Local recurrences after curative IMRT for HNSCC: Effect of different GTV to high-dose CTV margins

A systematic review and proportional meta-analysis of image-based pattern of loco-regional failure analyses outcomes in head and neck squamous cell carcinoma

BACKGROUND AND PURPOSE

The prognosis following loco-regional failure after primary radiotherapy (RT) for head and neck squamous cell carcinoma (HNSCC) is poor. The hypothesis that most failures occur as a consequence of tumor radioresistance, can be evaluated by proxy as the proportion of failures that occur in the high-dose region. Several studies have investigated possible reasons for treatment failure by an image-based pattern of failure analyses (POF), comparing the initial planning CT scan with a scan conducted upon failure. The aim of the present systematic review and meta-analysis was to evaluate the proportion of failures that occurred in the high-dose region of all analyzed failures.

MATERIALS AND METHODS

A systematic database search from 2000 to 2023, was performed for studies including results from image-based loco-regional POF, regardless of the method, after primary RT for HNSCC. Proportions of volumetrically in-field (opposed to marginal or outfield) failures, point of origin-based inside high-dose targets, or covered by curative doses for both the number of patients and the number of failure sites were analyzed in proportional meta-analyses. The review was registered at Prospero (CRD42023412545).

RESULTS

Out of 56 included studies, accumulated image-based POF results were available from 1,161 patients and 658 individual failure sites. The majority of patients had in-field failures in volumetric-based studies (84 % (95 % CI: 77;90)), inside failures in point of origin-based studies (82 % (95% CI:61;85)) or failures covered by 95 % of dose prescribed to CTV1 (84 % (95% CI:69;95)). A trend toward increasing proportions of non-high-dose failures in more recently treated patients was observed.

CONCLUSION

Most loco-regional failures for patients treated with primary RT for HNSCC are related to the high-dose volume. Therefore, a focus on biomarkers predicting individual tumor radiosensitivity is warranted to enable individualized treatment intensification to increase loco-regional control.

A probabilistic evaluation of the Dutch robustness and model-based selection protocols for Head-and-Neck IMPT: A multi-institutional study

BACKGROUND AND PURPOSE

In the Netherlands, 2 protocols have been standardized for PT among the 3 proton centers: a robustness evaluation (RE) to ensure adequate CTV dose and a model-based selection (MBS) approach for IMPT patient-selection. This multi-institutional study investigates (i) inter-patient and inter-center variation of target dose from the RE protocol and (ii) the robustness of the MBS protocol against treatment errors for a cohort of head-and-neck cancer (HNC) patients treated in the 3 Dutch proton centers.

MATERIALS AND METHODS

Clinical treatment plans of 100 HNC patients were evaluated. Polynomial Chaos Expansion (PCE) was used to perform a comprehensive robustness evaluation per plan, enabling the probabilistic evaluation of 100,000 complete fractionated treatments. PCE allowed to derive scenario distributions of clinically relevant dosimetric parameters to assess CTV dose (D99.8%/D0.2%, based on a prior photon plan calibration) and tumour control probabilities (TCP) as well as the evaluation of the dose to OARs and normal tissue complication probabilities (NTCP) per center.

RESULTS

For the CTV70.00, doses from the RE protocol were consistent with the clinical plan evaluation metrics used in the 3 centers. For the CTV54.25, D99.8% were consistent with the clinical plan evaluation metrics at center 1 and 2 while, for center 3, a reduction of 1 GyRBE was found on average. This difference did not impact modelled TCP at center 3. Differences between expected and nominal NTCP were below 0.3 percentage point for most patients.

CONCLUSION

The standardization of the RE and MBS protocol lead to comparable results in terms of TCP and the NTCPs. Still, significant inter-patient and inter-center variation in dosimetric parameters remained due to clinical practice differences at each institution. The MBS approach is a robust protocol to qualify patients for PT.

Comparison of 3-year local control using DAHANCA radiotherapy guidelines before and after implementation of five millimetres geometrical GTV to high-dose CTV margin

INTRODUCTION

Treatment planning using a five-millimetre geometrical margin from GTV to high-dose CTV (CTV1) has been used in DAHANCA treatment centres since 2013. We aimed to evaluate changes in CTV1 volumes, local control (LC), and recurrence pattern after the implementation of five-millimetre geometrical margins nationally.

MATERIALS AND METHODS

1,948 patients with pharyngeal, and laryngeal squamous cell carcinomas completed definitive IMRT-based treatment in 2010-2012 and 2013-2015 in three centres. The patient-specific margin was calculated as median surface distance from primary tumour GTV (GTV-T) to CTV1. Radiologically verified local recurrences were analysed using a centre of mass (COM) of the delineated recurrence volume, measuring the shortest distance between COM to GTV-T and CTV1 boundaries.

RESULTS

Median GTV-CTV1 was 0.9 (0.0-0.97) and 0.47 cm (0.4-0.5) for 2010-2012 and 2013-2015, respectively. Median CTV1 changed in three centres from 76, 28, 42 cm3 to 61, 53, 62 cm3 for 2010-2012 and 2013-2015, respectively. Local failures occurred at 247 patients during first three years after radiotherapy. The 3-year LC rate for 2010-2012 and 2013-2015 was 0.84 and 0.87 (p = 0.06). Out of 146 radiology-verified analysable local recurrences, 102 (69.9%) were inside the CTV1. In 74.6% and 91% of cases, the LRs were covered by 95% isodose in 2010-2012 and 2013-2015, respectively.

CONCLUSION

DAHANCA radiotherapy guidelines based on a geometrically generated isotropic CTV1 margin led to less variation in treatment volumes and between centres than previous guidelines. The transition towards consensus GTV-CTV1 margins did not influence local tumour control. The majority of local recurrences were inside CTV1 and covered by the prescription dose.

High-dose loco-regional pattern of failure after primary radiotherapy in p16 positive and negative head and neck squamous cell carcinoma - A DAHANCA 19 study

Introduction

Patients with failure after primary radiotherapy (RT) for head and neck squamous cell carcinoma (HNSCC) have a poor prognosis. This study investigates pattern of failure after primary curatively intended IMRT in a randomized controlled trial in relation to HPV/p16 status.

Material and methods

Patients with HNSCC of the oral cavity, oropharynx (OPSCC), hypopharynx or larynx were treated with primary curative IMRT (+/-cisplatin) and concomitant nimorazole between 2007 and 12. Of 608 patients, 151 had loco-regional failure within five years, from whom 130 pairs of scans (planning-CT and diagnostic failure scan) were collected and deformably co-registered. Point of origin-based pattern of failure analysis was conducted, including distance to CTV1 and GTV, and estimated dose coverage of the point of origin.

Results

Of 130 patients with pairs of scans, 104 (80 %) had at least one local or regional failure site covered by 95 % of prescribed dose and 87 (67 %) of the failures had point of origin within the high-dose CTV (CTV1). Of failures from primary p16 + OPSCC, the majority of both mucosal (84 %) and nodal (61 %) failures were covered by curative doses. For p16- tumors (oral cavity, OPSCC p16neg, hypopharynx and larynx), 75 % of mucosal and 66 % of nodal failures were high-dose failures.

Conclusion

Radioresistance is the primary cause of failure after RT for HNSCC irrespective of HPV/p16 status. Thus, focus on predictors for the response to RT is warranted to identify patients with higher risk of high-dose failure that might benefit from intensified treatment regimens.

Tumor volume and cancer stem cell expression as prognostic markers for high-dose loco-regional failure in head and neck squamous cell carcinoma - A DAHANCA 19 study

BACKGROUND AND PURPOSE

Reliable and accessible biomarkers for patients with Head and Neck Squamous Cell Carcinoma (HNSCC) are warranted for biologically driven radiotherapy (RT). This study aimed to investigate the prognostic value of putative cancer stem cell (CSC) markers, hypoxia, and tumor volume using loco-regional high-dose failure (HDF) as endpoint.

MATERIALS AND METHODS

Tumor tissue was retrieved from patients treated with primary chemo-(C-)RT and nimorazole for HNSCC in the Danish Head and Neck Cancer Study Group (DAHANCA) 19 study. Tumor volume, hypoxic classification, and expression of CSC markers CD44, SLC3A2, and MET were analyzed. For patients with eligible data on all parameters (n = 340), the risk of HDF following primary chemo-(C-)RT were analyzed by these biomarkers as a whole and stratified for p16-positive oropharynx (p16 + OPSCC) vs p16-negative (p16-) tumors (oral cavity, p16- oropharynx, hypopharynx and larynx).

RESULTS

Higher risk of HDF was seen for patients with larger primary and nodal volume (>25 cm3, Hazard Ratio (HR): 3.00 [95 % CI: 1.73-5.18]), high SLC3A2 (HR: 2.99 [1.28-6.99]), CD44 (>30 % positive, HR: 2.29 [1.05-5.00]), and p16- tumors (HR: 2.53 [1.05-6.11]). p16- tumors had a higher CSC marker expression than p16 + OPSCC. The factors associated with the highest risk of HDF were larger volume (HR: 3.29 [1.79-6.04]) for p16- tumors (n = 178) and high SLC3A2 (HR: 6.19 [1.58-24.23]) for p16 + OPSCC (n = 162).

CONCLUSION

Tumor volume, p16, and CSC markers are potential biomarkers for HDF for patients with HNSCC treated with (C-)RT. Lower expression of CSC in p16 + OPSCC may contribute to better tumor control.

Differences in geometric patterns of failure in human papillomavirus (HPV)-associated and HPV-non-associated oropharyngeal cancer after definitive radiotherapy

INTRODUCTION

The aim of this study was to evaluate and compare the spatial pattern of locoregional recurrences in patients diagnosed with HPV-associated and HPV-non-associated oropharyngeal SCC (OPSCC) treated with definitive radiotherapy.

METHODS AND MATERIALS

Patients who had locoregional recurrence following definitive intensity-modulated radiation therapy were identified at a single tertiary institution. Target volumes were delineated according to the latest consensus international guidelines. Recurrences were classified into five categories based on radiotherapy dose distribution and target volume, using a previously validated methodology; type A (central high dose), type B (peripheral high dose), type C (central elective dose), type D (peripheral elective dose), and type E (extraneous dose). The types of failure were compared between p16-positive and p16-negative tumors using the Pearson chi-square test.

RESULTS

Fifty-eight locoregional recurrences were observed in 36 patients. The majority of recurrences were in nodal locations (66%, 38/58). Among these, 34 (59%) were classified as type A, 6 (10%) as type B, 9 (15%) as type C, 5 (9%) as type D, and 4 (7%) as type E failure. A significant difference was found in the types of failure between p16-positive and p16-negative tumors (X2 9.52, p = 0.044). p16-negative tumors were more likely to have recurrences in a peripheral location compared to p16-positive tumors (32% vs. 7%). p16-positive tumor were more likely to have extraneous recurrences (17% vs. 0%).

CONCLUSION

Our study results identified a significant difference in patterns of locoregional failure among patients diagnosed with oropharyngeal cancer following consensus-based tumor delineation and modern radiotherapy. Further confirmatory pattern of failure studies are required to enable greater individualization of radiotherapy for patients diagnosed with oropharyngeal malignancy in the future.

Impact of consensus guidelines on delineation of primary tumor clinical target volume (CTVp) for head and neck cancer: Results of a national review project

BACKGROUND AND PURPOSE

A significant interobserver variability (IOV) for clinical target volume of the primary tumor (CTVp) delineation was shown in a previous national review project. Since then, international expert consensus guidelines (CG) for the delineation of CTVp were published. The aim of this follow-up study was to 1) objectify the extent of implementation of the CG, 2) assess its impact on delineation quality and consistency, 3) identify any remaining ambiguities.

MATERIALS AND METHODS

All Belgian RT departments were invited to complete an online survey and submit CTVp for 5 reference cases. Organs at risk and GTV of the primary tumor were predefined. Margins, volumes, IOV between all participating centers (IOVall) and IOV compared to a reference consensus delineation (IOVref) were calculated and compared to the previous analysis. A qualitative analysis was performed assessing the correct interpretation of the CG for each case.

RESULTS

17 RT centers completed both survey and delineations, of which 88% had implemented CG. Median DSCref for CTVp_total was 0.80-0.92. IOVall and IOVref improved significantly for the centers following CG (p = 0.005). IOVref for CTVp_high was small with a DSC higher than 0.90 for all cases. A significant volume decrease for the CTVp receiving 70 Gy was observed. Interpretation of CG was more accurate for (supra)glottic carcinoma. 60% of the radiation oncologists thinks clarification of CG is indicated.

CONCLUSION

Implementation of consensus guidelines for CTVp delineation is already fairly advanced on a national level, resulting in significantly increased delineation uniformity. The accompanying substantial decrease of CTV receiving high dose RT calls for caution and correct interpretation of CG. Clarification of the existing guidelines seems appropriate especially for oropharyngeal and hypopharyngeal carcinoma.

Assessment of residual geometrical errors of clinical target volumes and their impact on dose accumulation for head and neck radiotherapy

PURPOSE

To assess the residual geometrical errors (dr) and their impact on the clinical target volumes (CTV) dose coverage for head and neck cancer (HNC) proton therapy patients.

METHODS

We analysed 28 HNC patients treated with 70 Gy (RBE) and 54.25 Gy (RBE) to the therapeutic CTV70 and prophylactic CTV54.25, respectively. Daily cone beam CTs were converted to high quality synthetic CTs (sCTs). The CTVs from the nominal CT were propagated to the corresponding sCTs using a hybrid deformable image registration (propagated CTVs) in RayStation 11B. For 11 patients, all propagated CTVs were reviewed by our HNC radiation oncologist (physician corrected CTVs). The residual geometrical error dr was quantified as a function of the daily CTVs volume overlap with the nominal plan CTV. The errors dr(propagated CTVs) and dr(physician corrected CTVs) and the difference in dice similarity coefficients (ΔDSC) were determined. Using clinical plans, dose coverage and the tumor control probability (TCP) for the nominal, accumulated and voxel-wise minimum scenarios were determined.

RESULTS

The difference in the residual geometrical error dr (propagated CTVs - physician corrected CTVs) and mean DSC (|ΔDSC|mean) were minor: Δdr(CTV70) = 0.16 mm, Δdr(CTV54.25) = 0.26 mm, |ΔDSC|mean < 0.9%. For all 28 patients, dr(CTV70) = 1.91 mm and dr(CTV54.25) = 1.90 mm. However, CTV54.25 above and below the cricoid cartilage differed substantially (1.00 mm c.f. 3.93 mm). The CTV54.25 coverage below the cricoid was then almost always lower, although the TCP of the accumulated dose was higher than the TCP of the voxel-wise minimum dose.

CONCLUSIONS

Setup uncertainty setting of 2 mm is possible. The feasibility of using propagated CTVs for error determination is demonstrated.

A national repository of complete radiotherapy plans: design, Results, and experiences

BACKGROUND

Previously, many radiotherapy (RT) trials were based on a few selected dose measures. Many research questions, however, rely on access to the complete dose information. To support such access, a national RT plan database was created. The system focuses on data security, ease of use, and re-use of data. This article reports on the development and structure, and the functionality and experience of this national database.

METHODS AND MATERIALS

A system based on the DICOM-RT standard, DcmCollab, was implemented with direct connections to all Danish RT centres. Data is segregated into any number of collaboration projects. User access to the system is provided through a web interface. The database has a finely defined access permission model to support legal requirements.

RESULTS

Currently, data for more than 14,000 patients have been submitted to the system, and more than 50 research projects are registered. The system is used for data collection, trial quality assurance, and audit data set generation.Users reported that the process of submitting data, waiting for it to be processed, and then manually attaching it to a project was resource intensive. This was accommodated with the introduction of triggering features, eliminating much of the need for users to manage data manually. Many other features, including structure name mapping, RT plan viewer, and the Audit Tool were developed based on user input.

CONCLUSION

The DcmCollab system has provided an efficient means to collect and access complete datasets for multi-centre RT research. This stands in contrast with previous methods of collecting RT data in multi-centre settings, where only singular data points were manually reported. To accommodate the evolving legal environment, DcmCollab has been defined as a 'data processor', meaning that it is a tool for other research projects to use rather than a research project in and of itself.

The Metabolic Footprint of Systemic Effects in the Blood Caused by Radiotherapy and Inflammatory Conditions: A Systematic Review

Response to radiotherapy (RT) includes tissue toxicity, which may involve inflammatory reactions. We aimed to compare changes in metabolic patterns induced at the systemic level by radiation and inflammation itself. Patients treated with RT due to head and neck cancer and patients with inflammation-related diseases located in the corresponding anatomical regions were selected. PubMed and Web of Science databases were searched from 1 January 2000 to 10 August 2023. Twenty-five relevant studies where serum/plasma metabolic profiles were analyzed using different metabolomics approaches were identified. The studies showed different metabolic patterns of acute and chronic inflammatory diseases, yet changes in metabolites linked to the urea cycle and metabolism of arginine and proline were common features of both conditions. Although the reviewed reports showed only a few specific metabolites common for early RT response and inflammatory diseases, partly due to differences in metabolomics approaches, several common metabolic pathways linked to metabolites affected by radiation and inflammation were revealed. They included pathways involved in energy metabolism (e.g., metabolism of ketone bodies, mitochondrial electron transport chain, Warburg effect, citric acid cycle, urea cycle) and metabolism of certain amino acids (Arg, Pro, Gly, Ser, Met, Ala, Glu) and lipids (glycerolipids, branched-chain fatty acids). However, metabolites common for RT and inflammation-related diseases could show opposite patterns of changes. This could be exemplified by the lysophosphatidylcholine to phosphatidylcholine ratio (LPC/PC) that increased during chronic inflammation and decreased during the early phase of response to RT. One should be aware of dynamic metabolic changes during different phases of response to radiation, which involve increased levels of LPC in later phases. Hence, metabolomics studies that would address molecular features of both types of biological responses using comparable analytical and clinical approaches are needed to unravel the complexities of these phenomena, ultimately contributing to a deeper understanding of their impact on biological systems.

DOSE AND VOLUME DE-ESCALATION OF RADIOTHERAPY IN HEAD AND NECK CANCER

Radiotherapy plays a key role in the treatment of head and neck cancer. However, irradiation of the head and neck region is associated with high rates of acute and chronic toxicity. Technological advances have led to better visualisation of target volumes and critical structures and improved dose conformality in the treatment volume. Despite this, acute toxicity has not been substantially reduced and late toxicity has a significant impact on patients' quality of life. The greater radiosensitivity of tumours associated with the HPV and the development of new imaging techniques have encouraged research into new deintensified strategies to reduce the side effects of radiotherapy. The aim of this paper is to review the literature on the strategies of de-escalated treatment in dose and/or volume in head and neck cancer.

Recurrence prediction with local binary pattern-based dosiomics in patients with head and neck squamous cell carcinoma

We investigated an approach for predicting recurrence after radiation therapy using local binary pattern (LBP)-based dosiomics in patients with head and neck squamous cell carcinoma (HNSCC). Recurrence/non-recurrence data were collected from 131 patients after intensity-modulated radiation therapy. The cases were divided into training (80%) and test (20%) datasets. A total of 327 dosiomics features, including cold spot volume, first-order features, and texture features, were extracted from the original dose distribution (ODD) and LBP on gross tumor volume, clinical target volume, and planning target volume. The CoxNet algorithm was employed in the training dataset for feature selection and dosiomics signature construction. Based on a dosiomics score (DS)-based Cox proportional hazard model, two recurrence prediction models (DS_ODD and DS_LBP) were constructed using the ODD and LBP dosiomics features. These models were used to evaluate the overall adequacy of the recurrence prediction using the concordance index (CI), and the prediction performance was assessed based on the accuracy and area under the receiver operating characteristic curve (AUC). The CIs for the test dataset were 0.71 and 0.76 for DS_ODD and DS_LBP, respectively. The accuracy and AUC for the test dataset were 0.71 and 0.76 for the DS_ODD model and 0.79 and 0.81 for the DS_LBP model, respectively. LBP-based dosiomics models may be more accurate in predicting recurrence after radiation therapy in patients with HNSCC.

Why subclinical involvement is prescribed the same high dose as gross tumor volume: A study on high-dose clinical target volume in intensity-modulated radiotherapy plan of nasopharyngeal carcinoma

BACKGROUND

Most nasopharyngeal carcinoma (NPC) protocols define primary gross tumor volume (GTVnx) plus a range from 2 to 5 mm as the high-dose clinical target volume (hd-CTV). However, in China, hd-CTV is defined as GTVnx plus 0 mm.

METHODS

A total of 40 patients with newly diagnosed nonmetastatic NPC (T1-T4 ten cases each) treated with IMRT were consecutively enrolled. Real and virtual treatment plans were designed according to the definitions of hd-CTV recommended by China and Radiation Therapy Oncology Group (RTOG), respectively.

RESULTS

The hd-CTV in China was significantly smaller than that of RTOG. Exposure doses to 5 mm subclinical involvement and OARs as well as NTCP in the China treatment plan were significantly lower than those of RTOG.

CONCLUSION

It could be recommended to divide the hd-CTV into GTV and subclinical target volume and to prescribe different doses for the GTV and subclinical involvement in the IMRT plan of NPC.

Gross tumor volume margin and local control in p16-positive oropharynx cancer patients treated with intensity modulated proton therapy

BACKGROUND

To determine if the extent of high-dose gross tumor volume (GTV) to clinical target volume (CTV) expansion is associated with local control in patients with p16-positive oropharynx cancer (p16+ OPC) treated with definitive intensity modulated proton therapy (IMPT).

METHODS

We performed a retrospective analysis of patients with p16+ OPC treated with IMPT at a single institution between 2016 and 2021. Patients with a pre-treatment PET-CT and restaging PET-CT within 4 months following completion of IMPT were analyzed.

RESULTS

Sixty patients were included for analysis with a median follow-up of 17 months. The median GTV to CTV expansion was 5 mm (IQR: 2 mm). Thirty-three percent of patients (20 of 60) did not have a GTV to CTV expansion. There was one local failure within the expansion group (3%).

CONCLUSION

Excellent local control was achieved using IMPT for p16+ OPC independent of GTV expansion. IMPT with minimal target expansions represent a potential harm-minimization technique for p16-positive oropharynx cancer.

Patient anatomy-specific trade-offs between sub-clinical disease coverage and normal tissue dose reduction in head-and-neck cancer

PURPOSE

Risk of subclinical disease decreases with increasing distance from the GTV in head- and-neck squamous cell carcinoma (HNSCC). Depending on individual patient anatomy, OAR sparing could be improved by reducing target coverage in regions with low risk of subclinical spread. Using automated multi-criteria optimization, we investigate patient-specific optimal trade-offs between target periphery coverage and OAR sparing.

METHODS

VMAT plans for 39 HNSCC patients were retrospectively created following our clinical three-target-level protocol: high-risk (PTV1), intermediate-risk (PTV2, 5 mm expansion from PTV1), and elective (PTV3). A baseline plan fulfilling clinical constraints (D 99 % ≥95 % for all PTVs) was compared to three plans with reduced PTV2 coverage (goals: PTV2 D 99 % ≥90 % or 85 %, or no PTV2) at the outer edge of PTV2. Plans were compared on PTV D 99 %, OAR D mean, and NTCP (xerostomia/dysphagia).

RESULTS

Trade-offs between PTV2 coverage and OAR doses varied considerably between patients. For plans with PTV2 D 99 % -goal 90 %, median PTV2 D 99 % was 91.5 % resulting in xerostomia (≥grade 4) and dysphagia (≥grade 2) NTCP decrease of median [maximum] 1.9 % [5.3 %] and 1.1 % [4.1 %], respectively, compared to nominal PTV2 D 99 % -goal 95 %. For PTV2 D 99 % -goal 85 % median PTV D 99 % was 87 % with NTCP improvements of 4.6 % [9.9 %] and 1.5 % [5.4 %]. For no-margin plans, PTV2 D 99 % decreased to 83.3 % with NTCP reductions of 5.1 % [10.2 %] and 1.4 % [6.1 %].

CONCLUSION

Clinically relevant, patient-specific reductions in OARs and NTCP were observed at limited cost in target under-coverage at the outermost PTV edge. Given the observed inter-patient variations, individual evaluation is warranted to determine whether trade- offs would benefit a specific patient.

Delineation uncertainties of tumour volumes on MRI of head and neck cancer patients

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Role of target delineation uncertainties in head and neck cancer patients.

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Knowing contouring variations for MRI allows better adaptation of MRLinac for H&N cancers.

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An interobserver variation for GTV among 8 observers was below 2 mm using MRI.

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Variability between observers might improve using other imaging modalities.

Background

During the last decade, radiotherapy using MR Linac has gone from research to clinical implementation for different cancer locations. For head and neck cancer (HNC), target delineation based only on MR images is not yet standard, and the utilisation of MRI instead of PET/CT in radiotherapy planning is not well established. We aimed to analyse the inter-observer variation (IOV) in delineating GTV (gross tumour volume) on MR images only for patients with HNC.

Material/methods

32 HNC patients from two independent departments were included. Four clinical oncologists from Denmark and four radiation oncologists from Australia had independently contoured primary tumour GTVs (GTV-T) and nodal GTVs (GTV-N) on T2-weighted MR images obtained at the time of treatment planning. Observers were provided with sets of images, delineation guidelines and patient synopsis. Simultaneous truth and performance level estimation (STAPLE) reference volumes were generated for each structure using all observer contours. The IOV was assessed using the DICE Similarity Coefficient (DSC) and mean absolute surface distance (MASD).

Results

32 GTV-Ts and 68 GTV-Ns were contoured per observer. The median MASD for GTV-Ts and GTV-Ns across all patients was 0.17 cm (range 0.08–0.39 cm) and 0.07 cm (range 0.04–0.33 cm), respectively. Median DSC relative to a STAPLE volume for GTV-Ts and GTV-Ns across all patients were 0.73 and 0.76, respectively. A significant correlation was seen between median DSCs and median volumes of GTV-Ts (Spearman correlation coefficient 0.76, p < 0.001) and of GTV-Ns (Spearman correlation coefficient 0.55, p < 0.001).

Conclusion

Contouring GTVs in patients with HNC on MRI showed that the median IOV for GTV-T and GTV-N was below 2 mm, based on observes from two separate radiation departments. However, there are still specific regions in tumours that are difficult to resolve as either malignant tissue or oedema that potentially could be improved by further training in MR-only delineation.

Co-registration of radiotherapy planning and recurrence scans with different imaging modalities in head and neck cancer

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Head and neck magnetic resonance imaging and computed tomography co-registration.

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Validation of planning and recurrence scan co-registration separated in time.

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Mean distances to agreement for regions of interest/normal tissue were tolerable.

MRI (magnetic resonance imaging) scans are frequently used in follow-up after radiotherapy for head and neck cancer. With the overall aim of enabling MRI-based pattern of failure analysis, this study evaluated the accuracy of recurrence MRI (rMRI) deformable co-registration with planning CT (computed tomography)-scans (pCT). Uncertainty of anatomical changes between pCT and rMRI was assessed by similarity metric analyses of co-registered image structures from 19 patients. Average mean distance to agreement and Dice similarity coefficient performed adequately. Our findings provide proof of concept for reliable co-registration of pCT and rMRI months to years apart for MRI-based pattern of failure analysis.

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.

Reducing target volume in definitive radiotherapy for human papillomavirus-associated tonsil cancer

BACKGROUND

To evaluate the efficacy and safety of reducing target volume in definitive radiotherapy for HPV-associated tonsil cancer.

METHODS

A single-institution cohort of 90 patients with human papillomavirus (HPV)-associated tonsil cancer who received definitive radiotherapy with a 5-mm expansion from the gross tumor volume to clinical target volume between 2008 and 2019 were included. The overlapping volume of initial planning target volume and the recurrent tumor was calculated and categorized as one of three failure types: in-field: ≥95%; marginal-field: 50%-94%; and out-field: <50%.

RESULTS

With a median follow-up of 59.4 months, the 3-year and 5-year local control rates were 94.4% and 92.8%, respectively. A total of seven local failures were identified, of which 4 (4.4%) were in-field, 2 (2.2%) were marginal-field, and 1 (1.1%) was out-field. Grade 3 acute and late toxicities developed in 30 (33.3%) and 5 (5.6%) patients, respectively.

CONCLUSIONS

Reducing target volume could be an alternative option for selected patients with HPV-associated tonsil cancer.

Defining high-risk elective contralateral neck radiation volumes for oropharynx cancer

BACKGROUND

To define the location of the initial contralateral lymph node (LN) metastasis in patients with oropharynx cancer.

METHODS

The location of the LN centroids from patients with oropharynx cancer and a single radiographically positive contralateral LN was defined. A clinical target volume (CTV) inclusive of all LN centroids was created, and its impact on dose to organs at risk was assessed.

RESULTS

We identified 55 patients of which 49/55 had a single contralateral LN in level IIA, 4/55 in level III, 1/55 in level IIB, and 1/55 in the retropharynx. Mean radiation dose to the contralateral parotid gland was 15.1 and 21.0 Gy, (p <0.001) using the modeled high-risk elective CTV and a consensus CTV, respectively.

CONCLUSIONS

We present a systematic approach for identifying the contralateral nodal regions at highest risk of harboring subclinical disease in patients with oropharynx cancer that warrants prospective clinical study.

Target coverage and local recurrences after radiotherapy for sinonasal cancer in Denmark 2008-2015. A DAHANCA study

PURPOSE

The study aimed to investigate the pattern of failure and describe compromises in the definition and coverage of the target for patients treated with curatively intended radiotherapy (RT) for sinonasal cancer (SNC).

METHODS AND MATERIAL

Patients treated with curatively intended RT in 2008-2015 in Denmark for SNC were eligible for the retrospective cohort study. Information regarding diagnosis and treatment was retrieved from the national database of the Danish Head and Neck Cancer Group (DAHANCA). Imaging from the diagnosis of recurrences was collected, and the point of origin (PO) of the recurrent tumour was estimated. All treatment plans were collected and reviewed with the focus on target coverage, manual modifications of target volumes, and dose to organs at risk (OARs) above defined constraints.

RESULTS

A total of 184 patients were included in the analysis, and 76 (41%) relapsed. The majority of recurrences involved T-site (76%). Recurrence imaging of 39 patients was evaluated, and PO was established. Twenty-nine POs (74%) were located within the CTV, and the minimum dose to the PO was median 64.1 Gy (3.1-70.7). The criteria for target coverage (V95%) was not met in 89/184 (48%) of the CTV and 131/184 (71%) of the PTV. A total of 24% of CTVs had been manually modified to spare OARs of high-dose irradiation. No difference in target volume modifications was observed between patients who suffered recurrence and patients with lasting remission.

CONCLUSION

The majority of relapses after radical treatment of SNC were located in the T-site (the primary tumour site). Multiple compromises with regards to target coverage and tolerance levels for OARs in the sinonasal region, as defined from RT guidelines, were taken. No common practice in this respect could be derived from the study.

Telehealth in Multidisciplinary Target Delineation for Radiotherapy During the COVID-19 Pandemic. A Review and a Case

Like all other medical specialties, radiotherapy has been deeply influenced by the COVID-19 pandemic. The pandemic has had severe influence on the entire patient trajectory in oncology, from diagnosis to treatment and follow-up. Many examples of how to deal with patient and staff safety, shortness of staff and other resources and the quest to continue high-quality, evidence-based treatment have been presented. The use of telemedicine and telehealth is frequently presented as a part of the solution to overcome these challenges. Some of the available presented solutions will only apply in an acute, local setting, whereas others might inspire the community to improve quality and cost-effectiveness of radiotherapy as well as knowledge sharing in the future. Some of the unresolved issues in many of the available technical solutions are related to data security and public regulation, for example, GDPR (General Data Protection Regulation) in the EU and HIPAA compliance (Health Insurance Portability and Accountability Act) in the USA. Using a solution that involves a supplier's server in a non-EU country is problematic within the EU. In this paper we shortly review the influence of COVID-19 on radiotherapy. We describe some of the possible solutions for telehealth in target delineation - a crucial part of high-quality radiotherapy, which often requires multidisciplinary effort, hands-on corporation, and high-quality multimodal imaging. Hereafter, our own technical solution will be presented as a case.

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.

Imaging of Complications of Chemoradiation

Chemoradiation for head and neck cancer is associated with a variety of early and late complications. Toxicities may affect the aero-digestive tract (mucositis, salivary gland injury), regional osseous and cartilaginous structures (osteoradionecrosis (ORN) and chondronecrosis), vasculature (progressive radiation vasculopathy and carotid blow out syndromes), and neural structures (optic neuritis, myelitis, and brain injury). These may be difficult to distinguish from tumor recurrence on imaging, and may necessitate the use of advanced MRI and molecular imaging techniques to reach the correct diagnosis. Secondary radiation-induced malignancies include thyroid cancer and a variety of sarcomas that may manifest several years after treatment. Checkpoint inhibitors can cause a variety of adverse immune events, including autoimmune hypophysitis and encephalitis.

Reduction of GTV to high-risk CTV radiation margin in head and neck squamous cell carcinoma significantly reduced acute and late radiation-related toxicity with comparable outcomes

BACKGROUND AND PURPOSE

We aim to retrospectively investigate whether reducing GTV to high-risk CTV margin will significantly reduce acute and late toxicity without jeopardizing outcome in head-and-neck squamous cell carcinoma (HNSCC) treated with definitive (chemo)radiation.

MATERIALS AND METHODS

Between April 2015 and April 2019, 155 consecutive patients were treated with GTV to high-risk CTV margin of 10 mm and subsequently another 155 patients with 6 mm margin. The CTV-PTV margin was 3 mm for both groups. All patients were treated with volumetric-modulated arc therapy with daily image-guidance using cone-beam CT. End points of the study were acute and late toxicity and oncologic outcomes.

RESULTS

Overall acute grade 3 toxicity was significantly lower in 6 mm, compared to 10 mm group (48% vs. 67%, respectively, p < 0.01). The same was true for acute grade 3 mucositis (18% vs. 34%, p < 0.01) and grade ≥ 2 dysphagia (67% vs. 85%, p < 0.01). Also feeding tube-dependency at the end of treatment (25% vs. 37%, p = 0.02), at 3 months (12% and 25%, p < 0.01), and at 6 months (6% and 15%, p = 0.01) was significantly less in 6 mm group. The incidence of late grade 2 xerostomia was also significantly lower in the 6 mm group (32% vs. 50%, p < 0.01). The 2-year rates of loco-regional control, disease-free and overall survival were 78.7% vs. 73.1%, 70.6% vs. 61.4%, and 83.2% vs. 74.4% (p > 0.05, all).

CONCLUSION

The first study reporting on reduction of GTV to high-risk CTV margin from 10 to 6 mm showed significant reduction of the incidence and severity of radiation-related toxicity without reducing local-regional control and survival.

Intensity-modulated radiation therapy (IMRT)-based concurrent chemoradiotherapy (CCRT) with Endostar in patients with pelvic locoregional recurrence of cervical cancer: Results from a hospital in the Qinghai-Tibet Plateau

The treatment of recurrent cervical cancer, especially pelvic locoregional recurrence, is very challenging for gynecologic oncologists. This study investigated the efficacy and safety of intensity-modulated radiation therapy (IMRT)-based concurrent chemoradiotherapy (CCRT) with Endostar, a novel modified recombinant human endostatin, in patients with pelvic locoregional recurrence of cervical cancer following surgical treatment.This phase 2 study was conducted between May 2018 and May 2019 at a single center in the Qinghai-Tibet Plateau and enrolled 31 patients with pelvic locoregional recurrence of cervical cancer following surgical treatment. All patients were treated with IMRT-based CCRT for 6 weeks and intravenous infusions of Endostar (15 mg/m), which were administered on days 1 to 7 of CCRT, followed by rest for 4 weeks. After resting, chemotherapy with cisplatin (70 mg/m) plus paclitaxel (135-175 mg/m) was given every 3 weeks for a total of 4 treatments.Thirty-one patients were evaluable for the primary endpoint. The mean age was 50.03 years (SD 7.72). The objective response rate was 67.74% and the disease control rate was 83.87% (48.39% achieved a complete response, 19.35% a partial response, 16.13% had disease stabilization, and 16.13% had progressive disease). The most common adverse events were nausea, vomiting, alopecia, neutropenia, and leukopenia; most events were grade 1 or 2 in intensity. Grade 3 toxicities included thrombocytopenia and neutropenia in 2 patients each, and leukopenia in 4 patients. No cases of grade 4 acute toxicity were observed.IMRT-based CCRT with Endostar infusions is effective and safe. Our results support the use of this treatment for patients with pelvic locoregional recurrence of cervical cancer following surgical treatment.

Head and neck IMPT probabilistic dose accumulation: Feasibility of a 2 mm setup uncertainty setting

OBJECTIVE

To establish optimal robust optimization uncertainty settings for clinical head and neck cancer (HNC) patients undergoing 3D image-guided pencil beam scanning (PBS) proton therapy.

METHODS

We analyzed ten consecutive HNC patients treated with 70 and 54.25 Gy_RBE to the primary and prophylactic clinical target volumes (CTV) respectively using intensity-modulated proton therapy (IMPT). Clinical plans were generated using robust optimization with 5 mm/3% setup/range uncertainties (RayStation v6.1). Additional plans were created for 4, 3, 2 and 1 mm setup and 3% range uncertainty and for 3 mm setup and 3%, 2% and 1% range uncertainty. Systematic and random error distributions were determined for setup and range uncertainties based on our quality assurance program. From these, 25 treatment scenarios were sampled for each plan, each consisting of a systematic setup and range error and daily random setup errors. Fraction doses were calculated on the weekly verification CT closest to the date of treatment as this was considered representative of the daily patient anatomy.

RESULTS

Plans with a 2 mm/3% setup/range uncertainty setting adequately covered the primary and prophylactic CTV (V₉₅ ≥ 99% in 98.8% and 90.8% of the treatment scenarios respectively). The average organ-at-risk dose decreased with 1.1 Gy_RBE/mm setup uncertainty reduction and 0.5 Gy_RBE/1% range uncertainty reduction. Normal tissue complication probabilities decreased by 2.0%/mm setup uncertainty reduction and by 0.9%/1% range uncertainty reduction.

CONCLUSION

The results of this study indicate that margin reduction below 3 mm/3% is possible but requires a larger cohort to substantiate clinical introduction.

Imaging for Target Delineation in Head and Neck Cancer Radiotherapy

The definition of tumor involved volumes in patients with head and neck cancer poses great challenges with the increasing use of highly conformal radiotherapy techniques eg, volumetric modulated arc therapy and intensity modulated proton therapy. The risk of underdosing the tumor might increase unless great care is taken in the process. The information gained from imaging is increasing with both PET and MRI becoming readily available for the definition of targets. The information gained from these techniques is indeed multidimensional as one often acquire data on eg, metabolism, diffusion, and hypoxia together with anatomical and structural information. Nevertheless, much work remains to fully exploit the available information on a patient-specific level. Multimodality target definition in radiotherapy is a chain of processes that must be individually scrutinized, optimized and quality assured. Any uncertainties or errors in image acquisition, reconstruction, interpretation, and delineation are systematic errors and hence will potentially have a detrimental effect on the entire radiotherapy treatment and hence; the chance of cure or the risk of unnecessary side effects. Common guidelines and procedures create a common minimum standard and ground for evaluation and development. In Denmark, the treatment of head and neck cancer is organized within the multidisciplinary Danish Head and Neck Cancer Group (DAHANCA). The radiotherapy quality assurance group of DAHANCA organized a workshop in January 2020 with participants from oncology, radiology, and nuclear medicine from all centers in Denmark, treating patients with head and neck cancer. The participants agreed on a national guideline on imaging for target delineation in head and neck cancer radiotherapy, which has been approved by the DAHANCA group. The guidelines are available in the Supplementary. The use of multimodality imaging is being recommended for the planning of all radical treatments with a macroscopic tumor. 2-[¹⁸F]FDG-PET/CT should be available, preferable in the treatment position. The recommended MRI sequences are T1, T2 with and without fat suppression, and T1 with contrast enhancement, preferable in the treatment position. The interpretation of clinical information, including thorough physical examination as well as imaging, should be done in a multidisciplinary setting with an oncologist, radiologist, and nuclear medicine specialist.

Influence of FAZA PET hypoxia and HPV-status for the outcome of head and neck squamous cell carcinoma (HNSCC) treated with radiotherapy: Long-term results from the DAHANCA 24 trial (NCT01017224)

PURPOSE

Hypoxic tumor volumes can be visualized with ¹⁸F-FAZA PET/CT. In head and neck squamous cell carcinoma (HNSCC), hypoxia is important for the clinical outcome after primary radiotherapy (RT). The outcome is furthermore heavily influenced by the HPV/p16-positivity of oropharyngeal tumors (OPCp16+ tumors). The study purposes were (1) to report on locoregional failures within five years after primary RT in a prospective cohort stratified by both HPV/p16-status and PET hypoxia and (2) to characterize the failure site and the spatial association to PET hypoxia.

MATERIAL AND METHODS

From 2009 to 2011, 38 patients with non-metastatic SCC of the larynx, oro-, hypo- and nasopharynx completing primary RT were included in the prospective DAHANCA 24 trial (NCT01017224). Fifteen patients had OPCp16+ tumors. All were imaged with a static FAZA PET/CT prior to treatment. The hypoxia threshold was determined by a tumor-to-muscle ratio (TMR) of 1.6. Recurrences were documented histologically. Imaging of the recurrence was deformable fused with the pre-treatment FAZA PET/CT. The spatial information of recurrence- and hypoxic volumes were compared visually.

RESULTS

Sixteen patients had more hypoxic tumors (high tracer uptake, TMR ≥1.6) before treatment (42%). With a median follow-up of 7.8 years, nine locoregional recurrences were observed, of which seven were in patients with high-uptake tumors (44% and 9%, respectively, HR 5.8 [1.2-28.2]). The risk of locoregional recurrence was highest among patients with more hypoxic, non-OPCp16+ tumors (57% [21-94%]), with a risk difference of 45% [4-86%], when comparing to less hypoxic, non-OPCp16+ tumors. Eight patients had sufficient imaging of the recurrence for co-registration with the FAZA PET/CT. Six had hypoxic primary tumors, and in two, the recurrence was overlapping the baseline hypoxic subvolume.

CONCLUSION

HNSCC demonstrating a TMR ≥1.6 at baseline is significantly associated with treatment failure after primary RT. In addition to HPV/p16-status, FAZA PET/CT has potential for the selection of tumors requiring treatment intensification.

Definition of locally recurrent head and neck squamous cell carcinoma: a systematic review and proposal for the Odense-Birmingham definition

PURPOSE

The objectives of this study were (1) to systematically review current definitions of head and neck squamous cell carcinoma (HNSCC) recurrence and (2) to propose a definition of locally recurrent HNSCC.

METHODS

A systematic literature review was performed according to the 'Preferred Reporting Items for Systematic Reviews and Meta-Analyses' statement in Medline, Embase, and Cochrane databases guided by the study question "What is the definition of local recurrence for patients with HN:SCC?". All retrieved studies were reviewed and qualitatively analyzed.

RESULTS

The systematic literature search resulted in 3467 publications after removal of duplicates. Forty studies were examined as full text, and a total of five were found suitable for inclusion. All five included studies dealt with definitions of second primary HNSCC and were based on the Warren and Gates Criteria; (1) each of the tumors are malignant, (2) each must be distinct, and (3) the probability of one being a metastasis of the other must be excluded. Each of the included studies added specific anatomical and/or temporal separation measures to the criteria of second primary HNSCC. We propose the definition of locally recurrent HNSCC to be: (1) Same anatomical subsite or adjacent subsite within 3 cm of the primary lesion, (2) time-interval no more than 3 years (from completed treatment of the primary lesion), and (3) same p16-status for oropharyngeal carcinomas.

CONCLUSIONS

No uniform definition of locally recurrent HNSCC currently exists. We propose the Odense-Birmingham definition based on the anatomical subsite combined with a specific measurable distance and a temporal separation of three years.

NTCP model validation method for DAHANCA patient selection of protons versus photons in head and neck cancer radiotherapy

Introduction: Prediction models using logistic regression may perform poorly in external patient cohorts. However, there is a need to standardize and validate models for clinical use. The purpose of this project was to describe a method for validation of external NTCP models used for patient selection in the randomized trial of protons versus photons in head and neck cancer radiotherapy, DAHANCA 35. Material and methods: Organs at risk of 588 patients treated primarily with IMRT in the randomized controlled DAHANCA19 trial were retrospectively contoured according to recent international recommendations. Dose metrics were extracted using MatLab and all clinical parameters were retrieved from the DAHANCA database. The model proposed by Christianen et al. to predict physician-rated dysphagia was validated through the closed testing, where change of the model intercept, slope and individual beta's were tested for significant prediction improvements. Results: Six months prevalence of dysphagia in the validation cohort was 33%. The closed testing procedure for physician-rated dysphagia showed that the Christianen et al. model needed an intercept refitting for the best match for the Danish patients. The intercept update increased the risk of dysphagia for the validation cohort by 7.9 ± 2.5% point. For the raw model performance, the Brier score (mean squared residual) was 0.467, which improved significantly with a new intercept to 0.415. Conclusions: The previously published Dutch dysphagia model needed an intercept update to match the Danish patient cohort. The implementation of a closed testing procedure on the current validation cohort allows quick and efficient validation of external NTCP models for patient selection in the future.

Volumetric and dosimetric comparison of two delineation guidelines for the radiation treatment of laryngeal squamous cell carcinoma

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The delineation of target volumes for Head and Neck IMRT is complex.

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There have been several approaches for the delineation of the primary tumor clinical target volume: the anatomical guidelines, the geometric guidelines and more recently the international guidelines.

Purpose

Three methods have been recently proposed for the delineation of the primary tumor clinical target volume (CTV-P) in Head and Neck Cancers: the anatomic method popularized in the French literature by Lapeyre et al. the geometric methods proposed by the DAHANCA group, and more recently the international guidelines promoted by Grégoire et al. integrating the latter two. The aim of this study was to perform a volumetric and dosimetric comparison of the French and the International consensus methods in laryngeal SCC.

Patients and methods

Two radiation oncologists independently delineated the high dose and low dose primary tumor CTV in four patients with T2 or T3 N0-M0 laryngeal SCC following either the so-called French guidelines or the International guidelines. For the 4 cases, the GTV was delineated by a single radiation oncologist. Nodal CTVs were delineated by one radiation oncologist for the 4 cases using International guidelines. Dose optimization was then performed with VMAT (MONACO version 5.11) using 6 MeV photons. Differences in target volumes and dose distributions in OARs and PTVs were then evaluated with various metrics such as the DICE Similarity Coefficient and the homogeneity index.

Results

Major differences were observed in the CTV delineation between the 2 delineation methods for the low dose volumes and to a lower extend for the high dose volumes. These differences translated into variations in dose distribution favoring the International guidelines for decreasing dose to various OARs. Such differences toned down when dose distribution on the primary tumors PTVs and nodal PTVs were combined.

Conclusion

This study demonstrated large differences in CTV delineation between the 2 delineation guidelines. Such differences translated into differences in dose distribution.

Reducing radiotherapy target volume expansion for patients with HPV-associated oropharyngeal cancer

PURPOSE

To evaluate clinical outcomes and patterns of failure using a direct gross tumor volume to planning target volume expansion in patients with p16-positive oropharyngeal squamous cell carcinoma.

METHODS AND MATERIALS

We performed a retrospective review of patients with p16-positive oropharyngeal squamous cell carcinomas treated between 2002 and 2017 with primary radiotherapy with or without concurrent systemic therapy. Patient and disease characteristics associated with disease control and clinical outcomes were analyzed by Cox proportional hazards regression and Kaplan-Meier analyses. Imaging at the time of first failure was used to categorize failure patterns.

RESULTS

We identified 134 patients with a median follow-up of 56.2 months (range 8.2-160.2 months). Local and regional control at 5 years was 91.5% (95% CI: 86.8-96.4%), and 90.8% (95% CI: 85.6-96.2%), respectively. Of the 14 locoregional failures, there were 10 in-field (Type A), 3 marginal (Type B), and 1 geographic (Type E). Age >70 years (HR 5.42; 95% CI: 1.87-15.68) and T4 versus T1-3 (HR 4.09; 95% CI: 1.01-2.65) were associated with increased rates of locoregional failure on multivariate analysis. The rate of gastrostomy tube retention at one year was 6.0% (range 2.8-12.7%).

CONCLUSIONS

Management of patients with p16-positive oropharyngeal squamous cell carcinoma using definitive radiotherapy and a high-dose planning target volume created without a gross tumor volume to clinical tumor volume expansion resulted in high locoregional control with the vast majority of failures occurring within the high-dose field. These data warrant prospective evaluation of this technique as a therapy de-intensification approach.

Intensity-modulated radiation therapy for definitive treatment of cervical cancer: a meta-analysis

Background

To compare the efficacies and toxicities of intensity-modulated radiotherapy (IMRT) with three-dimensional conformal radiotherapy (3D-CRT) or conventional two-dimensional radiotherapy (2D-RT) for definitive treatment of cervical cancer.

Methods

A meta-analysis was performed using search engines, including PubMed, Cochrane Library, Web of Science, and Elsevier. In the meta-analysis, odds ratios (ORs) were compared for overall survival (OS), disease-free survival (DFS), and acute and chronic toxicities.

Results

Included data were analysed using RevMan 5.2 software. Six studies encompassing a total of 1008 patients who received definitive treatment (IMRT = 350, 3-DCRT/2D-RT = 658) were included in the analysis. A comparison of 3-year OS and 3-year DFS revealed no significant differences between IMRT and 3D-CRT or 2D-RT (3-year OS: OR = 2.41, 95% confidence interval [CI]: 0.62–9.39, p = 0.21; 3-year DFS: OR = 1.44, 95% CI: 0.69–3.01, p = 0.33). The incidence of acute gastrointestinal (GI) toxicity and genitourinary (GU) toxicity in patients who received IMRT was significantly lower than that in the control group (GI: Grade 2: OR = 0.5, 95% CI: 0.28–0.89, p = 0.02; Grade 3 or higher: OR = 0.55, 95% CI: 0.32–0.95, p = 0.03; GU: Grade 2: OR = 0.41, 95% CI: 0.2–0.84; p = 0.01; Grade 3 or higher: OR = 0.31, 95% CI: 0.14–0.67, p = 0.003). Moreover, the IMRT patients experienced fewer incidences of chronic GU toxicity than did the control group (Grade 3: OR = 0.09, 95% CI: 0.01–0.67, p = 0.02).

Conclusion

IMRT and conventional radiotherapy demonstrated equivalent efficacy in terms of 3-year OS and DFS. Additionally, IMRT significantly reduced acute GI and GU toxicities as well as chronic GU toxicity in patients with cervical cancer.

Practical clinical guidelines for contouring the trigeminal nerve (V) and its branches in head and neck cancers

PURPOSE

The trigeminal nerve (V) is a major route of tumor spread in several head and neck cancers. However, only limited data are currently available for its precise contouring, although this is absolutely necessary in the era of intensity-modulated radiation therapy (IMRT). The purpose of this article is to present practical clinical guidelines for contouring the trigeminal nerve (V) in head and neck cancers at risk of spread along this nerve.

METHOD

The main types of head and neck cancers associated with risks of spread along the trigeminal nerve (V) and its branches were comprehensively reviewed based on clinical experience, literature-based patterns of failure, anatomy and radio-anatomy. A consensus for contouring was proposed based on a multidisciplinary approach among head and neck oncology experts including radiation oncologists (JBi, ML, MO, VG and JB), a radiologist (VD) and a surgeon (CS). These practical clinical guidelines have been endorsed by the GORTEC (Head and Neck Radiation Oncology Group).

RESULTS

We provided contouring and treatment guidelines, supported by detailed figures and tables to help, for the trigeminal nerve and its branches: the ophthalmic nerve (V1), the maxillary nerve (V2) and the manidibular nerve (V3). A CT- and MRI-based atlas was proposed to illustrate the whole trigeminal nerve pathway with its main branches.

CONCLUSION

Trigeminal nerve (V) invasion is an important component of the natural history of various head and neck cancers. Recognizing the radio-anatomy and potential routes of invasion is essential for optimal contouring, as presented in these guidelines.

Verification of HE-based CTV in laryngeal and hypopharyngeal cancer using pan-cytokeratin

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Currently clinical CTV margins lack evidence and need (histopathological) validation.

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Tumor outline on HE and pan-cytokeratin staining are comparable for laryngeal cancer.

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HE-based delineations can be used for histopathology based CTV-margin definition.

Background

For accurate target definition, we determined margins for the clinical target volume (CTV) for laryngeal and hypopharyngeal cancer in computed tomography (CT, 4.3 mm), magnetic resonance imaging (MR, 6.1 mm) and fluorodeoxyglucose (FDG)-positron emission tomography (PET, 5.2 mm). Previously, we used Hematoxylin-eosin (HE) stained whole-mount sections of total laryngectomy specimens as gold standard to define CTV margins. In the present study, we verified the HE-based tumor delineation with staining for pan-cytokeratin, specific for squamous cell carcinoma.

Methods

Twenty-seven patients with a T3/T4 laryngeal hypopharyngeal tumor were included. From each patient, a total laryngectomy specimen was obtained. Four subsequent 3-mm thick slices containing tumor were selected of which 4-µm thick whole-mount sections were obtained and stained with HE and for pan-cytokeratin CK-AE1/3. Tumors were microscopically delineated on both sections by an experienced head-and-neck pathologist. Tumor delineations were compared using the conformity index (CI) and the distance between both contours.

Results

The CI between HE-based and CK-AE1/3-based tumor delineations was 0.87. The maximum and 95th percentile (p95) extent of the HE-based tumor delineations from the CK-AE1/3-based tumor delineations were 1.7 mm and 0.7 mm, respectively. The maximum and p95 extent of the CK-AE1/3-based tumor delineations from the HE-based tumor delineations was 1.9 mm and 0.8 mm, respectively.

Conclusions

Histopathological assessment of tumor outline on standard HE-stained sections is comparable to microscopic tumor extent based on squamous cell specific pan-cytokeratin staining. Therefore, CTV margins based on HE based tumor contour will be adequate.

The impact of margin reduction on outcome and toxicity in head and neck cancer patients treated with image-guided volumetric modulated arc therapy (VMAT)

BACKGROUND AND PURPOSE

In recent decades, outcomes of patients with head and neck cancer (HNC) have improved as a result of implementing several strategies, such as chemoradiation. However, these improvements were achieved at the cost of increased toxicity. One way to reduce radiation-related toxicity is by reducing the margins.

MATERIALS AND METHODS

Between 2013 and 2016, 206 consecutive patients were treated with CTV-PTV margin of 5 mm and subsequently 208 patients with 3 mm margin. This study evaluates the impact of reducing clinical target volume (CTV) to planning target volume (PTV) margin on outcome and toxicity.

RESULTS

All patients were treated with volumetric modulated arc therapy (VMAT) with daily-image guidance using cone-beam CT (CBCT). Overall acute grade 3 toxicity was significantly lower in 3 mm-group, compared to 5 mm-group (53.8% vs. 65%, respectively, p = 0.032). The same was true for acute grade 3 mucositis (30.8% vs. 42.2%, p = 0.008) and for acute grade 3 dysphagia (feeding tube-dependence) (22.1% vs. 33.5%, p = 0.026). The incidence of ongoing feeding tube-dependence after 3 months of radiotherapy was 11.1% and 20.4%, respectively (p = 0.012). The 2-year incidence of late grade ≥2 xerostomia was 15.8% and 19.4% (p = 0.8). The 2-year loco-regional control rates of patients treated in 3 mm and 5 mm-groups were 79.9% and 79.2% (p = 1.0). The figures for disease-free survival were 71.5% and 72.7 (p = 0.6) and for overall survival were 75.2% and 75.1% (p = 0.9).

CONCLUSION

Reducing the CTV-PTV margin from 5 to 3 mm combined with daily CBCT-guided VMAT reduced the severity, frequency, and duration of radiation-related toxicity without jeopardizing outcome.