Outcomes of Tolerability, Acute Toxicity and Quality of Life from MR-Guided Radiation Therapy (1.5T MR-Linac) for Liver Metastases in the MOMENTUM Study

PURPOSE/OBJECTIVE(S)

Stereotactic body radiation therapy (SBRT) offers an important treatment option for metastatic liver tumors. The introduction of magnetic resonance (MR) guided SBRT has paved the way for optimal tumor visualization and daily plan adaptation. The purpose of this study is to review tolerability of MR-guided SBRT of liver metastases and to present early toxicity and quality of life outcomes.

MATERIALS/METHODS

All patients with liver metastases who were treated on a 1.5T MR-Linac and enrolled in the MOMENTUM study (NTC04075305) were included. Patients were treated between April 2019 and December 2022 in 5 different institutes across 3 countries. Descriptive statistics were used to present the tolerability of treatment, toxicity (CTCAE v5.0) and quality of life outcomes (QLQ C30 and EQ 5D-5L) at baseline and 3 months after treatment.

RESULTS

A total of 127 patients with liver metastases were included in the analysis. There were 64 females and 63 men, with a median age of 66 years (range 31 to 93). The median ECOG-score was 0 (range 0-2). The most common primary origin was colorectal cancer (66%), followed by bronchus and lung cancer (12%), with ocular melanoma, pancreatic and breast cancer being joint third (all 6-7%). Fractionation schedules ranged from 12 - 67.5 Gy in 2 - 12 fractions. The most commonly prescribed fractionation dose was 60 Gy in 3-5 fractions (53% and 13% respectively) and 50 Gy in 5 fractions (11%). Completion data was available for 116 patients. 112 patients (97%) received all fractions. 4 Patients (3%) did not complete treatment due to technical issues and 2 of the 4 receiving no treatment on the MR-Linac. Physician reported toxicity at 3 months was recorded for 82 patients (66%). No grade 4 or 5 toxicities were reported. There were 12 grade 3 toxicities reported in 6 (7%) patients with 5 deemed radiation therapy related (Table 1) and 34 grade 2 toxicities in 21 (26%) patients.

CONCLUSION

We have presented the largest cohort (to our knowledge) of 127 patients treated using 1.5 Tesla MR Guidance for metastatic liver tumors. 97% of treatments were completed successfully with all treatments being well tolerated. Acute grade 3 toxicity was reported in 7% of patients with no grade 4 or 5 toxicities present. These outcomes suggest radiotherapy on the MR-Linac is a safe and promising treatment for patients with liver metastases. Additional prospective follow up is ongoing for late toxicity events and long-term control data. Table 1: Grade ≥3 toxicity at 3 months related to radiation therapy (total No. of patients was 82) There was QLQ-C30 data on 89 patients at baseline and on 62 patients at 3 months. At 3 months the median score was worse for physical functioning, VAS score and pain.

Differential Response in Quantitative MRI Parameters Detected in Head and Neck Cancer Patients Treated with Concurrent Immunotherapy during Hypo-Fractionated MR-gRT

PURPOSE/OBJECTIVE(S)

Recently, multiple clinical trials have demonstrated success of PD-1/PD-L1-targeted immune checkpoint inhibition (ICI) in recurrent and metastatic head and neck cancer (HNC). However, three large clinical trials combining PD-1/PD-L1-targeted ICI with RT or chemo-RT (CRT) in the definitive management of HNC have shown no benefit of combination therapy with ICI over RT or CRT alone. Our overarching hypotheses are: i) hypo-fractionation may ultimately better synergize with ICI compared to conventional RT regimens, and ii) immunologic changes in the tumor microenvironment may be detectable using quantitative MRI (qMRI) parameters collected during RT.

MATERIALS/METHODS

Seven patients treated with hypo-fractionated MR-guided RT of 50 Gy in 15 fractions (DEHART, NCT04477759) were included in the study. Four patients (Group 1) were treated with concurrent atezolizumab (a monoclonal antibody) and three patients (Group 2) were treated with RT alone. Daily DWI, T1 mapping, and T2 mapping sequences were acquired on a 1.5T MR-Linac in the idle time during adaptive plan generation. Median ADC, T1, T2, and Dslow (derived from b-values 150 and 550 s/mm2) values were extracted from physician-defined GTV and manually constructed posterior paraspinal muscle contours, the latter serving as a control. Wilcoxon signed rank tests were conducted using pre/post treatment data for each qMRI parameter.

RESULTS

GTV ADC, Dslow, T2, and T1 increased for both patient groups over the course of treatment with significant differences in ADC, Dslow, and T2 detected between fractions 1 and 15 for all patients studied (p = 0.0156, p = 0.0156, and p = 0.0469, respectively). No significant differences were detected in control qMRI parameters pre/post treatment. No significant differences in ADC, Dslow, and T2 were detected between groups' fractions 1 and 15 in these small cohorts. However, interestingly, we observed a differential change in the increase of median GTV T2 and Dslow values during fractions 10-12 in Group 1 compared to Group 2, suggesting this time interval may prime the anti-tumor immune response.

CONCLUSION

Combining hypo-fractionated RT with ICI leads to a differential response in quantitative MRI (qMRI) parameters in HNC patients. These results suggest that qMRI parameter changes ten days following the start of RT may reflect a critical juncture in the anti-tumoral immune response when ICI is combined with hypo-fractionated RT.

Chronic stress promotes an immunologic inflammatory state and head and neck cancer growth in a humanized murine model

BACKGROUND

Despite the importance of immune response and environmental stress on head and neck cancer (HNC) outcomes, no current pre-clinical stress model includes a humanized immune system.

METHODS

We investigated the effects of chronic stress induced by social isolation on tumor growth and human immune response in subcutaneous HNC tumors grown in NSG-SGM3 mice engrafted with a human immune system.

RESULTS

Tumor growth (p < 0.0001) and lung metastases (p = 0.035) were increased in socially isolated versus control animals. Chronic stress increased intra-tumoral CD4+ T-cell infiltrate (p = 0.005), plasma SDF-1 (p < 0.0001) expression, and led to tumor cell dedifferentiation toward a cancer stem cell phenotype (CD44+ /ALDHhigh , p = 0.025).

CONCLUSIONS

Chronic stress induced immunophenotypic changes, increased tumor growth, and metastasis in HNC in a murine model with a humanized immune system. This model system may provide further insight into the immunologic and oncologic impact of chronic stress on patients with HNC.

A Volume-Independent Conformity Index for Stereotactic Radiosurgery

PURPOSE

To develop a volume-independent conformity metric called the Gaussian Weighted Conformity Index (GWCI) to evaluate stereotactic radiosurgery/radiotherapy (SRS/SRT) plans for small brain tumors.

METHODS

A signed bi-directional local distance (BLD) between the prescription isodose line and the target contour is determined for each point along the tumor contour (positive distance represents under-coverage). A similarity score function is derived from Gaussian function, penalizing under- and over-coverage at each point by assigning standard deviations of the Gaussian function. Each point along the dose line contour is scored with this score function. The average of the similarity scores determines the GWCI. A total of 40 targets from 18 patients who received Gamma-Knife SRS/SRT treatments were analyzed to determine appropriate penalty criteria. The resulting GWCIs for test cases already deemed clinically acceptable are presented and compared to the same cases scored with the New Conformity Index to determine the influence of tumor volumes on the two conformity indices.

RESULTS

A total of four penalty combinations were tested based on the signed BLDs from the 40 targets. A GWCI of 0.9 is proposed as a cutoff for plan acceptability. The GWCI exhibits no target volume dependency as designed.

CONCLUSION

A limitation of current conformity indices, volume dependency, becomes apparent when applied to SRS/SRT plans. The GWCI appears to be a more robust index which penalizes over- and under-coverage of tumors and is not skewed by the tumor volume. This article is protected by copyright. All rights reserved.

General and custom deep learning autosegmentation models for organs in head and neck, abdomen, and male pelvis

PURPOSE

To reduce workload and inconsistencies in organ segmentation for radiation treatment planning, we developed and evaluated general and custom autosegmentation models on computed tomography (CT) for three major tumor sites using a well-established deep convolutional neural network (DCNN).

METHODS

Five CT-based autosegmentation models for 42 organs at risk (OARs) in head and neck (HN), abdomen (ABD), and male pelvis (MP) were developed using a full three-dimensional (3D) DCNN architecture. Two types of deep learning (DL) models were separately trained using either general diversified multi-institutional datasets or custom well-controlled single-institution datasets. To improve segmentation accuracy, an adaptive spatial resolution approach for small and/or narrow OARs and a pseudo scan extension approach, when CT scan length is too short to cover entire organs, were implemented. The performance of the obtained models was evaluated based on accuracy and clinical applicability of the autosegmented contours using qualitative visual inspection and quantitative calculation of dice similarity coefficient (DSC), mean distance to agreement (MDA), and time efficiency.

RESULTS

The five DL autosegmentation models developed for the three anatomical sites were found to have high accuracy (DSC ranging from 0.8 to 0.98) for 74% OARs and marginally acceptable for 26% OARs. The custom models performed slightly better than the general models, even with smaller custom datasets used for the custom model training. The organ-based approaches improved autosegmentation accuracy for small or complex organs (e.g., eye lens, optic nerves, inner ears, and bowels). Compared with traditional manual contouring times, the autosegmentation times, including subsequent manual editing, if necessary, were substantially reduced by 88% for MP, 80% for HN, and 65% for ABD models.

CONCLUSIONS

The obtained autosegmentation models, incorporating organ-based approaches, were found to be effective and accurate for most OARs in the male pelvis, head and neck, and abdomen. We have demonstrated that our multianatomical DL autosegmentation models are clinically useful for radiation treatment planning.

Tumor Control Probability Modeling for Radiation Therapy of Keratinocyte Carcinoma

Summary

Skin cancer patients may be treated definitively using radiation therapy (RT) with electrons, kilovoltage, or megavoltage photons depending on tumor stage and invasiveness. This study modeled tumor control probability (TCP) based on the pooled clinical outcome data of RT for primary basal and cutaneous squamous cell carcinomas (BCC and cSCC, respectively). Four TCP models were developed and found to be potentially useful in developing optimal treatment schemes based on recommended ASTRO 2020 Skin Consensus Guidelines for primary, keratinocyte carcinomas (i.e. BCC and cSCC).

Background

Radiotherapy (RT) with electrons or photon beams is an excellent primary treatment option for keratinocyte carcinoma (KC), particularly for non-surgical candidates. Our objective is to model tumor control probability (TCP) based on the pooled clinical data of primary basal and cutaneous squamous cell carcinomas (BCC and cSCC, respectively) in order to optimize treatment schemes.

Methods

Published reports citing crude estimates of tumor control for primary KCs of the head by tumor size (diameter: ≤2 cm and >2 cm) were considered in our study. A TCP model based on a sigmoidal function of biological effective dose (BED) was proposed. Three-parameter TCP models were generated for BCCs ≤2 cm, BCCs >2cm, cSCCs ≤2 cm, and cSCCs >2 cm. Equivalent fractionation schemes were estimated based on the TCP model and appropriate parameters.

Results

TCP model parameters for both BCC and cSCC for tumor sizes ≤2 cm and >2cm were obtained. For BCC, the model parameters were found to be TD₅₀ = 56.62 ± 6.18 × 10^-3 Gy, k = 0.14 ± 2.31 × 10⁻² Gy⁻¹ and L = 0.97 ± 4.99 × 10⁻³ and TD₅₀ = 55.78 ± 0.19 Gy, k = 1.53 ± 0.20 Gy⁻¹ and L = 0.94 ± 3.72 × 10⁻³ for tumor sizes of ≤2 cm and >2 cm, respectively. For SCC the model parameters were found to be TD₅₀ = 56.81 ± 19.40 × 10⁴ Gy, k = 0.13 ± 7.92 × 10⁴ Gy⁻¹ and L = 0.96 ± 1.31 × 10^-2 and TD₅₀ = 58.44 ± 0.30 Gy, k = 2.30 ± 0.43 Gy⁻¹ and L = 0.91± 1.22 × 10⁻² for tumors ≤2cm and >2 cm, respectively. The TCP model with the derived parameters predicts that radiation regimens with higher doses, such as increasing the number of fractions and/or dose per fraction, lead to higher TCP, especially for KCs >2 cm in size.

Conclusion

Four TCP models for primary KCs were developed based on pooled clinical data that may be used to further test the recommended kV and MV x-ray and electron RT regimens from the 2020 ASTRO guidelines. Increasing both number of fractions and dose per fraction may have clinically significant effects on tumor control for tumors >2 cm in size for both BCC and cSCC.

Initial Feasibility and Clinical Implementation of Daily MR-Guided Adaptive Head and Neck Cancer Radiation Therapy on a 1.5T MR-Linac System: Prospective R-IDEAL 2a/2b Systematic Clinical Evaluation of Technical Innovation

PURPOSE

This prospective study is, to our knowledge, the first report of daily adaptive radiation therapy (ART) for head and neck cancer (HNC) using a 1.5T magnetic resonance imaging-linear accelerator (MR-linac) with particular focus on safety and feasibility and dosimetric results of an online rigid registration-based adapt to position (ATP) workflow.

METHODS AND MATERIALS

Ten patients with HNC received daily ART on a 1.5T/7MV MR-linac, 6 using ATP only and 4 using ATP with 1 offline adapt-to-shape replan. Setup variability with custom immobilization masks was assessed by calculating the mean systematic error (M), standard deviation of the systematic error (Σ), and standard deviation of the random error (σ) of the isocenter shifts. Quality assurance was performed with a cylindrical diode array using 3%/3 mm γ criteria. Adaptive treatment plans were summed for each patient to compare the delivered dose with the planned dose from the reference plan. The impact of dosimetric variability between adaptive fractions on the summation plan doses was assessed by tracking the number of optimization constraint violations at each individual fraction.

RESULTS

The random errors (mm) for the x, y, and z isocenter shifts, respectively, were M = -0.3, 0.7, 0.1; Σ = 3.3, 2.6, 1.4; and σ = 1.7, 2.9, 1.0. The median (range) γ pass rate was 99.9% (90.9%-100%). The differences between the reference and summation plan doses were -0.61% to 1.78% for the clinical target volume and -11.74% to 8.11% for organs at risk (OARs), although an increase greater than 2% in OAR dose only occurred in 3 cases, each for a single OAR. All cases had at least 2 fractions with 1 or more constraint violations. However, in nearly all instances, constraints were still met in the summation plan despite multiple single-fraction violations.

CONCLUSIONS

Daily ART on a 1.5T MR-linac using an online ATP workflow is safe and clinically feasible for HNC and results in delivered doses consistent with planned doses.

Risk groups of laryngeal cancer treated with chemoradiation according to nomogram scores - A pooled analysis of RTOG 0129 and 0522

OBJECTIVES

To develop nomograms predicting overall survival (OS), freedom from locoregional recurrence (FFLR), and freedom from distant metastasis (FFDM) for patients receiving chemoradiation for laryngeal squamous cell carcinoma (LSCC).

MATERIAL AND METHODS

Clinical and treatment data for patients with LSCC enrolled on NRG Oncology/RTOG 0129 and 0522 were extracted from the RTOG database. The dataset was partitioned into 70% training and 30% independent validation datasets. Significant predictors of OS, FFLR, and FFDM were obtained using univariate analysis on the training dataset. Nomograms were built using multivariate analysis with four a priori variables (age, gender, T-stage, and N-stage) and significant predictors from the univariate analyses. These nomograms were internally and externally validated using c-statistics (c) on the training and validation datasets, respectively.

RESULTS

The OS nomogram included age, gender, T stage, N stage, and number of cisplatin cycles. The FFLR nomogram included age, gender, T-stage, N-stage, and time-equivalent biologically effective dose. The FFDM nomogram included age, gender, N-stage, and number of cisplatin cycles. Internal validation of the OS nomogram, FFLR nomogram, and FFDM nomogram yielded c = 0.66, c = 0.66 and c = 0.73, respectively. External validation of these nomograms yielded c = 0.59, c = 0.70, and c = 0.73, respectively. Using nomogram score cutoffs, three risk groups were separated for each outcome.

CONCLUSIONS

We have developed and validated easy-to-use nomograms for LSCC outcomes using prospective cooperative group trial data.

Data from a terminated study on iron oxide nanoparticle magnetic resonance imaging for head and neck tumors

Node positive head and neck squamous cell carcinomas (HNSCCs) patients exhibit worse outcomes in terms of regional neck control, risk for distant metastases and overall survival. Smaller non-palpable lymph nodes may be inflammatory or may harbor clinically occult metastases, a characterization that can be challenging to make using routine imaging modalities. Ferumoxytol has been previously investigated as an intra-tumoral contrast agent for magnetic resonance imaging (MRI) for intracranial malignancies and lymph node agent in prostate cancer. Hence, our group was motivated to carry out a prospective feasibility study to assess the feasibility of ferumoxytol dynamic contrast enhanced (DCE)-weighted MRI relative to that of gadolinium-based DCE-MRI for nodal and primary tumor imaging in patients with biopsy-proven node-positive HNSCC or melanoma. Although this institutional review board (IRB)-approved study was prematurely terminated because of an FDA black box warning, the investigators sought to curate and publish this unique dataset of matched clinical, and anatomical and DCE MRI data for the enrolled five patients to be available for scientists interested in molecular imaging.

Measurement(s)	imaging assay • head and neck squamous cell carcinoma
Technology Type(s)	magnetic resonance imaging
Factor Type(s)	contrast agent
Sample Characteristic - Organism	Homo sapiens

Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.11409516

Final results of a multi-institutional phase II trial of reirradiation with concurrent weekly cisplatin and cetuximab for recurrent or second primary squamous cell carcinoma of the head and neck

Background

The optimal regimen of chemotherapy and reirradiation (re-XRT) for recurrent head and neck squamous cell carcinoma (HNSCC) is controversial. We report the final outcomes of a multicenter phase II trial evaluating cetuximab and cisplatin-based chemotherapy concurrent with re-XRT for patients with recurrent HNSCC.

Materials and methods

Patients with unresectable recurrent disease or positive margins after salvage surgery arising within a previously irradiated field with KPS ≥ 70 were eligible for this trial. Cetuximab 400 mg/m2 was delivered as a loading dose in week 1 followed by weekly cetuximab 250 mg/m2 and cisplatin 30 mg/m2 concurrent with 6 weeks of intensity-modulated radiotherapy to a dose of 60-66 Gy in 30 daily fractions. Patients who previously received both concurrent cetuximab and cisplatin with radiation or who received radiotherapy less than 6 months prior were ineligible.

Results

From 2009 to 2013, 48 patients enrolled on this trial, 2 did not receive any protocol treatment. Of the remaining 46 patients, 34 were male and 12 female, with a median age of 62 years (range 36-85). Treatment was feasible and only 1 patient did not complete the treatment course. Common grade 3 or higher acute toxicities were lymphopenia (46%), pain (22%), dysphagia (13%), radiation dermatitis (13%), mucositis (11%) and anorexia (11%). There were no grade 5 acute toxicities. Eight grade 3 late toxicities were observed, four of which were swallowing related. With a median follow-up of 1.38 years, the 1-year overall survival (OS) was 60.4% and 1-year recurrence-free survival was 34.1%. On univariate analysis, OS was significantly improved with young age (P = 0.01). OS was not associated with radiation dose, surgery before re-XRT or interval from prior XRT.

Conclusions

Concurrent cisplatin and cetuximab with re-XRT is feasible and offers good treatment outcomes for patients with high-risk features. Younger patients had significantly improved OS.

ClinicalTrials.Gov Identifier

NCT00833261.

Post-radiotherapy PET/CT for predicting treatment outcomes in head and neck cancer after postoperative radiotherapy

PURPOSE

The purpose of this study was to retrospectively review the role of post-treatment (post-tx) FDG-PET/CT scans in patients receiving postoperative intensity-modulated radiotherapy (IMRT) for head and neck squamous cell carcinomas (HNSCC).

MATERIALS AND METHODS

Eighty-two patients with HNSCC treated with surgery and postoperative IMRT with or without chemotherapy from October 15, 2008 to December 31, 2014 that had post-tx PET/CT within 6 months of completing IMRT were included. PET/CT was considered positive based on multi-disciplinary review integrating clinical information. Survival analysis was performed using the Kaplan-Meier method. Categorical and continuous predictors of positive post-tx PET/CT were evaluated using Fisher's exact test and logistic regression, respectively. Predictors for survival outcomes were evaluated with log-rank testing. A p ≤ 0.05 was considered statistically significant.

RESULTS

Median follow-up was 3.88 years. For all patients, 3-year overall survival (OS) and recurrence-free survival (RFS) were 71.8% and 61.3%, respectively. Patients with positive post-tx PET/CT had worse OS compared to those with negative post-tx PET/CT (log rank p < 0.001). For patients with positive post-tx PET/CT, 3-year OS was 11.2% compared to 89.9% for patients with negative post-tx PET/CT. The positive predictive value (PPV) of PET/CT was 100% for local recurrence (LR), regional recurrence (RR) and distant metastasis (DM). The negative predictive values (NPV) for LR, RR and DM were 89.0%, 89.2%, and 85.9%, respectively. Perineural invasion (p = 0.009), p16 status (p = 0.009), non-oropharyngeal primary site (p = 0.002), and the use of chemotherapy (p = 0.01) were independent predictors of positive PET/CT.

CONCLUSIONS

Post-tx PET/CT after postoperative radiation is prognostic for survival outcomes. The PPV of post-tx PET for recurrence was excellent, allowing for early detection of recurrent disease. Post-tx PET/CT should be considered after postoperative radiation.

A prospective in silico analysis of interdisciplinary and interobserver spatial variability in post-operative target delineation of high-risk oral cavity cancers: Does physician specialty matter?

Background

The aim of this study was to determine the interdisciplinary agreement in identifying the post-operative tumor bed.

Methods

Three radiation oncologists (ROs), four surgeons, and three radiologists segmented post-operative tumor and nodal beds for three patients with oral cavity cancer. Specialty cohort composite contours were created by STAPLE algorithm implementation results for interspecialty comparison. Dice similarity coefficient and Hausdorff distance were utilized to compare spatial differentials between specialties.

Results

There were significant differences between disciplines in target delineation. There was unacceptable variation in Dice similarity coefficient for each observer and discipline when compared to the STAPLE contours. Within surgery and radiology disciplines, there was good consistency in volumes. ROs and radiologists have similar Dice similarity coefficient scores compared to surgeons.

Conclusion

There were significant interdisciplinary differences in perceptions of tissue-at-risk. Better communication and explicit description of at-risk areas between disciplines is required to ensure high-risk areas are adequately targeted.

A Multi-institutional Comparison of SBRT and IMRT for Definitive Reirradiation of Recurrent or Second Primary Head and Neck Cancer

PURPOSE

Two modern methods of reirradiation, intensity modulated radiation therapy (IMRT) and stereotactic body radiation therapy (SBRT), are established for patients with recurrent or second primary squamous cell carcinoma of the head and neck (rSCCHN). We performed a retrospective multi-institutional analysis to compare methods.

METHODS AND MATERIALS

Data from patients with unresectable rSCCHN previously irradiated to ≥40 Gy who underwent reirradiation with IMRT or SBRT were collected from 8 institutions. First, the prognostic value of our IMRT-based recursive partitioning analysis (RPA) separating those patients with unresectable tumors with an intertreatment interval >2 years or those with ≤2 years and without feeding tube or tracheostomy dependence (class II) from other patients with unresected tumors (class III) was investigated among SBRT patients. Overall survival (OS) and locoregional failure were then compared between IMRT and SBRT by use of 2 methods to control for baseline differences: Cox regression weighted by the inverse probability of treatment and subset analysis by RPA classification.

RESULTS

The study included 414 patients with unresectable rSCCHN: 217 with IMRT and 197 with SBRT. The unadjusted 2-year OS rate was 35.4% for IMRT and 16.3% for SBRT (P<.01). Among SBRT patients, RPA classification retained an independent association with OS. On Cox regression weighted by the inverse probability of treatment, no significant differences in OS or locoregional failure between IMRT and SBRT were demonstrated. Analysis by RPA class showed similar OS between IMRT and SBRT for class III patients. In all class II patients, IMRT was associated with improved OS (P<.001). Further subset analysis demonstrated comparable OS when ≥35 Gy was delivered with SBRT to small tumor volumes. Acute grade ≥4 toxicity was greater in the IMRT group than in the SBRT group (5.1% vs 0.5%, P<.01), with no significant difference in late toxicity.

CONCLUSIONS

Reirradiation both with SBRT and with IMRT appear relatively safe with favorable toxicity compared with historical studies. Outcomes vary by RPA class, which informs clinical trial design. Survival is poor in class III patients, and alternative strategies are needed.

Volume, Dose, and Fractionation Considerations for IMRT-based Reirradiation in Head and Neck Cancer: A Multi-institution Analysis

PURPOSE

Limited data exist to guide the treatment technique for reirradiation of recurrent or second primary squamous carcinoma of the head and neck. We performed a multi-institution retrospective cohort study to investigate the effect of the elective treatment volume, dose, and fractionation on outcomes and toxicity.

METHODS AND MATERIALS

Patients with recurrent or second primary squamous carcinoma originating in a previously irradiated field (≥40 Gy) who had undergone reirradiation with intensity modulated radiation therapy (IMRT); (≥40 Gy re-IMRT) were included. The effect of elective nodal treatment, dose, and fractionation on overall survival (OS), locoregional control, and acute and late toxicity were assessed. The Kaplan-Meier and Gray's competing risks methods were used for actuarial endpoints.

RESULTS

From 8 institutions, 505 patients were included in the present updated analysis. The elective neck was not treated in 56.4% of patients. The median dose of re-IMRT was 60 Gy (range 39.6-79.2). Hyperfractionation was used in 20.2%. Systemic therapy was integrated for 77.4% of patients. Elective nodal radiation therapy did not appear to decrease the risk of locoregional failure (LRF) or improve the OS rate. Doses of ≥66 Gy were associated with improvements in both LRF and OS in the definitive re-IMRT setting. However, dose did not obviously affect LRF or OS in the postoperative re-IMRT setting. Hyperfractionation was not associated with improved LRF or OS. The rate of acute grade ≥3 toxicity was 22.1% overall. On multivariable logistic regression, elective neck irradiation was associated with increased acute toxicity in the postoperative setting. The rate of overall late grade ≥3 toxicity was 16.7%, with patients treated postoperatively with hyperfractionation experiencing the highest rates.

CONCLUSIONS

Doses of ≥66 Gy might be associated with improved outcomes in high-performance patients undergoing definitive re-IMRT. Postoperatively, doses of 50 to 66 Gy appear adequate after removal of gross disease. Hyperfractionation and elective neck irradiation were not associated with an obvious benefit and might increase toxicity.

Patterns-of-failure guided biological target volume definition for head and neck cancer patients: FDG-PET and dosimetric analysis of dose escalation candidate subregions

BACKGROUND

To identify the radio-resistant subvolumes in pretreatment FDG-PET by mapping the spatial location of the origin of tumor recurrence after IMRT for head-and-neck squamous cell cancer to the pretreatment FDG-PET/CT.

METHODS

Patients with local/regional recurrence after IMRT with available FDG-PET/CT and post-failure CT were included. For each patient, both pre-therapy PET/CT and recurrence CT were co-registered with the planning CT (pCT). A 4-mm radius was added to the centroid of mapped recurrence growth target volumes (rGTV's) to create recurrence nidus-volumes (NVs). The overlap between boost-tumor-volumes (BTV) representing different SUV thresholds/margins combinations and NVs was measured.

RESULTS

Forty-seven patients were eligible. Forty-two (89.4%) had type A central high dose failure. Twenty-six (48%) of type A rGTVs were at the primary site and 28 (52%) were at the nodal site. The mean dose of type A rGTVs was 71Gy. BTV consisting of 50% of the maximum SUV plus 10mm margin was the best subvolume for dose boosting due to high coverage of primary site NVs (92.3%), low average relative volume to CTV1 (41%), and least average percent voxels outside CTV1 (19%).

CONCLUSIONS

The majority of loco-regional recurrences originate in the regions of central-high-dose. When correlated with pretreatment FDG-PET, the majority of recurrences originated in an area that would be covered by additional 10mm margin on the volume of 50% of the maximum FDG uptake.

Methodology for analysis and reporting patterns of failure in the Era of IMRT: head and neck cancer applications

Background

The aim of this study is to develop a methodology to standardize the analysis and reporting of the patterns of loco-regional failure after IMRT of head and neck cancer.

Material and Methods

Twenty-one patients with evidence of local and/or regional failure following IMRT for head-and-neck cancer were retrospectively reviewed under approved IRB protocol. Manually delineated recurrent gross disease (rGTV) on the diagnostic CT documenting recurrence (rCT) was co-registered with the original planning CT (pCT) using both deformable (DIR) and rigid (RIR) image registration software. Subsequently, mapped rGTVs were compared relative to original planning target volumes (TVs) and dose using a centroid-based approaches. Failures were then classified into five types based on combined spatial and dosimetric criteria; A (central high dose), B (peripheral high dose), C (central elective dose), D (peripheral elective dose), and E (extraneous dose).

Results

A total of 26 recurrences were identified. Using DIR, recurrences were assigned to more central TVs compared to RIR as detected using the spatial centroid-based method (p = 0.0002). rGTVs mapped using DIR had statistically significant higher mean doses when compared to rGTVs mapped rigidly (mean dose 70 vs. 69 Gy, p = 0.03). According to the proposed classification 22 out of 26 failures were of type A (central high dose) as assessed by DIR method compared to 18 out of 26 for the RIR because of the tendencey of RIR to assign failures more peripherally.

Conclusions

RIR tends to assigns failures more peripherally. DIR-based methods showed that the vast majority of failures originated in the high dose target volumes and received full prescribed doses suggesting biological rather than technology-related causes of failure. Validated DIR-based registration is recommended for accurate failure characterization and a novel typology-indicative taxonomy is recommended for failure reporting in the IMRT era.

Electronic supplementary material

The online version of this article (doi:10.1186/s13014-016-0678-7) contains supplementary material, which is available to authorized users.

Development and Validation of a Small Animal Immobilizer and Positioning System for the Study of Delivery of Intracranial and Extracranial Radiotherapy Using the Gamma Knife System

The purpose of this research is to establish a process of irradiating mice using the Gamma Knife as a versatile system for small animal irradiation and to validate accurate intracranial and extracranial dose delivery using this system. A stereotactic immobilization device was developed for small animals for the Gamma Knife head frame allowing for isocentric dose delivery. Intercranial positional reproducibility of a reference point from a primary reference animal was verified on an additional mouse. Extracranial positional reproducibility of the mouse aorta was verified using 3 mice. Accurate dose delivery was validated using film and thermoluminescent dosimeter measurements with a solid water phantom. Gamma Knife plans were developed to irradiate intracranial and extracranial targets. Mice were irradiated validating successful targeted radiation dose delivery. Intramouse positional variability of the right mandible reference point across 10 micro-computed tomography scans was 0.65 ± 0.48 mm. Intermouse positional reproducibility across 2 mice at the same reference point was 0.76 ± 0.46 mm. The accuracy of dose delivery was 0.67 ± 0.29 mm and 1.01 ± 0.43 mm in the coronal and sagittal planes, respectively. The planned dose delivered to a mouse phantom was 2 Gy at the 50% isodose with a measured thermoluminescent dosimeter dose of 2.9 ± 0.3 Gy. The phosphorylated form of member X of histone family H2A (γH2AX) staining of irradiated mouse brain and mouse aorta demonstrated adjacent tissue sparing. In conclusion, our system for preclinical studies of small animal irradiation using the Gamma Knife is able to accurately deliver intracranial and extracranial targeted focal radiation allowing for preclinical experiments studying focal radiation.

Application of positron emission tomography/computed tomography in radiation treatment planning for head and neck cancers

18-fluorodeoxygluocose positron emission tomography/computed tomography (¹⁸FDG-PET/CT) provides significant information in multiple settings in the management of head and neck cancers (HNC). This article seeks to define the additional benefit of PET/CT as related to radiation treatment planning for squamous cell carcinomas (SCCs) of the head and neck through a review of relevant literature. By helping further define both primary and nodal volumes, radiation treatment planning can be improved using PET/CT. Special attention is paid to the independent benefit of PET/CT in targeting mucosal primaries as well as in detecting nodal metastases. The utility of PET/CT is also explored for treatment planning in the setting of SCC of unknown primary as PET/CT may help define a mucosal target volume by guiding biopsies for examination under anesthesia thus changing the treatment paradigm and limiting the extent of therapy. Implications of the use of PET/CT for proper target delineation in patients with artifact from dental procedures are discussed and the impact of dental artifact on CT-based PET attenuation correction is assessed. Finally, comment is made upon the role of PET/CT in the high-risk post-operative setting, particularly in the context of radiation dose escalation. Real case examples are used in these settings to elucidate the practical benefits of PET/CT as related to radiation treatment planning in HNCs.

Characteristics and kinetics of cervical lymph node regression after radiation therapy for human papillomavirus-associated oropharyngeal carcinoma: quantitative image analysis of post-radiotherapy response

BACKGROUND AND PURPOSE

We sought to characterize the pattern of lymph node regression and morphology following definitive radiation therapy (RT) for human papilloma virus (HPV)-associated oropharyngeal carcinoma in patients with disease control.

MATERIALS AND METHODS

Radiographically positive cervical lymph nodes from patients treated with definitive RT for HPV-associated oropharyngeal carcinoma were segmented on initial pre- and subsequent post-RT contrast enhanced CT images. Pre-specified quantitative nodal parameters were calculated. Initial nodal parameter correlates of final nodal size, final nodal volume, and time to <1 cm short-axis diameter were determined.

RESULTS

Sixty-six radiographically positive lymph node were analyzed in 36 patients. Lymph nodes exhibited initial volume decreases with size stabilization at ∼4 months. Fifteen nodes (23%) underwent complete radiographic response (median 6.4 months following RT; range 2.9-25.6 months). On multivariate time-to-event analysis, initial hypodense/fat component, nodal volume, and short-axis diameter exhibited inverse association, while higher HU standard deviation exhibited a positive association, with reaching <1 cm short-axis diameter (all p<0.05).

CONCLUSIONS

Our results showed a substantial decrease in nodal volume within the first 1-2 months following RT. These findings support our current nodal imaging paradigm, propose a quantitative methodology, and describe a reference dataset for further validation and comparison studies.

Quality assurance assessment of diagnostic and radiation therapy-simulation CT image registration for head and neck radiation therapy: anatomic region of interest-based comparison of rigid and deformable algorithms

PURPOSE

To develop a quality assurance (QA) workflow by using a robust, curated, manually segmented anatomic region-of-interest (ROI) library as a benchmark for quantitative assessment of different image registration techniques used for head and neck radiation therapy-simulation computed tomography (CT) with diagnostic CT coregistration.

MATERIALS AND METHODS

Radiation therapy-simulation CT images and diagnostic CT images in 20 patients with head and neck squamous cell carcinoma treated with curative-intent intensity-modulated radiation therapy between August 2011 and May 2012 were retrospectively retrieved with institutional review board approval. Sixty-eight reference anatomic ROIs with gross tumor and nodal targets were then manually contoured on images from each examination. Diagnostic CT images were registered with simulation CT images rigidly and by using four deformable image registration (DIR) algorithms: atlas based, B-spline, demons, and optical flow. The resultant deformed ROIs were compared with manually contoured reference ROIs by using similarity coefficient metrics (ie, Dice similarity coefficient) and surface distance metrics (ie, 95% maximum Hausdorff distance). The nonparametric Steel test with control was used to compare different DIR algorithms with rigid image registration (RIR) by using the post hoc Wilcoxon signed-rank test for stratified metric comparison.

RESULTS

A total of 2720 anatomic and 50 tumor and nodal ROIs were delineated. All DIR algorithms showed improved performance over RIR for anatomic and target ROI conformance, as shown for most comparison metrics (Steel test, P < .008 after Bonferroni correction). The performance of different algorithms varied substantially with stratification by specific anatomic structures or category and simulation CT section thickness.

CONCLUSION

Development of a formal ROI-based QA workflow for registration assessment demonstrated improved performance with DIR techniques over RIR. After QA, DIR implementation should be the standard for head and neck diagnostic CT and simulation CT allineation, especially for target delineation.

Late radiation-associated dysphagia (late-RAD) with lower cranial neuropathy after oropharyngeal radiotherapy: a preliminary dosimetric comparison

BACKGROUND AND OBJECTIVES

Late radiation-associated dysphagia (late-RAD) is a rare delayed toxicity, in oropharyngeal cancer (OPC) survivors. Prevention of late-RAD is paramount because the functional impairment can be profound and refractory to standard therapies. The objective of this analysis is to identify candidate dosimetric predictors of late-RAD and associated lower cranial neuropathies after radiotherapy (RT) or chemo-RT (CRT) for OPC.

MATERIALS AND METHODS

An unmatched retrospective case-control analysis was conducted. Late-RAD cases were identified among OPC patients treated with definitive RT or CRT. Controls were selected with minimum of 6 years without symptoms of late-RAD. Dysphagia-aspiration related structures (DARS) and regions of interest containing cranial nerve paths (RCCNPs) were retrospectively contoured. Dose volume histograms were calculated. Non-parametric bivariate associations were analyzed with Bonferroni correction and multiple logistic regression models were fit.

RESULTS

Thirty-eight patients were included (12 late-RAD cases, 26 controls). Median latency to late-RAD was 5.8 years (range: 4.5-11.3 years). Lower cranial neuropathies were present in 10 of 12 late-RAD cases. Mean superior pharyngeal constrictor (SPC) dose was higher in cases relative to controls (median: 70.5 vs. 61.6 Gy). Mean SPC dose significantly predicted late-RAD (p = 0.036) and related cranial neuropathies (p = 0.019). RCCNPs did not significantly predict late-RAD or cranial neuropathies.

CONCLUSIONS

SPC dose may predict for late-RAD and related lower cranial neuropathies. These data, and those of previous studies that have associated SPC dose with classical dysphagia endpoints, suggest impetus to constrain dose to the SPCs when possible.

Estimation of daily interfractional larynx residual setup error after isocentric alignment for head and neck radiotherapy: quality assurance implications for target volume and organs-at-risk margination using daily CT on- rails imaging

Larynx may alternatively serve as a target or organs at risk (OAR) in head and neck cancer (HNC) image-guided radiotherapy (IGRT). The objective of this study was to estimate IGRT parameters required for larynx positional error independent of isocentric alignment and suggest population-based compensatory margins. Ten HNC patients receiving radiotherapy (RT) with daily CT on-rails imaging were assessed. Seven landmark points were placed on each daily scan. Taking the most superior-anterior point of the C5 vertebra as a reference isocenter for each scan, residual displacement vectors to the other six points were calculated postisocentric alignment. Subsequently, using the first scan as a reference, the magnitude of vector differences for all six points for all scans over the course of treatment was calculated. Residual systematic and random error and the necessary compensatory CTV-to-PTV and OAR-to-PRV margins were calculated, using both observational cohort data and a bootstrap-resampled population estimator. The grand mean displacements for all anatomical points was 5.07 mm, with mean systematic error of 1.1 mm and mean random setup error of 2.63 mm, while bootstrapped POIs grand mean displacement was 5.09 mm, with mean systematic error of 1.23 mm and mean random setup error of 2.61 mm. Required margin for CTV-PTV expansion was 4.6 mm for all cohort points, while the bootstrap estimator of the equivalent margin was 4.9 mm. The calculated OAR-to-PRV expansion for the observed residual setup error was 2.7 mm and bootstrap estimated expansion of 2.9 mm. We conclude that the interfractional larynx setup error is a significant source of RT setup/delivery error in HNC, both when the larynx is considered as a CTV or OAR. We estimate the need for a uniform expansion of 5 mm to compensate for setup error if the larynx is a target, or 3 mm if the larynx is an OAR, when using a nonlaryngeal bony isocenter.

Health status and renal function evaluation of kidney vendors: a report from Pakistan

Unrelated kidney transplants have lead to commerce and kidney vending in Pakistan. This study on 104 vendors reports demographics, history, physical and systemic examination, ultrasound findings, renal and liver function and GFR by Cockcroft-Gault. Results were compared with 184 age, sex and nephrectomy duration matched living-related donors controls. Comparison of vendors versus controls showed mean age of 30.55 +/- 8.1 versus 30.65 +/- 7.85 (p = 0.91) years, M:F of 4.5:1 versus 4.2:1 and nephrectomy period of 33.89 +/- 30 versus 32.01 +/- 29.71 (p = 0.60) months respectively. Of the vendors 67% were bonded laborers earning <50 $/month as compared to controls where 68% were skilled laborers and self-employed earning >100 $/month. History of vendors revealed jaundice in 8%, stone disease in 2% and urinary tract symptoms in 4.8%. Postnephrectomy findings between vendors versus donors showed BMI of 21.02 +/- 2.8 versus 23.02 +/- 4.2 (p = 0.0001), hypertension in 17% versus 9.2% (p = 0.04), serum creatinine (mg/dL) of 1.17+/-0.21 versus 1.02 +/- 0.27 (p = 0.0001), GFR (mL/min) of 70.94 +/- 14.2 versus 95.4 +/- 20.44 (p = 0.0001), urine protein/creatinine of 0.150 +/- 0.109 versus 0.10 +/- 0.10 (p = 0.0001), hepatitis C positivity in 27% versus 1.0% (p = 0.0001) and hepatitis B positive 5.7% versus 0.5% (p = 0.04), respectively. In conclusion, vendors had compromised renal function suggesting inferior selection and high risk for developing chronic kidney disease in long term.