using an intraoral stent: a pilot study

Aim:

The aim was to evaluate the feasibility of an intraoral stent (10 and 20 mm thickness) in radiotherapy of tongue cancer, and to measure the reduction in acute mucositis in the palate.

Materials and method:

There were six patients in the intervention group, and seven patients in the control group. Target coverage was measured by the minimum dose covering 98% of the clinical target volume (CTV). Data were collected from the planning CT and daily cone-beam computer tomography (CBCT).

Results:

The 10 and 20 mm stent yielded a mean distance of 26 and 36 mm, respectively, between the tongue and the hard palate. We found comparable dose coverage of the CTV in the treatment plan, and on the CBCT. The stent reduced mean dose to the hard palate by 61.0% (p = 0.002). Dose to the soft palate was not reduced (p = 0.18). Average Common Terminology Criteria for Adverse Events (CTCAE) mucositis scores of the hard palate were 0 and 0.8 in the intervention and control group, respectively. The mucositis scores of the soft palate were 1.2 and 1.8.

Findings:

Use of an intraoral stent substantially reduced the dose to the hard palate. CTV coverage was maintained. We did not find any significant reduction in visually scored radiation-induced mucositis.

Management and work-up procedures of patients with head and neck malignancies treated by radiation

Radiotherapy alone or in association with systemic treatment plays a major role in the treatment of head and neck tumours, either as a primary treatment or as a postoperative modality. The management of these tumours is multidisciplinary, requiring particular care at every treatment step. We present the update of the recommendations of the French Society of Radiation Oncology on the radiotherapy of head and neck tumours from the imaging work-up needed for optimal selection of treatment volume, to optimization of the dose distribution and delivery.

Intraoral radiation stents-Primer for clinical use in head and neck cancer therapy

Intraoral radiation stents (IRS) are prosthetic devices that assist in the effective delivery of radiation to tumor tissues and aim to avoid unnecessary radiation to adjacent healthy tissues, thus limiting postradiotherapy toxicities. They are used to protect or displace vital structures, assist in positioning of the treatment beam for effective administration of radiotherapy, carry a radioactive material, shield healthy tissues of the oral cavity, and/or maintain the desired mouth opening during radiotherapy. With close collaboration between radiation oncologist and oral health care provider, several IRS can be fabricated by the latter for appropriate targeting and delivery of planned radiation dose and optimized treatment results. Modification of these IRS based on individual patient need is recommended to maximize prosthesis utility. The purpose of this review is to discuss the various types of IRS and highlight their clinical utility and benefits in patients receiving radiation therapy in the head and neck cancers.

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

STATEMENT OF PROBLEM

Intraoral stents have been provided to minimize acute and chronic toxicities induced by radiotherapy, including oral mucositis, salivary changes, trismus, radiation-related caries, and osteoradionecrosis. However, a systematic review and meta-analysis is necessary to determine their effectiveness.

PURPOSE

The purpose of this systematic review and meta-analysis was to determine the effectiveness of intraoral stent use and determine whether these prosthetic devices can reduce radiation dosage to nontargeted oral tissues and adverse effects related to head and neck radiation.

MATERIAL AND METHODS

Two independent reviewers made a systematic search for articles published from January 2010 to March 2020 in 3 databases, supplemented by a manual search. Studies were included if they were clinical trials (randomized controlled trials, both prospective and retrospective), published in English, and evaluated radiation dose and oral adverse side effects (acute or chronic) induced by radiotherapy of participants with and without intraoral stents.

RESULTS

The search strategy identified 201 studies; of which, 9 were included. A total of 251 participants were evaluated; of whom, 168 (77.3%) used intraoral stents and 57 (22.7%) were treated with radiotherapy without a prosthetic device. A statistically significant difference was found regarding the use of intraoral stents for preventing oral mucositis (P<.001), salivary changes (P=.003), and trismus (P<.02). A funnel plot showed asymmetry among the differences of means in all selected studies.

CONCLUSIONS

Intraoral stents have a positive effect on preventing oral mucositis. Further clinical trials are needed to address the flaws identified in the present systematic review.

Taste dysfunction following radiotherapy to the head and neck: A systematic review

BACKGROUND

An intact sense of taste provides pleasure, supports sustenance and alerts the body to toxins. Head and neck cancer (HNC) patients who receive radiotherapy (RT) are high-risk for developing radiation-induced taste dysfunction. Advances in RT offer opportunities for taste-preserving strategies by reducing dose to the gustatory organs-at-risk.

METHODS

PubMed, Medline and EMBASE were searched for publications reporting on taste, RT and HNC. Randomised trials, cohort studies and cross-sectional studies were included.

RESULTS

31 studies were included in this review. Meta-analysed prevalence of acute taste dysfunction following RT was approximately 96% (95% CI 64 to 100%) by objective measures and 79% (95% CI 65 to 88%) by subjective measures, with the majority of patients showing at least partial recovery. Long-term dysfunction was seen in ~25% of patients. Taste dysfunction was associated with sequalae including weight loss and reduced quality-of-life (QoL). Taste dysfunction was more common when the oral cavity, and specifically the anterior two-thirds of the tongue, was irradiated, suggesting a dose constraint for taste preservation might be feasible. Proton beam therapy and customised bite blocks reduced dose to the gustatory field and subsequent loss of taste.

CONCLUSIONS

Taste dysfunction following RT is common and negatively affects patients' nutritional status and QoL. Decisions about treatment strategies, including choice of RT modality, dose distribution across the gustatory field and the use of adjuncts like bite blocks may be beneficial. However, evidence is limited. There is a pressing need for randomised studies or large prospective cohort studies with sufficient adjustment for confounders.

Benefits of intraoral stents in patients with head and neck cancer undergoing radiotherapy: Systematic review

Intraoral stents aim to reduce the oral complications associated with head and neck cancers radiotherapy. The aim of this study is to determine the benefits associated with these devices. A systematic review was conducted in PubMed, Web of Science, and Scopus databases selecting full articles published in English, Portuguese, or Spanish until June 6, 2020 (PROSPERO registration: CRD42020185065). The studies were evaluated by Hadorn and Somerfield criteria and guidelines were established. Nineteen studies were identified suggesting the use of intraoral stent for radiotherapy for patients with cancer on/near the mandible to reduce oral mucositis, trismus, xerostomia (LoE III), and dose in healthy structures (LoE IV) and for cancer on/near the maxilla to reduce oral mucositis and dose in healthy structures (LoE IV). Despite the limited scientific evidence, several benefits associated with the use of intraoral stent for radiotherapy of the head and neck neoplasia have been reported.

Radiation-Induced Salivary Gland Dysfunction: Mechanisms, Therapeutics and Future Directions

Salivary glands sustain collateral damage following radiotherapy (RT) to treat cancers of the head and neck, leading to complications, including mucositis, xerostomia and hyposalivation. Despite salivary gland-sparing techniques and modified dosing strategies, long-term hypofunction remains a significant problem. Current therapeutic interventions provide temporary symptom relief, but do not address irreversible glandular damage. In this review, we summarize the current understanding of mechanisms involved in RT-induced hyposalivation and provide a framework for future mechanistic studies. One glaring gap in published studies investigating RT-induced mechanisms of salivary gland dysfunction concerns the effect of irradiation on adjacent non-irradiated tissue via paracrine, autocrine and direct cell-cell interactions, coined the bystander effect in other models of RT-induced damage. We hypothesize that purinergic receptor signaling involving P2 nucleotide receptors may play a key role in mediating the bystander effect. We also discuss promising new therapeutic approaches to prevent salivary gland damage due to RT.

The impact of tongue-deviating and tongue-depressing oral stents on long-term radiation-associated symptoms in oropharyngeal cancer survivors

OBJECTIVES

To evaluate whether the use of oral stents during intensity modulated radiation therapy (IMRT) for oropharyngeal cancer (OPC) is associated with long-term patient reported symptoms.

MATERIALS AND METHODS

Data was obtained from a prospective observational study of disease-free head and neck cancer survivors. Radiation-associated patient reported symptoms were assessed using the MD Anderson Symptom Inventory Head and Neck module (MDASI-HN). Scores of ≥5 (11-point Likert scale, 0-10) were considered moderate/severe. Stratification was performed regarding IMRT volume (uni- versus bilateral neck) and stent utilization, with non-parametric analyses between groups.

RESULTS

462 OPC survivors formed the cohort (54% tonsil, 46% base of tongue primaries). A tongue-deviating stent was used in 17%, tongue-depressing stent in 46%, and no stent in 37%. Median prescribed dose to the high dose clinical target volume was 66.0 Gy. Median follow-up from RT to MDASI-HN assessment was 68 months. Twenty percent had received unilateral neck RT (all had tonsil primaries), in whom a significant improvement in the proportion of patients with moderate/severe taste impairment (2% vs. 15%, p = 0.047) and lack of appetite (0% vs. 9%, p = 0.019) was associated with the use of tongue-deviating stents compared to no oral stent. In those who had received bilateral neck RT, a significant improvement in the proportion of patients with moderate/severe difficulty swallowing/chewing was associated with use of a tongue-depressing stent (21% vs. 31% without oral stent, p = 0.013).

CONCLUSION

Disease-site specific select use of oral stents during IMRT was associated with reduced long-term patient reported symptoms in OPC survivors.