Toxicities Following Stereotactic Ablative Radiotherapy Treatment of Locally-Recurrent and Previously Irradiated Head and Neck Squamous Cell Carcinoma

Stereotactic Body Radiotherapy in Recurrent and Oligometastatic Head and Neck Tumours

The treatment of head and neck cancers (HNCs) encompasses a complex paradigm involving a combination of surgery, radiotherapy, and systemic treatment. Locoregional recurrence is a common cause of treatment failure, and few patients are suitable for salvage surgery. Reirradiation with conventional radiation techniques is challenging due to normal tissue tolerance limits and the risk of significant toxicities. Stereotactic body radiotherapy (SBRT) has emerged as a highly conformal modality that offers the potential for cure while limiting the dose to surrounding tissue. There is also growing research that shows that those with oligometastatic disease can benefit from curative intent local ablative therapies such as SBRT. This review will look at published evidence regarding the use of SBRT in locoregional recurrent and oligometastatic HNCs.

Metastases-directed stereotactic body radiotherapy in combination with targeted therapy or immunotherapy: systematic review and consensus recommendations by the EORTC-ESTRO OligoCare consortium

Stereotactic body radiotherapy (SBRT) for patients with metastatic cancer, especially when characterised by a low tumour burden (ie, oligometastatic disease), receiving targeted therapy or immunotherapy has become a frequently practised and guideline-supported treatment strategy. Despite the increasing use in routine clinical practice, there is little information on the safety of combining SBRT with modern targeted therapy or immunotherapy and a paucity of high-level evidence to guide clinical management. A systematic literature review was performed to identify the toxicity profiles of combined metastases-directed SBRT and targeted therapy or immunotherapy. These results served as the basis for an international Delphi consensus process among 28 interdisciplinary experts who are members of the European Society for Radiotherapy and Oncology (ESTRO) and European Organisation for Research and Treatment of Cancer (EORTC) OligoCare consortium. Consensus was sought about risk mitigation strategies of metastases-directed SBRT combined with targeted therapy or immunotherapy; a potential need for and length of interruption to targeted therapy or immunotherapy around SBRT delivery; and potential adaptations of radiation dose and fractionation. Results of this systematic review and consensus process compile the best available evidence for safe combination of metastases-directed SBRT and targeted therapy or immunotherapy for patients with metastatic or oligometastatic cancer and aim to guide today's clinical practice and the design of future clinical trials.

Doses, fractionations, constraints for stereotactic radiotherapy

This paper describes how to select the most appropriate stereotactic radiotherapy (SRT ) dose and fractionation scheme according to lesion size and site, organs at risk (OARs) proximity and the biological effective dose. In single-dose SRT, 15-34 Gy are generally used while in fractionated SRT 30 and 75 Gy in 2-5 fractions are administered. The ICRU Report No. 91, which is specifically dedicated to SRT treatments, provided indications for dose prescription (with its definition and essential steps), dose delivery and optimal coverage which was defined as the best planning target volume coverage that can be obtained in the irradiated district. Calculation algorithms and OAR s dose constraints are provided as well as treatment planning system characteristics, suggested beam energy and multileaf collimator leaf size. Finally, parameters for irradiation geometry and plan quality are also reported.

Stereotactic radiotherapy for oligometastases in the lymph nodes

Even though systemic therapy is standard treatment for lymph node metastases, metastasis-directed stereotactic radiotherapy (SRT ) seems to be a valid option in oligometastatic patients with a low disease burden.

Positron emission tomography-computed tomography (PET-CT ) is the gold standard for assessing metastases to the lymph nodes; co-registration of PET-CT images and planning CT images are the basis for gross tumor volume (GTV ) delineation. Appropriate techniques are needed to overcome target motion. SRT schedules depend on the irradiation site, target volume and dose constraints to the organs at risk (OARs) of toxicity. Although several fractionation schemes were reported, total doses of 48–60 Gy in 4–8 fractions were proposed for mediastinal lymph node SRT, with the spinal cord, esophagus, heart and proximal bronchial tree being the dose limiting OAR s. Total doses ranged from 30 to 45 Gy, with daily fractions of 7–12 Gy for abdominal lymph nodes, with dose limiting OARs being the liver, kidneys, bowel and bladder. SRT on lymph node metastases is safe; late side effects, particularly severe, are rare.

Stereotactic body radiotherapy plus cetuximab for previously irradiated un-resectable head and neck cancer

BACKGROUND

The aim of the study was to explore the treatment outcomes and prognostic factors for patients with previously irradiated but unresectable recurrent head and neck squamous cell carcinoma (rHNSCC) treated by stereotactic body radiotherapy (SBRT) plus cetuximab at a single institute in Taiwan.

METHODS

From February 2016 to March 2019, 74 patients with previously irradiated but unresectable rHNSCC were treated with SBRT plus cetuximab. All patients received irradiation to the gross tumor and/or nodal area with 40-50 Gy in five fractions, with each fraction interval ≥ 2 days over a 2-week period by using the CyberKnife M6 machine. An¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography (PET-CT) scan was performed before treatment for treatment target delineation (n = 74) and 2 months later for response evaluation (n = 60). The median follow-up time was 9 months (range 1-36 months).

RESULTS

The treatment response rate was complete response: 25.0%, partial response: 41.7%, stable disease: 11.7%, and progressive disease: 21.7% based on the criteria of the Response Evaluation Criteria in Solid Tumors (n = 72) and complete metabolic response: 21.7%, partial metabolic response: 51.7%, stable metabolic disease: 13.3%, and progressive metabolic disease: 13.3% based on PET-CT (n = 60), respectively. The 1-/2-year overall survival (OS) and progression-free survival (PFS) rates were 42.8%/22.0% and 40.5%/19.0%, respectively. In the logistic regression model, a re-irradiation interval > 12 months was observed to be the only significant prognostic factor for a favorable treatment response. In the Cox proportional hazards model, a re-irradiation interval > 12 months and gross tumor volume (GTV) ≦ 50 ml were favorable prognostic factors of OS and PFS.

CONCLUSION

SBRT plus cetuximab provides a promising salvage strategy for those patients with previously irradiated but unresectable rHNSCC, especially those with a re-irradiation interval > 12 months or GTV ≦ 50 ml.

Predictive modeling of hypoxic head and neck cancers during fractionated radiotherapy with gold nanoparticle radiosensitization

PURPOSE

Intrinsic radioresistance and increased proliferation rates in head and neck cancers (HNCs) are associated with negative radiotherapy (RT) treatment responses. The use of gold nanoparticles (AuNPs) as radiosensitizers could enable total radiation dose reduction and lowered radiation toxicity. AuNP radiosensitization may overcome hypoxia-induced radioresistance and treatment-induced accelerated repopulation of cancer cells in HNCs, improving radiotherapy outcomes.

METHODS

Tumor control was determined by considering individual cancer cell responses in probabilistic computational simulations using HYP-RT software for clinical radiotherapy doses and fractionation schedules along with three different nanoparticle administration schedules. Antagonistic tumor hypoxia and rapid tumor regrowth due to accelerated repopulation of cancers cells were taken into consideration.

RESULTS

Simulations indicate that tumors that are conventionally uncontrollable can be controlled with AuNP radiosensitization. In simulations where the absence of AuNPs required radiotherapy doses above standard clinical prescriptions, reoccurring AuNP administration allowed for radiation dose reductions below standard clinical dose prescriptions. For example, considering a 2 Gy per fraction radiotherapy schedule, tumor control was achieved with 57.2 ± 5.1 Gy (P = <0.0001) for weekly AuNP administration and 53.0 ± 4.0 Gy (P = <0.0001) for biweekly AuNP administration compared to 69.9 ± 5.8 Gy with no radiosensitization.

CONCLUSIONS

AuNPs decreased the predicted RT total doses required to achieve tumor control via total stem cell elimination, offering an optimistic prediction and method for which hypoxia-induced and rapidly growing radioresistant tumors are treated more effectively. Outcomes are also shown to be sensitive to the RT schedule with data for hyperfractionated RT indicating the greatest benefits from radiosensitization.

Re-irradiation with Moderate Hypo-Fractionation Using Intensity Modulated Photon or Proton Radiation Therapy in Locally Recurrent Squamous Cell Carcinoma of Nasopharynx

Purpose

This study aimed to analyze the treatment outcomes of locally recurrent nasopharyngeal cancer (NPC) patients following moderate hypo-fractionation re-irradiation (re-RT).

Materials and Methods

Sixty locally recurrent NPC patients underwent hypo-fractionation re-RT. 48.3% had rT3-4, and 30.0% did keratinizing squamous cell carcinoma. Intensity-modulated radiation therapy (IMRT), with or without intensity-modulated proton therapy (IMPT), was used in 66.7% of patients.

Results

With the median follow up of 22 (2~254) months, 31 patients (51.7%) died, 38 (63.3%) developed further treatment failure, and 30 (50.0%) developed ≥Grade 3 toxicity (including seven Grade 5) at time of analysis. The 2- and 5-year rates of overall survival, local failure-free survival, and ≥Grade 3 toxicity-free survival were 57.9% and 45.8%, 64.1% and 52.5%, and 54.8% and 44.9%, respectively. In multivariate analyses, worse factors for OS were iT3-4 (p=0.010) and age at re-RT ≥53 years (p=0.003), those for LFFS were rT3-4 (p=0.022) and rN0-1 (p=0.035), and those for TFS were iT3-4 (p=0.020) and rIMRT/IMPT (p=0.030), respectively. Cumulative dose or fraction size ≥3 Gy at re-RT, however, showed no significance for OS, LFFS and TFS.

Conclusion

Current re-RT with modern RT techniques by moderate hypo-fractionation scheme seemed feasible in treating locally recurrent NPC patients.

A systematic review and practical considerations of stereotactic body radiotherapy in the treatment of head and neck cancer

OBJECTIVES

Stereotactic radiotherapy (SBRT) is gaining popularity although its use in head and neck cancer (HNC) is not well defined. The primary objective was to review the published evidence regarding the use of stereotactic radiotherapy in HNC.

METHODS

A literature search was performed by using MEDLINE and EMBASE databases for eligible studies from 2000 to 2019 and 26 relevant studies were identified.

RESULTS

Literature demonstrates a heterogeneous use of this technique with regards to patient population, primary or salvage treatment, dose fractionation regimens, outcomes and follow-up protocols. Carotid blow out syndrome is a risk as with other forms of reirradiation but alternative treatment regimens may reduce this risk.

CONCLUSION

At present there is a lack of evidence regarding SBRT as a primary treatment option for HNC and definitive answers regarding efficacy and tolerability cannot be provided but there is growing evidence that SBRT reirradiation regimens are safe and effective. In lieu of evidence from large Phase III trials, we define appropriate organ at risk constraints and prescription doses, with accurate plan summation approaches. Prospective randomised trials are warranted to validate improved treatment outcomes and acceptable treatment morbidity.

ADVANCES IN KNOWLEDGE

This article provides a comprehensive review of evidence of use of stereotactic radiotherapy in HNC site (either as a primary treatment or as reirradiation). We also provide an evidence-based approach to the implementation and practical consideration of stereotactic radiotherapy in HNC.

In silico modeling of cellular probabilistic nanoparticle radiosensitization in head and neck cancers

Background: The use of gold nanoparticles (AuNPs) as radiosensitizers may offer a new approach in the treatment of head and neck cancers; minimizing treatment-associated toxicities and improving patient outcomes. AuNPs promote localized dose deposition; permitting improved local control and/or dose reduction. Aim: This work aimed to address the theoretical optimization of radiation doses, fractionation and nanoparticle injection schedules to maximize therapeutic benefits. Materials & methods: Probabilistic nanoparticle sensitization factors were incorporated into the individual cell-based HYP-RT computer model of tumor growth and radiotherapy. Results: Total dose outcomes across all radiation therapy treatment regimens were found to be significantly reduced with the presence of AuNPs, with bi-weekly injections showing the most decrease. Conclusion: Outcomes suggest the need for regular AuNP administration to permit effective radiosensitization.

The feasibility and efficacy of new SBRT technique HyperArc for recurrent nasopharyngeal carcinoma: noncoplanar cone-based robotic system vs. noncoplanar high-definition MLC based Linac system

The purpose of this study was to evaluate the feasibility and efficacy of HyperArc (HA) for recurrent nasopharyngeal cancer (NPC) by comparing it with the CyberKnife system (CK). Fifteen patients with recurrent nasopharyngeal cancer who were treated using the noncoplanar cone-based robotic CK system were enrolled. CK was delivered with a median dose of 37.5 Gy in 5 fractions. The delivered CK treatment plans were the sources for the corresponding homogeneous HA (HA-H) and inhomogeneous HA (HA-IH) plans. The HA-H plans were generated to meet the corresponding treatment plan criteria for the CK plans. The HA-IH plans were designed to emulate the corresponding inhomogeneous CK isodose distributions. These three SBRT treatment plans were compared with target coverage, sparing of organs at risk (OARs), and dose distribution metrics. The HA-H and HA-IH plans consistently exhibited CTV and PTV coverage levels similar or better to those of the CK plans but significantly reduced the dose to OARs. Using the HA techniques (both HA-H and HA-IH plans), the mean maximal doses to the spinal cord, brainstem, optic nerves, and optic chiasm were reduced by approximately 60%, compared to the CK plans. The high dose spillage, conformity, and homogeneity indices of the HA-H plans were significantly better than those of the CK plans. The HA-IH plans showed faster dose falloff and similar conformity of the HA-H plans and dose heterogeneity of the CK plans. Here we demonstrated the HA treatment plan system for recurrent NPC is feasible, either homogeneous or inhomogeneous delivery. Excellent sparing of OARs and dosimetric distribution and very efficient delivery make HA an attractive SBRT technique for recurrent NPC treatment.

Stereotactic Body Radiotherapy Treatment for Recurrent, Previously Irradiated Head and Neck Cancer

Purpose:

Locally recurrent, previously irradiated primary head and neck tumors have historically been associated with poor outcomes. Stereotactic body radiation therapy has emerged as a feasible and promising treatment option for tumor recurrence, particularly in nonsurgical candidates. This study aimed to assess the associated outcomes of stereotactic body radiation therapy used in this setting.

Methods:

Retrospective analysis of a prospectively collected database of 25 patients treated with CyberKnife for unresectable, recurrent head and neck cancer in a previously irradiated field. The primary end points evaluated were rates of survival, tumor control, and treatment-related toxicities.

Results:

Median survival of the study population was 7.5 months (range, 1.5-47.0 months). Median survival of the 20 (80%) patients who were treated with curative purpose was 8.3 months. One-year overall survival rate for the entire population was 32%. The respective 1-year and 2-year survival rates for the curative subcohort were 40% and 20%, respectively. Local and locoregional failure occurred in 8 (32%) and 7 (28%) patients, respectively. Low severe acute (4%) and late (6%) treatment-related toxicity rates were observed. No grade 4 or 5 toxicities were observed.

Conclusion:

Stereotactic body radiation therapy is a viable treatment option for patients with unresectable, recurrent head and neck cancer. Significant tumor control rates are achievable with minimal severe toxicity. Although perhaps associated with patient selection and a heterogeneous sample, overall survival of stereotactic body radiation therapy outcomes appears unfavorable.

Toxicity of concurrent stereotactic radiotherapy and targeted therapy or immunotherapy: A systematic review

BACKGROUND AND PURPOSE

Both stereotactic radiotherapy (SRT) and immune- or targeted therapy play an increasingly important role in personalized treatment of metastatic disease. Concurrent application of both therapies is rapidly expanding in daily clinical practice. In this systematic review we summarize severe toxicity observed after concurrent treatment.

MATERIAL AND METHODS

PubMed and EMBASE databases were searched for English literature published up to April 2016 using keywords "radiosurgery", "local ablative therapy", "gamma knife" and "stereotactic", combined with "bevacizumab", "cetuximab", "crizotinib", "erlotinib", "gefitinib", "ipilimumab", "lapatinib", "sorafenib", "sunitinib", "trastuzumab", "vemurafenib", "PLX4032", "panitumumab", "nivolumab", "pembrolizumab", "alectinib", "ceritinib", "dabrafenib", "trametinib", "BRAF", "TKI", "MEK", "PD1", "EGFR", "CTLA-4" or "ALK". Studies performing SRT during or within 30days of targeted/immunotherapy, reporting severe (⩾Grade 3) toxicity were included.

RESULTS

Concurrent treatment is mostly well tolerated in cranial SRT, but high rates of severe toxicity were observed for the combination with BRAF-inhibitors. The relatively scarce literature on extra-cranial SRT shows a potential risk of increased toxicity when SRT is combined with EGFR-targeting tyrosine kinase inhibitors and bevacizumab, which was not observed for cranial SRT.

CONCLUSIONS

This review gives a best-possible overview of current knowledge and its limitations and underlines the need for a timely generation of stronger evidence in this rapidly expanding field.