Stereotactic body radiotherapy: a promising treatment option for the boost of oropharyngeal cancers not suitable for brachytherapy: a single-institutional experience

Phase I feasibility study of Olaparib in combination with loco-regional radiotherapy in head and neck squamous cell carcinoma

Purpose

PARP-inhibitors have potent radiosensitizing properties in pre-clinical models. To identify the maximum tolerated dose (MTD) of the PARP-inhibitor Olaparib in combination with radiotherapy in patients with head and neck cancer, a single institutional phase-I dose escalation trial was initiated.

Patients and methods

The starting dose of Olaparib was 25 mg BID, combined with radiotherapy (70 Gy in 35 fractions). The MTD was defined as the highest dose-level at which not more than 20 % of patients experience dose-limiting toxicities (DLT) or as the highest reached dose in the absence of DLT's.

Results

One week Olaparib-only treatment (25 mg QD) was administered to all patients prior to the start of radiotherapy. In dose-level I, Olaparib (25 mg BID) was combined with accelerated radiotherapy (70 Gy in 6 weeks). Because of DLT's in 3 of the 4 treated patients (acute tracheotomy 5 and 7 months and osteoradionecrosis 7 months after treatment), the Olaparib dose was de-escalated to 25 mg QD, and combined with conventional radiotherapy (70 Gy in 7 weeks) (dose-level II). There were no DLT's observed in 5 patients treated within dose-level II. After a median follow-up of 60 months, the 4-year LRC and OS rates were 77.8 % and 88.9 %, respectively.

Conclusion

Olaparib 25 mg QD combined with conventionally fractionated radiotherapy was well tolerated and identified as the MTD while severe DLT's were observed when Olaparib 25 mg BID was combined with accelerated radiation. This combination might be further explored in future Olaparib dose escalation studies in patients with locally-advanced HNSCC unfit for cisplatin-based chemoradiotherapy.

The Evolving Role of Stereotactic Body Radiation Therapy for Head and Neck Cancer: Where Do We Stand?

Stereotactic body radiation therapy (SBRT) is a precise and conformal radiation therapy (RT) that aims to deliver a high dose of radiation to the tumor whilst sparing surrounding normal tissue, making it an attractive option for head and neck cancer (HNC) patients who are not suitable for the traditional long course of RT with comprehensive RT target volume. Definitive SBRT for HNC has been investigated in different settings, including early stage glottis cancer, and as an alternative to brachytherapy boost after external beam RT. It is also used as a primary treatment option for elderly or medically unfit patients. More recently, an SBRT combination with immunotherapy in the neoadjuvant setting for HNC showed promising results. Salvage or adjuvant SBRT for HNC can be used in appropriately selected cases. Future studies are warranted to determine the optimum dose and fractionation schedules in any of these indications.

Post radiation mucosal ulcer risk after a hypofractionated stereotactic boost and conventional fractionated radiotherapy for oropharyngeal carcinoma

BACKGROUND/PURPOSE

Post radiation mucosal ulcers (PRMU) after treatment for oropharyngeal squamous cell carcinoma (OPSCC) can have a huge negative impact on patients' quality of life, but little is known concerning risk factors and the impact of fraction size. Therefore, the goal of this study was to determine the pattern of PRMU development and to identify risk factors after a hypofractionated stereotactic body radiotherapy boost (SBRT) compared to conventionally fractionated radiotherapy for OPSCC.

MATERIAL AND METHODS

We performed a retrospective cohort study (N = 332) of OPSCC patients with ≥ 1-year disease-free survival, treated with 46 Gy Intensity Modulated Radiotherapy (IMRT) (2 Gy fractions) followed by either an SBRT boost of 16.5 Gy (5.5 Gy fractions) (N = 180), or 24 Gy IMRT (2 Gy fractions) (N = 152). PRMU (grade ≥ 2) was scored when observed > three months after the last radiotherapy (RT) fraction (CTCAE v5.0). Potential risk factors were analyzed with Cox regression models using death as competing risk. Dose at the PRMU site was calculated by projecting delineated PRMU on the planning CT.

RESULTS

All cases of PRMU (N = 64) occurred within 24 months; all were grade 2. The cumulative incidence at 2 years in the SBRT boost group was 26% (N = 46) vs. 12% (N = 18) for conventional fractionation (p = 0.003). Most PRMU developed within nine months (N = 48). PRMU occurring > nine months (N = 16) were mainly observed in the SBRT boost group (N = 15). Sex (p = 0.048), acute tube feeding (p = < 0.001), tumor subsite tonsil (p = 0.001), and N stage (p = 0.017) were associated with PRMU risk at multivariable regression in the hypofractionated SBRT boost group. All 25 delineated PRMU were located within the high dose regions.

CONCLUSION

The risk of PRMU should be included in the cost benefit analysis when considering future research using a hypofractionated SBRT boost for OPSCC patients.

The dosimetric and clinical advantages of the GTV-CTV-PTV margins reduction by 6 mm in head and neck squamous cell carcinoma: Significant acute and late toxicity reduction

PURPOSE

We aim to identify the dosimetric and clinical impact of reducing the total GTV-CTV-PTV margins in head-and-neck squamous cell carcinoma (HNSCC) treated with definitive (chemo)radiation.

MATERIALS AND METHODS

The acute and late toxicity and outcomes of 155 consecutive patients treated between February 2017 and March 2019 with GTV-CTV-PTV margins of 9 mm were compared to those of 155 consecutive patients treated with total margin of 15 mm margin, before April 2015. All patients were treated with VMAT with daily-image guidance using CBCT.

RESULTS

Reducing the GTV-CTV-PTV by 6 mm resulted in significant reduction of total irradiated volume (PTV-total) by a median of 28.1% and significant reduction of doses to all salivary glands (largest reduction ipsilateral parotid gland; median -9.6 Gy) and constrictor muscle (-6.1 Gy) with subsequent reduction of the incidence of overall acute grade 3 toxicity (47.7% for 9 mm and 66.5% for 15 mm groups, p = 0.001), grade 3 mucositis (18.1% vs. 35.5%, p < 0.001) and feeding tube-dependency at the end of treatment (24.5% vs. 40%, p = 0.005). The incidence of late grade ≥ 2 xerostomia and dysphagia were also significantly lower in the 9 mm group (31.7% vs. 58.6% p < 0.001, and 15.4% vs. 26.7%, p = 0.04). The 2-year rates of loco-regional control, disease-free and overall survival were 78.8% vs.75.8%, 70.9% vs. 64.4%, and 83.8% vs. 67.6%, (p > 0.05, all).

CONCLUSION

Reduction of the total GTV-CTV-PTV margins from 15 to 9 mm in HNSCC significantly reduced the irradiated volumes and the dose to salivary glands and constrictor muscle with significant reduction of radiation-related toxicity. The loco-regional control rates of both groups were comparable.

Stereotactic body radiotherapy (SBRT) for primary non-metastatic head and neck cancer: When less is enough

The advantage of highly conformal dose distribution and steep dose gradient has resulted in rapidly increasing use of stereotactic body radiotherapy (SBRT) in multiple cancer sites. Also there has been a surge in the use of SBRT in head neck cancer over the last decade. It is predominantly exploited in retreatment setting for recurrent and second primary head neck cancer as well as in metastatic setting. The literature on SBRT in primary non-metastatic head neck cancer is sparse and evolving. In the current review, available literature was critically analyzed focusing on the potential applications of SBRT in primary untreated non-metastatic head neck cancer. SBRT boost following external beam radiotherapy is temping as a method of dose escalation. Special attention was paid to the application of SBRT as a sole modality of treatment. The shorter treatment schedule makes it an attractive option for treatment in primary head neck cancer especially in elderly, co-morbid and medically unfits patients. Future investigation is needed to establish SBRT as an additional armamentarium in the radiotherapeutic management of head and neck cancers.

Initial Data Pooling for Radiation Dose-Volume Tolerance for Carotid Artery Blowout and Other Bleeding Events in Hypofractionated Head and Neck Retreatments

PURPOSE

Dose-volume data for injury to carotid artery and other major vessels in stereotactic body radiation therapy (SBRT)/SABR head and neck reirradiation were reviewed, modeled, and summarized.

METHODS AND MATERIALS

A PubMed search of the English-language literature (stereotactic and carotid and radiation) in April 2018 found 238 major vessel maximum point doses in 6 articles that were pooled for logistic modeling. Two subsequent studies with dose-volume major vessel data were modeled separately for comparison. Attempts were made to separate carotid blowout syndrome from other bleeding events (BE) in the analysis, but we acknowledge that all except 1 data set has some element of BE interspersed.

RESULTS

Prior radiation therapy (RT) dose was not uniformly reported per patient in the studies included, but a course on the order of conventionally fractionated 70 Gy was considered for the purposes of the analysis (with an approximately ≥6-month estimated interval between prior and subsequent treatment in most cases). Factors likely associated with reduced risk of BE include nonconsecutive daily treatment, lower extent of circumferential tumor involvement around the vessel, and no surgical manipulation before or after SBRT.

CONCLUSIONS

Initial data pooling for reirradiation involving the carotid artery resulted in 3 preliminary models compared in this Hypofractionated Treatment Effects in the Clinic (HyTEC) report. More recent experiences with alternating fractionation schedules and additional risk-reduction strategies are also presented. Complications data for the most critical structures such as spinal cord and carotid artery are so limited that they cannot be viewed as strong conclusions of probability of risk, but rather, as a general guideline for consideration. There is a great need for better reporting standards as noted in the High Dose per Fraction, Hypofractionated Treatment Effects in the Clinic introductory paper.

Phase I trial of dose-escalated stereotactic radiosurgery (SRS) boost for unfavorable locally advanced oropharyngeal cancer

Background and purpose

Patients with locally advanced oropharynx squamous cell carcinoma have suboptimal outcomes with standard chemoradiation. Here, we evaluated toxicity and oncologic outcomes of dose escalation using radiosurgical boost for patients with unfavorable oropharynx squamous cell carcinoma.

Materials and methods

Between 2010–2017, Thirty four patients with intermediate- or high-risk oropharynx squamous cell carcinoma were enrolled onto this prospective phase I trial. Each patient received concurrent cisplatin and fractionated radiotherapy totaling 60 Gy or 66 Gy followed by radiosurgery boost to areas of residual gross tumor: single fraction of 8 Gy or 10 Gy, or two fractions of 5 Gy each. Primary endpoint was treatment toxicity. Secondary endpoints were local, regional, and distant disease control.

Results

Eleven, sixteen and seven patients received radiosurgery boost with 8 Gy in 1 fraction, 10 Gy in 1 fraction, and 10 Gy in 2 fractions respectively. Acute toxicities include 4 patients with tumor necrosis causing grade 3 dysphagia, of which 3 developed grade 4 pharyngeal hemorrhage requiring surgical intervention. At 24 months after treatment, 7%, 9%, and 15% had grade 2 dysgeusia, xerostomia, and dysphagia, respectively, and two patients remained feeding tube dependent. No grade 5 toxicities occurred secondary to treatment. Local, regional, and distant control at a median follow up of 4.2 years were 85.3%, 85.3% and 88.2%, respectively. Five patients died resulting in overall survival of 85.3%.

Conclusions

This study is the first to report the use of radiosurgery boost dose escalation in patients with unfavorable oropharynx squamous cell carcinoma. Longer follow-up, larger cohorts, and further refinement of boost methodology are needed prior to implementation in routine clinical practice.

Trial Registration: Northwell Health Protocol #09-309A (NCT02703493) (https://clinicaltrials.gov/ct2/show/NCT02703493)

A multicenter prospective phase II study of postoperative hypofractionated stereotactic body radiotherapy (SBRT) in the treatment of early-stage oropharyngeal and oral cavity cancers with high risk margins: the STEREO POSTOP GORTEC 2017-03 trial

Background

Primary surgery is usually the mainstay treatment in early-stage oropharyngeal and oral cavity cancer. Typically, neck surgery is performed. Negative tumor margins are recommended (> 5 mm). If feasible, re-resection of any positive margin is preferred. Otherwise, postoperative radiotherapy is required. Adjuvant postoperative radiotherapy can be limited to the primary site for patients with pT1-T2 tumors and negative neck exploration. Currently, both fractionated external beam radiotherapy and brachytherapy can have a role in the postoperative management of early-stage oropharyngeal and oral cavity cancer with high risk margins. Another possible alternative could be postoperative stereotactic body radiotherapy (SBRT). The aim of this study is to evaluate postoperative SBRT in the treatment of early-stage oropharyngeal and oral cavity cancer with high risk margins.

Methods

The STEREO POSTOP study is a national, open-label, non-randomized phase II trial within the GORTEC network. Patients with early-stage oropharyngeal and oral cavity cancers with high risk margins indicating the need for postoperative radiation are eligible for enrollment. SBRT consists of a total dose of 36 Gy in 6 fractions over 2 weeks. The primary endpoint is severe late toxicity defined as 2-year toxicity of grade ≥ 3 according to CTCAE V4.03 classification. The secondary endpoints include acute toxicity (≤ 3 months), local and locoregional control, disease-free and overall survival, quality of life of patients, nutritional impact and predictive factors of toxicity. The experimental design chosen is a one-step Fleming plan design without interim analysis as the primary endpoint will be evaluated at a 2-year follow-up. Ninety patients will be recruited. The study was started in January 2018 with a 4-year enrollment period and an estimated completion in January 2024.

Discussion

This study is the first prospective trial to evaluate head and neck cancer postoperative SBRT in the setting of early-stage oropharyngeal and oral cavity cancers with high risk margins. SBRT is an attractive option because it delivers a highly conformal dose of radiation in a limited number of fractions (like brachytherapy but with less contraindication), with steep dose gradients resulting in reduced normal tissue irradiation and with a short overall treatment time.

Trial registration

Clinicaltrials.gov: NCT03401840, registered on 17-1-2018. Identifier in French National Agency for the Safety of Medicines and Health Products (ANSM): N°ID - RCB 2017-A02058–45, registered on July 2017.

Protocol version: Version 3 dated from 25th November 2019.

[Technical aspects and indications of extracranial stereotactic radiotherapy]

Extracranial stereotactic radiotherapy has developed considerably in recent years and is now an important part of the therapeutic alternatives to be offered to patients with cancer. It offers opportunities that have progressively led physicians to reconsider the therapeutic strategy, for example in the case of local recurrence in irradiated territory or oligometastatic disease. The literature on the subject is rich but, yet, there is no real consensus on therapeutic indications. This is largely due to the lack of prospective, randomized studies that have evaluated this technique with sufficient recoil. We propose a review of the literature on the technical aspects and indications of extracranial stereotactic radiotherapy.

[Description of the GORTEC 2017-03 study: Postoperative stereotactic radiotherapy for early stage oropharyngeal and oral cavity cancer with high risk margin (PHRC-K-16-164)]

The GORTEC 2017-03-Stereo-postop study is a phase 2, multicentric, nationwide study, funded by the hospital clinical research program (PHRC). The sponsor is Centre Jean-Perrin in Clermont-Ferrand, in partnership with the GORTEC. The principal investigators are Dr J Biau and Dr M Lapeyre. The main objective is to study severe late toxicity of postoperative stereotactic radiotherapy (6×6Gy) for early stage oropharyngeal and oral cavity cancer with high risk margins. The secondary objectives include acute toxicity, efficacy, nutritional impact and quality of life. The population is adult patients, with pT1 or pT2 squamous cell carcinoma of the oropharynx or oral cavity (except lips), without indication of neck irradiation or concomitant chemotherapy, with at risk margin (R1, less than 5mm or uncertain). Ninety patients will be included over a 2-year period; this was calculated to limit the rate of 2-year severe toxicity at 5 to 15%, with a 2-year local control of at least 80 to 90%. If this study is considered as positive, stereotactic radiotherapy (6×6Gy) could become the third therapeutic option, with brachytherapy and normofractionated intensity-modulated radiotherapy (IMRT), for postoperative irradiation of oropharyngeal and oral cavity cancer with high risk margins.

Stereotactic body radiotherapy for recurrent head and neck cancer: A critical review

The management of patients with recurrent head and neck cancers remains a challenging clinical dilemma. Concerns over toxicity with re-irradiation have limited its use in the clinical setting. Stereotactic Body Radiation Therapy (SBRT) has emerged as a highly conformal and precise type of radiotherapy and has the advantage of sparing normal tissue. Although SBRT is an attractive treatment modality, its use in the clinic is limited, given the technically challenging nature of the procedure. In this review, we attempt to provide a comprehensive overview of the role of re-irradiation in patients with recurrent head and neck cancers, with particular attention to the advent of SBRT and its use with systemic therapies such as cetuximab. In the second portion of this review, we present our systematic review of published experiences with SBRT in recurrent head and neck cancers in an attempt to provide data on response rates (RR), overall survival and toxicity. © 2016 Wiley Periodicals, Inc. Head Neck 39: 595-601, 2017.

Dietary counselling and nutritional support in oropharyngeal cancer patients treated with radiotherapy: persistent weight loss during 1-year follow-ups

BACKGROUND/OBJECTIVES

The need for dietary counselling and nutritional support in oropharyngeal cancer patients is generally accepted. However, evidence for the effectiveness is sparse. The aim of this study was to describe dietary counselling, nutritional support, body weight and toxicity during and after treatment, and investigate the effect of pre-treatment body mass index (BMI) on survival in oropharyngeal cancer patients.

SUBJECTS/METHODS

A retrospective chart review was made in 276 oropharyngeal cancer patients treated with radiotherapy (RT). End points were dietary consultations, weight loss, toxicity, overall survival and disease-free survival.

RESULTS

Almost all oropharyngeal cancer patients received dietary counselling (94%) and nutritional support (99%). Dietary counselling decreased sharply shortly after treatment to 38% at 1 year after treatment. Overall weight loss increased during the first year of follow-up and ranged from 3% at start of RT, until 11% at 1 year after RT. Overall survival was significantly longer for patients with a BMI above average (P=0.01). Acute dysphagia (P=0.001), mucositis (P=0.000) and toxicity grade 3 (P=0.002) were significantly more prevalent in patients who had lost 10% or more of their body weight.

CONCLUSIONS

This study showed that patients continue to lose body weight during and until 1 year after treatment, despite nutrition support and frequent dietetic consultation. A BMI above average appears to increase survival time. Future studies, preferably randomized trials, are needed to compare standard dietary counselling with more intensive dietary counselling that consists of earlier and/or prolonged treatment.

[Intensity-modulated radiation therapy and stereotactic body radiation therapy for head and neck tumors: evidence-based medicine]

Over the last decade, there have been many technical advances in radiation therapy, such as the spread of intensity-modulated conformal radiotherapy, and the rise of stereotactic body radiation therapy. By allowing better dose-to-target conformation and thus better organs at risk-sparing, these techniques seem very promising, particularly in the field of head and neck tumors. The present work aims at analyzing the level of evidence and recommendation supporting the use of high-technology radiotherapy in head and neck neoplasms, by reviewing the available literature.

Brachytherapy or stereotactic body radiotherapy boost for early-stage oropharyngeal cancer: comparable outcomes of two different approaches

OBJECTIVES

To compare outcome, toxicity and QoL of two boost modalities for T1-2 oropharyngeal carcinoma (OPC).

MATERIALS AND METHODS

Between 2000 and 2012, 250 consecutive patients with T1-2N0-3 were treated with 46-Gy of IMRT followed by boost using brachytherapy (BTB) or stereotactic body radiotherapy (CKB). Endpoints were local control (LC), disease-free survival (DFS), overall survival (OS), toxicity and prospective QoL-assessment.

RESULTS

The 3-year actuarial incidence of LC were 97% and 94% for the CKB and BTB, respectively (p=0.33). The figures for DFS were 92% and 86% (p=0.15) and for OS were 81% and 83% (p=0.82), respectively. The incidence of tube feeding were 17% and 20%, respectively (p=0.47). The figures for grade ⩾2 late dysphagia were 11% and 8% (p=0.34) and for xerostomia were 16% and 12% (p=0.28), respectively. For both modalities, clinically relevant deteriorations were seen on all scales at end of treatment but the scores returned to almost baseline levels within 6-12months, with exception of QLQ-H&N35-xerostomia. The difference on that scale was neither statistically significant nor clinically relevant between both modalities.

CONCLUSION

Comparable outcome, toxicity and QoL-scores were achieved with both modalities. In the light of the logistical hassle around the implantation, the need of dexterity, and the risk of anaesthesia and peri-operative complications associated with BTB, CKB might be regarded as the optimal option to boost early-stage OPC. However, in radiotherapy departments where no facilities are available for stereotactic radiotherapy, BTB is an elegant option to achieve excellent outcome with low toxicity profile and good QoL.

The impact of treatment modality and radiation technique on outcomes and toxicity of patients with locally advanced oropharyngeal cancer

OBJECTIVES/HYPOTHESIS

To investigate the impact of treatment modality and radiation technique on oncologic outcomes and toxicity of patients with locally advanced oropharyngeal cancer (OPC).

STUDY DESIGN

Retrospective analysis of outcomes and toxicity.

METHODS

Between 2000 and 2011, 204 consecutive patients with locally advanced OPC were treated with definitive (chemo)radiotherapy using 3-dimensional conformal (3DCRT) or intensity-modulated radiotherapy (IMRT). Endpoints were local control (LC), regional control (RC), disease-free survival (DFS), cause-specific survival (CSS), and overall survival (OS), and toxicity.

RESULTS

After a median follow-up of 44 months (range 4-134), the 5-year Kaplan-Meier estimates of LC, RC, DFS, CSS, and OS were 78%, 92%, 60%, 64%, and 48%, respectively. Grade 3 mucositis and dysphagia (feeding-tube dependency) were reported in 75% and 65%, respectively. The overall incidence of grade ≥ 2 and grade 3 late toxicities were 44% and 16%, respectively. Dysphagia and xerostomia were the most frequently reported late toxicity. Chemotherapy was significantly predictive for improved outcomes and increased toxicity. IMRT was significantly correlated with reduced toxicity.

CONCLUSIONS

Compared to radiation alone, chemoradiotherapy significantly improved oncologic outcomes, but with significantly increased toxicity. Compared to 3DCRT, the introduction of IMRT resulted in a significant reduction of acute and late toxicity with slightly better, or at least comparable, outcomes. Despite the improvements achieved by the implementation of chemo-IMRT, different new strategies to further improve outcome and reduce toxicity need to be thoroughly investigated in prospective, preferably, randomized trials.

Unilateral neck irradiation for well-lateralized oropharyngeal cancer

BACKGROUND AND PURPOSE

To investigate the impact of unilateral neck irradiation (UNI) of well-lateralized oropharyngeal cancer (OPC) on outcome and toxicity.

MATERIALS AND METHODS

Unilateral neck IMRT was applied to 185 consecutive patients with well-lateralized OPC (restricted to tonsillar fossa, soft palate with at least 1cm from midline or lateral pharyngeal wall). Endpoints were regional control (RC), local control (LC), disease-free survival (DFS), overall survival (OS), and toxicity.

RESULTS

Six regional failures were reported (3.2%); 2 were contralateral (1.1%). The 5-year Kaplan-Meier estimates of RC, LC, DFS, and OS were 96%, 91%, 84%, and 70%, respectively. Feeding tube was given to 11.3%. Chemotherapy was significantly predictive for toxicity. However, no patient was still feeding tube dependent 6 weeks after treatment. Overall grade 3 late toxicity was 2.2%. Grade 3 xerostomia was reported in only 1 patient while no patient developed grade 3 dysphagia.

CONCLUSION

This largest study on unilateral neck IMRT for well-lateralized OPC showed excellent outcome and favorable toxicity profile. Given the increasing incidence of OPC, especially among younger patients, and the favorable results reported in the current study and by other investigators, expanding the indications for UNI still needs to be further investigated in prospective, preferably, randomized trials.

Clinical outcomes of single or oligo-fractionated stereotactic radiotherapy for head and neck tumors using micromultileaf collimator-based dynamic conformal arcs

PURPOSE

To assess the clinical outcomes of single or oligo-fractionated stereotactic radiotherapy (SRT) using dynamic conformal arcs (DCA) for head and neck tumors (HNTs).

METHODS

Thirty-four consecutive patients with 35 lesions treated between 2005 and 2009 were retrospectively evaluated, of whom 85.7 % had recurrent or metastatic disease, and 45.7 and 34.3 % had previous radiotherapy and surgery, respectively. The median SRT dose was 22.3 Gy (11.2-32.8) in 2-4 fractions with a median interval of 7 days and 10.4 Gy (9.2-12.4) in one fraction. SRT was combined with upfront conventionally fractionated RT in 48.6 % of patients.

RESULTS

The median follow-up periods were 18.4 months (2-84.1) for the entire cohort and 49.6 months for the survivors. The 1- and 2-year local control (LC) rates were 84.3 and 70.5 %, with the 1- and 2-year overall survival (OS) rates of 78.6 and 51.6 %. LC was significantly better for tumor volumes <25.6 cm(3) (p = 0.001). OS was significantly longer in patients without any disease outside the SRT site (p < 0.001), whereas LC after the SRT did not affect the OS. Late adverse events occurred in 9 patients, including cranial nerve (CN) injury (grade 3/4) in 2, brain radionecrosis in 5 (grade 1), and fatal bleeding in 2 patients harboring uncontrolled lesions abutting the carotid artery.

CONCLUSIONS

DCA-based SRT can confer relatively long-term LC with acceptable toxicity in selected patients with HNTs. The patients with CN involvement or tumor volume ≥25.6 cm(3) were deemed unsuitable for this treatment regimen.