High-dose-rate brachytherapy using molds for lip and oral cavity tumors

Is There Still a Place for Brachytherapy in the Modern Treatment of Early-Stage Oral Cancer?

Simple Summary

Brachytherapy involves the direct application of radioactive sources to the tumour. This technique is characterised by a delivery of high dose of radiation to the target volume and simultaneous sparring of healthy tissues. Historically, low-dose-rate brachytherapy played an important role in the treatment of early-stage oral cancer, with treatment outcomes that were comparable to surgery. Interest in brachytherapy as a primary treatment for oral cancer has declined in recent years due to the emergence of better surgical techniques, to advances in external beam radiotherapy, and to concerns regarding toxicity of modern high-dose-rate brachytherapy. At present, the main indications for brachytherapy are in the postoperative setting due to the superior dose conformity and better quality of life offered by brachytherapy compared to external beam radiation therapy. Postoperative brachytherapy can be administered as a monotherapy in early-stage tumours (T1N0) and in combination with elective neck dissection or EBRT to treat larger or deeper tumours. Brachytherapy yields excellent results for lip carcinoma in older patients and in tumours with unfavourable localisations. Brachytherapy is an effective salvage therapy for local recurrences in previously-irradiated areas.

Abstract

Brachytherapy (BT) involves the direct application of radioactive sources to the tumour. This technique is characterised by a steep dose gradient, the delivery of high-dose radiation to the target volume centre, and the sparing of surrounding healthy tissues. Low-dose-rate (LDR) BT and manual afterloading played an important role in the treatment of early-stage oral cancer, with treatment outcomes that were comparable to surgery. Interest in BT as a primary treatment for oral cancer has declined in recent years due to the emergence of better surgical techniques, the switch from LDR BT to high-dose-rate (HDR) BT (which has a higher risk of complications), and to advances in external beam radiotherapy (EBRT). At present, the main indications for BT are in the postoperative setting due to the superior dose conformity and better quality of life offered by BT versus EBRT. Postoperative BT can be administered as monotherapy in early-stage (T1N0) cancers and in combination with elective neck dissection or EBRT to treat larger or deeper tumours. BT yields excellent results for lip carcinoma in older patients and in tumours with unfavourable localisations. BT is an effective salvage therapy for local recurrences in previously-irradiated areas. Despite its many advantages, brachytherapy is a complex treatment requiring meticulous technique and close cooperation between the radiation oncologist, physicist, and surgeon.

Surface mould brachytherapy in oral and oropharyngeal cancers

INTRODUCTION

There are insufficient data on surface mold brachytherapy (SMB) in treating oral cancers. We reviewed our institutional experience to investigate the efficacy and toxicity of this treatment modality.

MATERIAL AND METHODS

We retrospectively reviewed all the patients treated between 1989 and 2018 with high-dose-rate iridium-192 SMB for oral and oropharyngeal squamous cell carcinomas at our institution. Surface mold brachytherapy was delivered via an acrylic surface mold with 1-5 inserted catheters spaced 1 cm apart fabricated by our dental oncologist. The Kaplan-Meier product estimator was used to assess local control (LC), locoregional control (LRC), distant metastasis-free survival (DMFS), and overall survival (OS). Cox proportional hazards regression analysis was used to assess the relationship of various variables and patient outcomes.

RESULTS

Eighteen patients met the inclusion criteria and were evaluated. Indications for treatment were primary tumor (n = 13), local recurrence (2), locoregional recurrence (1), and oligometastatic disease (1). Ten patients received SMB alone and 8 received external beam radiotherapy with an SMB boost. The acute toxicity outcomes were as follows: no toxicity (n = 1), grade 1 (7), grade 2 (9), and grade 3 (1). Late effects were rare, only occurring in 3 patients. The one- and two-year LC were 81% and 68%, LRC 77% and 64%, DMFS 81% and 81%, and OS 77% and 46%.

CONCLUSIONS

Surface mold brachytherapy is a viable modality as either primary or boost treatment for superficial oral cancers. In our patients, this treatment method has a low toxicity profile and resulted in reasonable LC.

High-Dose-Rate Brachytherapy for Primary Treatment of Refractory Proliferative Verrucous Leukoplakia of the Hard Palate

Oral proliferative verrucous leukoplakia (PVL) is a rare, progressive form of leukoplakia with a high rate of malignant transformation. No therapies are known to lower the rate of malignant transformation and prevent a recurrence.

An 84-year-old patient with a years-long history of symptomatic PVL of the hard palate refractory to CO2 laser ablation presented to the radiation oncology clinic for consideration of non-surgical management. High dose rate brachytherapy was used to deliver 36 Gy in 12 fractions to the hard palate using an Ir-192 source with a custom-molded applicator.

By three months of follow-up, the patient had complete regression of the PVL and resolution of acute mucositis. With 18 months of follow-up, the patient remains disease- and symptom-free without toxicities of treatment.

High dose rate surface applicator brachytherapy is a feasible and potentially effective treatment for oral PVL, yielding durable control with low long-term toxicity.

High dose rate interstitial brachytherapy for early stage lip cancer using customized dental spacer

The present study aimed to report the efficacy and toxicity of our high-dose-rate (HDR) brachytherapy for early stage lip cancer (LC) using customized dental spacers. A retrospective analysis was performed among six patients with early stage LC treated with HDR interstitial brachytherapy between April 2015 and August 2019 using customized dental spacers. The total treatment dose was 49 Gy/7 fractions or 54 Gy/9 fractions. The median follow-up duration for the patients was 13 (range: 2-52) months. All patients completed the entire brachytherapy protocol safely and have experienced no local recurrence thus far. The CTV D100 and D90 values per fraction were median 100 (range: 98.3-100) % prescribed dose (PD) and median 133.4 (range: 129.3-138.9) % PD, respectively. The D2cc and D0.1cc values per fraction for the mandible were median 1.07 (range, 0.79-1.88) Gy and median 1.65 (range: 1.21-2.83) Gy, D2cc and D0.1cc values per fraction for oral cavity were median 1.48 (range, 1.31-1.72) Gy and median 2.73 (range: 1.79-2.88) Gy, respectively. Acute toxicities encountered were mucositis and lip edema limited to the irradiated area; none of them was beyond grade 2 and all were resolved within 1-2 months after treatment. We did not observe any late grade 2 adverse events or worse. This study shows that the adverse effects of HDR brachytherapy for early stage LC can be minimized using a dental spacer. Cooperation with the dentistry department is essential to make spacers that are individually customized for each patient.

Squamous Cell and Adenoid Cystic Carcinoma Collision Tumor of the Soft Palate Treated with Surface Mold Brachytherapy

Simultaneous primary cancers are rare in the oropharynx. This report describes the first reported case of a collision tumor of squamous cell and adenoid cystic carcinoma in the soft palate. The patient was immunosuppressed with a history of liver transplantation, smoking and heavy alcohol drinking. He was treated with wide local excision followed by adjuvant radiotherapy with surface acrylic mold brachytherapy. This technique was used instead of external beam radiotherapy in order to minimize toxicity. The patient tolerated the treatment well and with the only acute grade two mucositis at the soft palate and minimal late toxicity. There is no evidence of disease recurrence and the patient continues to maintain excellent quality of speech and swallowing 14 months after treatment completion.

Individual 3-dimensional printed mold for treating hard palate carcinoma with brachytherapy: A clinical report

This clinical report describes the use of a 3-dimensional (3D) printer to create an individual mold for delivering high-dose-rate interventional radiotherapy for hard palate cancer. The maxillary teeth and palate were scanned with an intraoral scanner (3Shape TRIOS 3). The scan was transformed into a mesh using the standard tessellation language (STL) format and aligned with Digital Imaging and Communications in Medicine (DICOM) computed tomography (CT) images using free Blue Sky Plan 4 planning software. A mold was generated by tracing a guideline around the gingival margins of the maxillary teeth and palate on the scan mesh in accordance with established parameters. All data were imported into computer-aided design (CAD) software. For this patient, 3 parallel 2.2-mm-diameter ducts were placed 10 mm from each other in the mold mesh. A CT scan of the patient's mouth with the mold in place was used for treatment planning. Treatment was delivered by means of microSelectron digital afterloading.

[Brachytherapy for head and neck cancers]

The main indications of the brachytherapy of head and neck cancers are the limited tumours of the lip, the nose, the oral cavity and the oropharynx. Nasopharynx tumours are nowadays treated by intensity-modulated radiotherapy. This technique can be exclusive, associated with external radiotherapy or postoperative. It can also be a salvage treatment for the second primaries in previously irradiated areas. If the low dose rate brachytherapy rules remain the reference, the pulse dose rate technique allows the prescription of the dose rate and the optimisation of the dose distribution. Results of high dose rate brachytherapy are now published. This paper reports the recommendations of the Gec-ESTRO, published in 2017, and takes into account the data of the historical low dose rate series, and is upgraded with the pulsed-dose rate and high dose rate series.

Clinical outcomes with high-dose-rate surface mould brachytherapy for intra-oral and skin malignancies involving head and neck region

PURPOSE

The literature and experience of high-dose-rate (HDR) surface mould brachytherapy (SMB) in head and neck cancer is sparse. We report our institutional experience of SMB for such tumours.

MATERIAL AND METHODS

Thirty-five patients with malignant localized early T1/T2, N0 (21 intra-oral and 14 skin) tumours treated with SMB during 2008-2014 were analyzed. Treatment was delivered using HDR ¹⁹²Ir source to a median dose of 49 Gy (range, 38.5-52.5 Gy) as radical brachytherapy and 18 Gy (range, 15.5-30 Gy) as boost with 3-4 Gy/fraction twice daily using customized surface mould.

RESULTS

Median follow-up was 52 months (range, 6 to 98 months). Local control (LC) for skin tumours and intra-oral malignancies at 5 years were 92% and 76%, respectively. Five-year cause specific survival was 92%. For T1 and T2 tumours, 5 year LC was 94.2% and 68.2%, respectively. T stage (p < 0.04) and dose/fractions (p < 0.003) were the only significant prognostic factors for LC on univariate analysis.

CONCLUSIONS

Surface mould brachytherapy results in excellent LC rates for skin tumours and T1 intraoral tumours when considered as radical treatment, and preferable to consider it as a boost for T2 intraoral tumours. Surface mould brachytherapy results in excellent organ and function preservation.

GEC-ESTRO ACROP recommendations for head & neck brachytherapy in squamous cell carcinomas: 1st update - Improvement by cross sectional imaging based treatment planning and stepping source technology

The Head and Neck Working Group of the GEC-ESTRO (Groupe Européen de Curiethérapie - European Society for Therapeutic Radiology and Oncology) published in 2009 the consensus recommendations for low-dose rate, pulsed-dose rate and high-dose rate brachytherapy in head & neck cancers. The use of brachytherapy in combination with external beam radiotherapy and/or surgery was also covered as well as the use of brachytherapy in previously irradiated patients. Given the developments in the field, these recommendations needed to be updated to reflect up-to-date knowledge. The present update does not repeat basic knowledge which was published in the first recommendation but covers in a general part developments in (1) dose and fractionation, (2) aspects of treatment selection for brachytherapy alone versus combined BT+EBRT and (3) quality assurance issues. Detailed expert committee opinion intends to help the clinical practice in lip-, oral cavity-, oropharynx-, nasopharynx-, and superficial cancers. Different aspects of adjuvant treatment techniques and their results are discussed, as well the possibilities of salvage brachytherapy applications.

The "decay" of brachytherapy use in tumors of the oral cavity: A population-based patterns of care and outcomes analysis from 1973 to 2012

PURPOSE

We aimed to evaluate if use of brachytherapy (BT) is associated with improved survival in patients with oral cavity cancer who do not receive surgery and to analyze patterns of care.

METHODS AND MATERIALS

We queried the Surveillance, Epidemiology, and End Results database for patients who received radiation therapy for squamous cell carcinoma of the oral cavity between 1973 and 2012. Patients were grouped by treatment modality: external beam radiotherapy alone vs. external beam radiotherapy + BT. Surgical patients were excluded. Trends in BT utilization over the study period and patterns of care were analyzed. Propensity scores were generated, and a nearest-neighbor matching algorithm was used to balance the 2 groups. Cox regression modeling was used to estimate the effect of BT on overall survival. Sensitivity analysis was conducted to estimate the effect of unmeasured confounders on the analysis.

RESULTS

Of 5,161 patients with squamous cell carcinoma of the oral cavity who received radiotherapy, 12% of patients received BT. The rate of BT use has decreased by 0.58% per year (p < 0.001). Factors that predicted for omission of radiation therapy included age ≥ 65 years (adjusted odds ratio [aOR], 0.56; p < 0.001), regional nodal disease (aOR, 0.57; p < 0.001), and black race (aOR, 0.45; p < 0.001). Use of BT was associated with a decreased risk of death (hazard ratio, 0.75; p < 0.001).

CONCLUSIONS

The use of BT is associated with improved survival in oral cavity tumors treated with definitive radiotherapy. Rates of BT utilization have declined by 0.58% per year and are currently very low.