Precision Radiotherapy: Reduction in Radiation for Oropharyngeal Cancer in the 30 ROC Trial

Optimizing fractionation schedules for de-escalation radiotherapy in head and neck cancers using deep reinforcement learning

PURPOSE

Patients with locally-advanced head and neck squamous cell carcinomas (HNSCCs), particularly those related to human papillomavirus (HPV), often achieve good locoregional control (LRC), yet they suffer significant toxicities from standard chemoradiotherapy. This study aims to optimize the daily dose fractionation based on individual responses to radiotherapy (RT), minimizing toxicity while maintaining a low risk of LRC failure.

METHOD

A virtual environment was developed to simulate tumor dynamics under RT for optimizing dose schedules. Patients predicted to maintain LRC were selected for de-escalation experiments. The proliferation saturation index (PSI) and linear-quadratic model were used to predict responses. A deep reinforcement learning (DRL) agent optimized fractionation schemes by interacting with the simulation environment, aiming to reduce the OAR's biologically effective dose (BED) while preserving LRC. The impact of model uncertainty was analyzed and a support vector machine (SVM) model was used to segment parameter space and identify patients more robust to noise.

RESULTS

Personalized de-escalation plans were compared to conventional RT in a cohort of 5000 virtual patients. Personalized fractionation reduced the tumor dose and OAR's BED by 29%, with an average OAR BED reduction of 5.61 ± 2.96 Gy. Prognostic outcomes were nearly identical, with 99.80% of patients in the low-risk LRC failure group. Model uncertainty impacted dosimetric indicators and prognosis, but the high-BED benefit group showed greater robustness to noise. SVM decision boundaries defined parameters range for patient selection.

CONCLUSION

Optimizing fractionated doses based on patient responses minimizes toxicity while maintaining LRC in HNSCCs. Stratifying patients can mitigate model uncertainty and reduce treatment risks.

Extra-capsular nodal extension after surgical resection for HPV-positive oropharyngeal Cancer: Adjuvant radiation versus chemoradiation

PURPOSE

The prognostic significance of extra-capsular nodal extension (ECE) after surgical resection for human papillomavirus (HPV)-positive oropharyngeal cancer is controversial, and the optimal choice of adjuvant therapy is uncertain in this setting.

METHODS AND MATERIALS

A review of institutional databases identified a total of 63 patients with pathological evidence of ECE in at least 1 cervical lymph node after transoral robotic surgery and neck dissection for HPV-positive squamous cell carcinoma of the oropharynx. Clinical outcomes were compared based on whether patients received adjuvant radiation (20 patients) or chemoradiation (43 patients). The Kaplan Meier method was used to determine survival statistics with comparisons between groups conducted with the log-rank test.

RESULTS

With a median follow-up of 50 months (range, 6 to 110 months), the 3-year overall survival for the entire population was 87 %. No significant difference was observed between patients treated by adjuvant radiation and chemoradiation with respect to 3-year overall survival (86 % versus 87 %, p = 0.45), local-regional control (91 % vs. 90 %, p = 0.71), and progression-free survival (83 % vs. 85 %, p = 0.57). Exploratory subset analysis of competing variables failed to identify any group in which the addition of chemotherapy to radiation improved outcome.

CONCLUSIONS

While the presence of ECE after surgical resection has historically been considered an indication for the use of concurrent chemoradiation in the adjuvant setting, these data suggest that this paradigm should be re-evaluated in the setting of HPV-positive oropharyngeal cancer.

De-escalated Management of HPV-positive Oropharyngeal Carcinoma: Improving Outcomes with Personalized Approaches

Human papilloma virus (HPV)-positive oropharyngeal cancer (OPC) is increasingly prevalent and has a favorable prognosis compared to HPV-negative OPC and other head and neck malignancies associated with smoking and alcohol. De-escalation of definitive therapy for HPV-positive OPC is an attractive strategy aiming to maintain oncologic efficacy while reducing short-term and long-term toxicities and improving quality of life. In this article, we outline approaches to de-escalation including use of alternative systemic therapies, reduction in dose of systemic therapy, and reductions in radiation dose and/or volume. We also highlight successes and cautionary outcomes from de-escalation studies and advocate for a personalized approach to future de-escalation trials in HPV-positive OPC.

Redefining Candidates for Deintensification in Locoregionally Advanced P16+ Oropharyngeal Cancer Based on Relative Risk

PURPOSE

Randomized trials have found that patients with locoregionally advanced p16+ oropharyngeal squamous cell carcinoma (OPSCC) do not benefit from treatment deintensification, even among favorable risk groups. Although various methods have been used to identify candidates for treatment deintensification, the optimal approach is unknown.

METHODS AND MATERIALS

We conducted a multi-institutional cohort study of 444 patients with previously untreated p16+ OPSCC undergoing definitive radiation therapy with or without systemic therapy between 2009 and 2022. We compared the following 2 approaches for identifying candidates for deintensification: (1) favorable versus unfavorable risk, using NRG-HN005 eligibility criteria, and (2) low versus high relative risk of cancer events, using the Head and Neck Cancer Intergroup predictive classifier ("omega score"). We tested differences in outcomes and systemic therapy allocation by risk group using multivariable Cox models, competing event models, and logistic regression, and compared characteristics of hypothetical deintensification trials using the 2 approaches. Progression-free survival events were defined as cancer recurrence (locoregional or distant) or death from any cause.

RESULTS

Median follow-up time was 52 months; 120 patients (27.0%) were favorable risk; a different 120 patients had low omega score; 28 patients (6.3%) met both criteria; 184 patients (41.4%) had discordant classification. On ordinal logistic regression, decreasing omega score was associated with a statistically significantly lower odds of receiving intensive therapy (normalized odds ratio, 0.37 per SD; 95% CI, 0.24-0.57), with a greater magnitude than favorable risk group (odds ratio, 0.66; 95% CI, 0.44-0.99). Among patients receiving cisplatin and/or platinum-based induction (n = 374), favorable risk was associated with significantly improved progression-free survival (hazard ratio, 0.59; 95% CI, 0.36-0.99), whereas lower omega score was associated with a significantly decreased relative hazard for cancer events (relative hazard ratio, 0.18; 95% CI, 0.070-0.46). In simulations, selecting patients with low omega scores increased the efficiency of hypothetical noninferiority trials.

CONCLUSIONS

Considering patients' relative risk of cancer events can help define optimal populations for treatment deintensification in p16+ OPSCC.

Optimising hypoxia PET imaging and its applications in guiding targeted radiation therapy for non-small cell lung cancer: a scoping review

INTRODUCTION

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death. Definitive treatment includes chemotherapy and radiation therapy. Tumour hypoxia impacts the efficacy of these treatment modalities. Novel positron-emission tomography (PET) imaging has been developed to non-invasively quantify hypoxic tumour subregions, and to guide personalised treatment strategies. This review evaluates the reliability of hypoxia imaging in NSCLC in relation to various tracers, its correlations to treatment-related outcomes, and to assess if this imaging modality can be meaningfully applied into radiation therapy workflows.

METHODS

A literature search was conducted on the Medline (Ovid) and Embase databases. Searches included terms related to 'hypoxia', 'positron-emission tomography', 'magnetic resonance imaging' and 'lung cancer'. Results were filtered to exclude studies prior to 2011, and animal studies were excluded. Only studies referring to a confirmed pathology of NSCLC were included, while disease staging was not a limiting factor. Full-text English language and translated literature examined included clinical trials, clinical cohort studies and feasibility studies.

RESULTS

Quantification of hypoxic volumes in a pre-treatment setting is of prognostic value, and indicative of treatment response. Dosimetric comparisons have highlighted potential to significantly dose escalate to hypoxic volumes without risk of additional toxicity. However, clinical data to support these strategies are lacking.

CONCLUSION

Heterogenous study design and non-standardised imaging parameters have led to a lack of clarity regarding the application of hypoxia PET imaging in NSCLC. PET imaging using nitroimidazole tracers is the most investigated method of non-invasively measuring tumour hypoxia and has potential to guide hypoxia-targeted radiation therapy. Further clinical research is required to elucidate the benefits versus risks of dose-escalation strategies.

Treatment strategies in human papillomavirus-related advanced penile cancer

Penile cancer is a rare neoplasm with heterogeneous prevalence influenced by risk factors such as smoking, poor hygiene and human papillomavirus (HPV) infection. Southern Africa, South America and Southeast Asia have the highest incidence of this disease. Penile squamous cell carcinomas (PSCCs) account for the majority of instances of penile cancer, with HPV-related carcinogenesis implicated in up to half of them. Increases in PSCC incidence in industrialized nations parallel the rising high-risk HPV infection rates, particularly HPV-16. Early-stage, localized PSCC is often manageable, but treatment options in advanced disease remain limited, with poor survival outcomes. Emerging evidence suggests that HPV-positive PSCC might exhibit unique therapeutic responses, including increased sensitivity to radiotherapy and chemotherapy, as has been observed in HPV-driven head and neck squamous cell carcinoma. Results of studies in HPV-positive PSCC demonstrate improved responses to chemoradiotherapy and immunotherapy, underscoring the potential for tailored treatments and de-escalation. Additionally, incorporating immunotherapy with radiotherapy in HPV-driven PSCC might provide greater oncological benefits than standard chemotherapy. These observations suggest that treatment strategies for HPV-positive PSCC might benefit from de-escalated chemoradiotherapy regimens or immunotherapy incorporation, potentially optimizing efficacy while minimizing toxic effects. Furthermore, biomarkers such as tumour mutational burden, programmed cell death ligand 1 expression, and genetic alterations could be crucial for predicting treatment response. Comprehensive biomarker assessment and accurate HPV status determination are essential for developing patient-tailored therapeutic strategies. These data provide evidence of the potential benefits of individualized approaches based on tumour biology and biomarker profiles.

Online Radiotherapy: The Paradigm Shift to Real-Time Adaptive Radiotherapy

BACKGROUND

Adaptive radiotherapy (ART) involves the continuous adaptation of the radiation plan according to patient- and tumorspecific feedback. In online ART, the plan is optimized in real time during the treatment; in offline ART, the plan is recalculated between treatment sessions. Hybrid linear accelerators with integrated CT, MRI, or PET are required to perform online ART.

METHODS

This review is based on clinically relevant studies on online ART (January 2019 - May 2024) that were retrieved by a selective search in PubMed.

RESULTS

Online ART is a new technique for which no phase 3 trials have been published; in contrast, multiple randomized trials are already available for offline ART. The initial findings of a random - ized phase 2 trial of online ART for head and neck cancer showed lower rates of G2 or higher radiation-induced dermatitis (8% vs. 31%, p = 0.05) and a lower dose to the parotid gland (mean dose: 11.5 Gy vs. 16.0 Gy, p = 0.02) with online ART compared to standard radiochemotherapy. Moreover, observational studies show that online ART is feasible and spares organs at risk in patients with esophageal, pancreatic, rectal, and prostatic cancer. Additionally, online ART can enable simulation-free treatment planning and faster initiation of radiotherapy. It is, however, more demanding of time and resources and more costly than standard radiotherapy, and no studies with long-term clinical endpoints are available to date.

CONCLUSION

Initial studies confirm the feasibility of online ART and arouse the hope that it will enable more precise radiotherapy with less damage to surrounding structures. Phase 3 trials are needed so that the patient groups who stand to benefit most from online ART can be identified.

Oxygen-Enhanced MRI Detects Incidence, Onset, and Heterogeneity of Radiation-Induced Hypoxia Modification in HPV-Associated Oropharyngeal Cancer

PURPOSE

Hypoxia mediates treatment resistance in solid tumors. We evaluated if oxygen-enhanced MRI-derived hypoxic volume (HVMRI) is repeatable and can detect radiotherapy-induced hypoxia modification in human papillomavirus-associated oropharyngeal head and neck squamous cell cancer.

EXPERIMENTAL DESIGN

A total of 27 patients were recruited prospectively between March 2021 and January 2024. HVMRI was measured in primary and nodal tumors prior to standard-of-care (chemo)radiotherapy and then at weeks 2 and 4 (W2 and W4) into therapy. Two pretreatment scans assessed biomarker within-subject coefficient of variation and repeatability coefficient (RC). Cohort treatment response was measured using mixed-effects modeling. Responding lesions were identified by comparing HVMRI change with RC limits of agreement.

RESULTS

Oxygen-enhanced MRI identified hypoxia in all lesions. The HVMRI within-subject coefficient of variation was 24.6%, and RC limits of agreement were -45.7% to 84.1%. A cohort median pretreatment HVMRI of 11.3 cm3 reduced to 6.9 cm3 at W2 and 5.9 cm3 at W4 (both P < 0.001). HVMRI was reduced in 54.5% of individual lesions by W2 and in 88.2% by W4. All lesions with W2 hypoxia reduction showed persistent modification at W4. HVMRI reduced in some lesions that showed no overall volume change. Hypoxia modification was discordant between primary and nodal tumors in 50.0% of patients.

CONCLUSIONS

Radiation-induced hypoxia modification can occur as early as W2, but onset varies between patients and was not necessarily associated with overall size change. Half of all patients had discordant changes in primary and nodal tumors. These findings have implications for patient selection and timing of dose de-escalation strategies in human papillomavirus-associated oropharyngeal carcinoma. See related commentary by Mason, p. 5503.

Interpretable survival network for progression risk analysis of multimodality imaging biomarkers in poor-prognosis head and neck cancers

This study explores the predictive utility of multi-time point, multi-modality quantitative imaging biomarkers (QIBs) and clinical factors in patients with poor-prognosis head and neck cancers (HNCs) using interpretable machine learning. We examined 93 patients with p16 + oropharyngeal squamous cell carcinoma or locally advanced p16- HNCs enrolled in a phase II adaptive radiation dose escalation trial. FDG-PET and multiparametric MRI scans were conducted before radiation therapy and at the 10th fraction (2 weeks). A survival network analyzed MRI and PET-derived biomarkers such as gross tumor volume (GTV), blood volume (BV), and metabolic tumor volume (MTV50), along with clinical factors to predict local (LF) and distant failures (DF). Feature attributions and interactions were assessed using Expected Gradients (EG) and Expected Hessian (EH). Through rigorous cross-validation, the model for predicting LF, incorporating biomarkers like p16 status and radiation boost, achieved a c-index of 0.758. Similarly, the DF prediction model showed a c-index of 0.695. The analysis of feature attributions and interactions enhanced understanding of important features and complex factor interplays, potentially guiding more personalized and intensified treatment approaches for HNC patients.

Loss of MACROD2 drives radioresistance but not cisplatin resistance in HPV-positive head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer type worldwide. In recent years, there has been an increase in the rate of HNSCC cases attributed to the infection of the oropharynx by the human papillomavirus (HPV). Given the significant treatment-related toxicities of the current standard of care for HPV-positive HNSCC, there is an urgent need for the development of precision patient stratification and treatment strategies to improve patients' quality of life while maintaining excellent survival rates. We have previously carried out whole genome sequencing of HPV+ HNSCC tumors that failed concurrent cisplatin and radiation treatment and discovered that MACROD2 deletion is enriched among these tumors. In the current study, we sought to investigate the mechanistic role of MACROD2 in HPV+ HNSCC treatment resistance. Our results indicate that MACROD2 depletion in HNSCC cell lines leads to increased cell viability and colony formation capacity. Interestingly, MACROD2 depletion did not alter cisplatin sensitivity but led to an increase in radiation resistance of HPV+ HNSCC cell lines. RNA sequencing and immunofluorescence microscopy demonstrated that MACROD2-depleted HPV+ HNSCC cells displayed elevated levels of hypoxia and an altered DNA damage response. Taken together, this study establishes and characterizes the role of MACROD2 in HPV+ HNSCC radioresistance. Further work is needed to validate MACROD2 as a biomarker of treatment failure and to understand how to overcome the identified molecular mechanisms of resistance.

Can we safely de-escalate HPV+ oropharyngeal cancers? - A review of current practices and novel approaches

Oropharyngeal carcinomas linked to high-risk types of human papillomavirus (HPV+OPC) as a distinct tumor entity, have a better prognosis than HPV-OPC. Current treatment approaches do not differentiate between HPV-positive and negative disease, but ongoing studies are exploring de-escalation strategies, aiming to reduce therapy-related morbidity and improve patient quality of life, particularly focusing on reducing late effects from radiotherapy.We performed a literature search for both published and ongoing clinical trials and critically discussed the presented concepts and results. Those include reduction in radiotherapy dose or volume, omission or modification of concomitant chemotherapy/immunotherapy, usage of induction chemotherapy and utilization of advanced molecular and imaging biomarkers and radiomics for selected subgroups of HPV+OPC patients. While promising data have been reported from various Phase II trials, evidence from Phase III de-escalation trials has failed to demonstrate improved outcomes. Therefore, further data and an improved risk stratification are required before de-escalated radiation treatments can be recommended outside of clinical trials.The review aims to outline current de-escalation strategies and future possibilities for enhancing patient outcomes in HPV+OPC.

Conference Report: Review of Clinical Implementation of Advanced Quantitative Imaging Techniques for Personalized Radiotherapy

The topic of quantitative imaging in radiation therapy was presented as a "Masterclass" at the 2023 annual meeting of the American Society of Radiation Oncology (ASTRO). Dual-energy computed tomography (CT) and single-positron computed tomography were reviewed in detail as the first portion of the meeting session, with data showing utility in many aspects of radiation oncology including treatment planning and dose response. Positron emission tomography/CT scans evaluating the functional volume of lung tissue so as to provide optimal avoidance of healthy lungs were presented second. Advanced brain imaging was then discussed in the context of different forms of magnetic resonance scanning methods as the third area noted with significant discussion of ongoing research programs. Quantitative image analysis was presented to provide clinical utility for the analysis of patients with head and neck cancer. Finally, quality assurance was reviewed for different forms of quantitative imaging given the critical nature of imaging when numerical valuation, not just relative contrast, plays a crucial role in clinical process and decision-making. Conclusions and thoughts are shared in the conclusion, noting strong data supporting the use of quantitative imaging in radiation therapy going forward and that more studies are needed to move the field forward.

Painful Realities: Navigating the Complexities of Head and Neck Cancer Pain

BACKGROUND

Head and neck cancer (HNC) and its treatments can cause significant pain, which can profoundly impact patients' quality of life and treatment outcomes. Understanding the full scope of HNC pain is essential for effective management and improved patient care.

OBJECTIVE

This review aims to comprehensively analyze the multifaceted nature of pain experienced by individuals with HNC, including its various etiologies and management strategies.

RESULTS

HNC pain can arise from tumor extent, treatment-related toxicity, or comorbid conditions. The pathophysiology involves complex interactions between nociceptive, neuropathic, and inflammatory mechanisms. Optimal pain control requires a multimodal patient-tailored approach utilizing both pharmacological and non-pharmacological therapies.

CONCLUSION

Enhancing our understanding of HNC pain and optimizing its management is imperative for improving the overall well-being and treatment outcomes of affected individuals. Future research should focus on understanding detailed pain mechanisms, with the goal of developing personalized pain management strategies and exploring novel therapeutic targets. By implementing comprehensive approaches to HNC pain management, healthcare providers can better support patients through their cancer treatment journey.

Treatment De-escalation in Oropharyngeal Carcinoma and the Role of Robotic Surgery

Oropharyngeal squamous cell carcinoma (OPSCC) related to human papillomavirus (HPV) infection has better survival outcomes compared to non-HPV-related OPSCC, leading to efforts to de-escalate the intensity of treatment to reduce associated morbidity. This article reviews recent clinical efforts to explore different de-escalation frameworks with a particular emphasis on the emergence of transoral robotic surgery and surgically driven de-escalation approaches. It discusses the current evidence for incorporating surgery into an evolving treatment paradigm for HPV-related OPSCC.

Development of 18F-Fluoromisonidazole Hypoxia PET/CT Diagnostic Interpretation Criteria and Validation of Interreader Reliability, Reproducibility, and Performance

Tumor hypoxia, an integral biomarker to guide radiotherapy, can be imaged with 18F-fluoromisonidazole (18F-FMISO) hypoxia PET. One major obstacle to its broader application is the lack of standardized interpretation criteria. We sought to develop and validate practical interpretation criteria and a dedicated training protocol for nuclear medicine physicians to interpret 18F-FMISO hypoxia PET. Methods: We randomly selected 123 patients with human papillomavirus-positive oropharyngeal cancer enrolled in a phase II trial who underwent 123 18F-FDG PET/CT and 134 18F-FMISO PET/CT scans. Four independent nuclear medicine physicians with no 18F-FMISO experience read the scans. Interpretation by a fifth nuclear medicine physician with over 2 decades of 18F-FMISO experience was the reference standard. Performance was evaluated after initial instruction and subsequent dedicated training. Scans were considered positive for hypoxia by visual assessment if 18F-FMISO uptake was greater than floor-of-mouth uptake. Additionally, SUVmax was determined to evaluate whether quantitative assessment using tumor-to-background ratios could be helpful to define hypoxia positivity. Results: Visual assessment produced a mean sensitivity and specificity of 77.3% and 80.9%, with fair interreader agreement (κ = 0.34), after initial instruction. After dedicated training, mean sensitivity and specificity improved to 97.6% and 86.9%, with almost perfect agreement (κ = 0.86). Quantitative assessment with an estimated best SUVmax ratio threshold of more than 1.2 to define hypoxia positivity produced a mean sensitivity and specificity of 56.8% and 95.9%, respectively, with substantial interreader agreement (κ = 0.66), after initial instruction. After dedicated training, mean sensitivity improved to 89.6% whereas mean specificity remained high at 95.3%, with near-perfect interreader agreement (κ = 0.86). Conclusion: Nuclear medicine physicians without 18F-FMISO hypoxia PET reading experience demonstrate much improved interreader agreement with dedicated training using specific interpretation criteria.

Tumor Hypoxia on 18F-fluoromisonidazole Positron Emission Tomography and Distant Metastasis From Head and Neck Squamous Cell Carcinoma

Importance

Given high rates of locoregional control after definitive management of head and neck squamous cell carcinoma (HNSCC), better methods are needed to project distant metastasis (DM) risk. Tumor hypoxia on 18F-fluoromisonidazole (FMISO) positron emission tomography (PET) is associated with locoregional failure, but data demonstrating an association with DM are limited.

Objective

To determine whether tumor hypoxia on FMISO PET is associated with DM risk after chemoradiotherapy (CRT) for HNSCC.

Design, Setting, and Participants

This cohort study assessed patients with HNSCC enrolled in 2 prospective clinical trials at a single academic referral center from 2004 to 2021 in which participants received FMISO PET before and during CRT. Data analysis occurred from May 2023 to May 2024.

Exposures

FMISO PET scans before and 1 to 2 weeks after starting CRT were evaluated for tumor hypoxia by nuclear medicine physicians.

Main Outcomes and Measures

The primary outcome was DM, defined as biopsy-proven HNSCC outside the primary site and regional lymph nodes. Time to DM was modeled with competing risk regression, with death as a competing risk. Overall survival (OS) was assessed secondarily and modeled with Cox regression.

Results

Among 281 patients (median [range] age at CRT, 58.7 [25.5-85.6] years; 251 male [89.3%]) included in this study, 242 (86.1%) had oropharyngeal primary cancer, and 266 (94.7%) had human papillomavirus-positive disease. Of all patients, 217 (77.2%) had T stage 1 or 2, and 231 patients (82.2%) had N stage 2b or less. De-escalated 30 Gy CRT was delivered to 144 patients (51.2%), and the remainder received standard 70 Gy CRT. On FMISO PET examination, 73 patients (26.0%) had hypoxia-negative disease before CRT, 138 patients (49.1%) had hypoxia-positive disease before CRT and then hypoxia-negative disease during CRT, and 70 patients (24.9%) persistently had hypoxia-positive disease before and during CRT. At a median (IQR) 58 (46-91) months of follow-up, 12 DM events and 22 deaths were observed. Persistent intratreatment hypoxia was associated with increased DM risk (hazard ratio, 3.51; 95% CI, 1.05-11.79; P = .04) and worse OS (hazard ratio, 2.66; 95% CI, 1.14-6.19; P = .02). No patients with hypoxia-negative disease before CRT experienced DM.

Conclusions and Relevance

In this cohort study using pooled analysis of prospective nonrandomized clinical trials incorporating FMISO PET in the definitive management of HNSCC, persistent intratreatment hypoxia was associated with increased risk of DM and worse OS. Conversely, all patients with hypoxia-negative disease before treatment remained free of DM. These findings suggest that pretreatment and intratreatment FMISO PET results may serve as biomarkers for DM risk and aid in identifying candidates for escalated therapeutic strategies.

Micronuclear collapse from oxidative damage

Chromosome-containing micronuclei are a hallmark of aggressive cancers. Micronuclei frequently undergo irreversible collapse, exposing their enclosed chromatin to the cytosol. Micronuclear rupture catalyzes chromosomal rearrangements, epigenetic abnormalities, and inflammation, yet mechanisms safeguarding micronuclear integrity are poorly understood. In this study, we found that mitochondria-derived reactive oxygen species (ROS) disrupt micronuclei by promoting a noncanonical function of charged multivesicular body protein 7 (CHMP7), a scaffolding protein for the membrane repair complex known as endosomal sorting complex required for transport III (ESCRT-III). ROS retained CHMP7 in micronuclei while disrupting its interaction with other ESCRT-III components. ROS-induced cysteine oxidation stimulated CHMP7 oligomerization and binding to the nuclear membrane protein LEMD2, disrupting micronuclear envelopes. Furthermore, this ROS-CHMP7 pathological axis engendered chromosome shattering known to result from micronuclear rupture. It also mediated micronuclear disintegrity under hypoxic conditions, linking tumor hypoxia with downstream processes driving cancer progression.

Clinical Experience With an Offline Adaptive Radiation Therapy Head and Neck Program: Dosimetric Benefits and Opportunities for Patient Selection

PURPOSE

The objective of this study was to develop a linear accelerator (LINAC)-based adaptive radiation therapy (ART) workflow for the head and neck that is informed by automated image tracking to identify major anatomic changes warranting adaptation. In this study, we report our initial clinical experience with the program and an investigation into potential trigger signals for ART.

METHODS AND MATERIALS

Offline ART was systematically performed on patients receiving radiation therapy for head and neck cancer on C-arm LINACs. Adaptations were performed at a single time point during treatment with resimulation approximately 3 weeks into treatment. Throughout treatment, all patients were tracked using an automated image tracking system called the Automated Watchdog for Adaptive Radiotherapy Environment (AWARE). AWARE measures volumetric changes in gross tumor volumes (GTVs) and selected normal tissues via cone beam computed tomography scans and deformable registration. The benefit of ART was determined by comparing adaptive plan dosimetry and normal tissue complication probabilities against the initial plans recalculated on resimulation computed tomography scans. Dosimetric differences were then correlated with AWARE-measured volume changes to identify patient-specific triggers for ART. Candidate trigger variables were evaluated using receiver operator characteristic analysis.

RESULTS

In total, 46 patients received ART in this study. Among these patients, we observed a significant decrease in dose to the submandibular glands (mean ± standard deviation: -219.2 ± 291.2 cGy, P < 10-5), parotids (-68.2 ± 197.7 cGy, P = .001), and oral cavity (-238.7 ± 206.7 cGy, P < 10-5) with the adaptive plan. Normal tissue complication probabilities for xerostomia computed from mean parotid doses also decreased significantly with the adaptive plans (P = .008). We also observed systematic intratreatment volume reductions (ΔV) for GTVs and normal tissues. Candidate triggers were identified that predicted significant improvement with ART, including parotid ΔV = 7%, neck ΔV = 2%, and nodal GTV ΔV = 29%.

CONCLUSIONS

Systematic offline head and neck ART was successfully deployed on conventional LINACs and reduced doses to critical salivary structures and the oral cavity. Automated cone beam computed tomography tracking provided information regarding anatomic changes that may aid patient-specific triggering for ART.

Loss of the DNA Repair Gene RNase H2 Identifies a Unique Subset of DDR-Deficient Leiomyosarcomas

Targeting the DNA damage response (DDR) pathway is an emerging therapeutic approach for leiomyosarcoma (LMS), and loss of RNase H2, a DDR pathway member, is a potentially actionable alteration for DDR-targeted treatments. Therefore, we designed a protein- and genomic-based RNase H2 screening assay to determine its prevalence and prognostic significance. Using a selective RNase H2 antibody on a pan-tumor microarray (TMA), RNase H2 loss was more common in LMS (11.5%, 9/78) than across all tumors (3.8%, 32/843). In a separate LMS cohort, RNase H2 deficiency was confirmed in uterine LMS (U-LMS, 21%, 23/108) and soft-tissue LMS (ST-LMS; 30%, 39/102). In the TCGA database, RNASEH2B homozygous deletions (HomDels) were found in 6% (5/80) of LMS cases, with a higher proportion in U-LMS (15%; 4/27) compared with ST-LMS (2%; 1/53). Using the SNiPDx targeted-NGS sequencing assay to detect biallelic loss of function in select DDR-related genes, we found RNASEH2B HomDels in 54% (19/35) of U-LMS cases with RNase H2 loss by IHC, and 7% (3/43) HomDels in RNase H2 intact cases. No RNASEH2B HomDels were detected in ST-LMS. In U-LMS patient cohort (n = 109), no significant overall survival difference was seen in patients with RNase H2 loss versus intact, or RNASEH2B HomDel (n = 12) versus Non-HomDel (n = 37). The overall diagnostic accuracy, sensitivity, and specificity of RNase H2 IHC for detecting RNA-SEH2B HomDels in U-LMS was 76%, 93%, and 71%, respectively, and it is being developed for future predictive biomarker driven clinical trials targeting DDR in U-LMS.

Multi-modality imaging parameters that predict rapid tumor regression in head and neck radiotherapy

Background and purpose

Volume regression during radiotherapy can indicate patient-specific treatment response. We aimed to identify pre-treatment multimodality imaging (MMI) metrics from positron emission tomography (PET), magnetic resonance imaging (MRI), and computed tomography (CT) that predict rapid tumor regression during radiotherapy in human papilloma virus (HPV) associated oropharyngeal carcinoma.

Materials and methods

Pre-treatment FDG PET-CT, diffusion-weighted MRI (DW-MRI), and intra-treatment (at 1, 2, and 3 weeks) MRI were acquired in 72 patients undergoing chemoradiation therapy for HPV+ oropharyngeal carcinoma. Nodal gross tumor volumes were delineated on longitudinal images to measure intra-treatment volume changes. Pre-treatment PET standardized uptake value (SUV), CT Hounsfield Unit (HU), and non-gaussian intravoxel incoherent motion DW-MRI metrics were computed and correlated with volume changes. Intercorrelations between MMI metrics were also assessed using network analysis. Validation was carried out on a separate cohort (N = 64) for FDG PET-CT.

Results

Significant correlations with volume loss were observed for baseline FDG SUVmean (Spearman ρ = 0.46, p < 0.001), CT HUmean (ρ = 0.38, p = 0.001), and DW-MRI diffusion coefficient, Dmean (ρ = -0.39, p < 0.001). Network analysis revealed 41 intercorrelations between MMI and volume loss metrics, but SUVmean remained a statistically significant predictor of volume loss in multivariate linear regression (p = 0.01). Significant correlations were also observed for SUVmean in the validation cohort in both primary (ρ = 0.30, p = 0.02) and nodal (ρ = 0.31, p = 0.02) tumors.

Conclusions

Multiple pre-treatment imaging metrics were correlated with rapid nodal gross tumor volume loss during radiotherapy. FDG-PET SUV in particular exhibited significant correlations with volume regression across the two cohorts and in multivariate analysis.

Neoadjuvant Nivolumab Plus Chemotherapy Followed By Response-Adaptive Therapy for HPV+ Oropharyngeal Cancer: OPTIMA II Phase 2 Open-Label Nonrandomized Controlled Trial

Importance

Immune checkpoint inhibitors improve survival in recurrent and/or metastatic head and neck cancer, yet their role in curative human papillomavirus-positive oropharyngeal cancer (HPV+ OPC) remains undefined. Neoadjuvant nivolumab and chemotherapy followed by response-adaptive treatment in HPV+ OPC may increase efficacy while reducing toxicity.

Objective

To determine the deep response rate and tolerability of the addition of neoadjuvant nivolumab to chemotherapy followed by response-adapted locoregional therapy (LRT) in patients with HPV+ OPC.

Design, Setting, and Participants

This phase 2 nonrandomized controlled trial conducted at a single academic center enrolled 77 patients with locoregionally advanced HPV+ OPC from 2017 to 2020. Data analyses were performed from February 10, 2021, to January 9, 2023.

Interventions

Addition of nivolumab to neoadjuvant nab-paclitaxel and carboplatin (studied in the first OPTIMA trial) followed by response-adapted LRT in patients with HPV+ OPC stages III to IV.

Main Outcomes and Measures

Primary outcome was deep response rate to neoadjuvant nivolumab plus chemotherapy, defined as the proportion of tumors with 50% or greater shrinkage per the Response Evaluation Criteria in Solid Tumors 1.1. Secondary outcomes were progression-free survival (PFS) and overall survival (OS). Swallowing function, quality of life, and tissue- and blood-based biomarkers, including programmed death-ligand 1 (PD-L1) expression and circulating tumor HPV-DNA (ctHPV-DNA), were also evaluated.

Results

The 73 eligible patients (median [range] age, 61 [37-82] years; 6 [8.2%] female; 67 [91.8%] male) started neoadjuvant nivolumab and chemotherapy. Deep responses were observed in 51 patients (70.8%; 95% CI, 0.59-0.81). Subsequent risk- and response-adaptive therapy was assigned as follows: group A, single-modality radiotherapy alone or transoral robotic surgery (28 patients); group B, intermediate-dose chemoradiotherapy of 45 to 50 Gray (34 patients); and group C, regular-dose chemoradiotherapy of 70 to 75 Gray (10 patients). Two-year PFS and OS were 90.0% (95% CI, 0.80-0.95) and 91.4% (95% CI, 0.82-0.96), respectively. By response-adapted group, 2-year PFS and OS for group A were 96.4% and 96.4%, and group B, 88.0% and 91.0%, respectively. Lower enteral feeding rates and changes in weight, as well as improved swallowing, were observed among patients who received response-adapted LRT. Pathologic complete response rate among patients who underwent transoral robotic surgery was 67.0%. PD-L1 expression was nonsignificantly higher for deeper responses and improved PFS, and ctHPV-DNA clearance was significantly associated with improved PFS.

Conclusions and Relevance

This phase 2 nonrandomized controlled trial found that neoadjuvant nivolumab and chemotherapy followed by response-adapted LRT is feasible and has favorable tolerability, excellent OS, and improved functional outcomes in HPV+ OPC, including among patients with high-risk disease. Moreover, addition of nivolumab may benefit high PD-L1 expressors, and sensitive dynamic biomarkers (eg, ctHPV-DNA) are useful for patient selection.

Trial Registration

ClinicalTrials.gov Identifier: NCT03107182.

A Contrast-Enhanced Tri-Modal MRI Technique for High-Performance Hypoxia Imaging of Breast Cancer

Personalized radiotherapy strategies enabled by the construction of hypoxia-guided biological target volumes (BTVs) can overcome hypoxia-induced radioresistance by delivering high-dose radiotherapy to targeted hypoxic areas of the tumor. However, the construction of hypoxia-guided BTVs is difficult owing to lack of precise visualization of hypoxic areas. This study synthesizes a hypoxia-responsive T1, T2, T2 mapping tri-modal MRI molecular nanoprobe (SPION@ND) and provides precise imaging of hypoxic tumor areas by utilizing the advantageous features of tri-modal magnetic resonance imaging (MRI). SPION@ND exhibits hypoxia-triggered dispersion-aggregation structural transformation. Dispersed SPION@ND can be used for routine clinical BTV construction using T1-contrast MRI. Conversely, aggregated SPION@ND can be used for tumor hypoxia imaging assessment using T2-contrast MRI. Moreover, by introducing T2 mapping, this work designs a novel method (adjustable threshold-based hypoxia assessment) for the precise assessment of tumor hypoxia confidence area and hypoxia level. Eventually this work successfully obtains hypoxia tumor target and accurates hypoxia tumor target, and achieves a one-stop hypoxia-guided BTV construction. Compared to the positron emission tomography-based hypoxia assessment, SPION@ND provides a new method that allows safe and convenient imaging of hypoxic tumor areas in clinical settings.

The significance of partial volume effect on the estimation of hypoxic tumour volume with [18F]FMISO PET/CT

BACKGROUND

The purpose of this study was to evaluate how a retrospective correction of the partial volume effect (PVE) in [18F]fluoromisonidazole (FMISO) PET imaging, affects the hypoxia discoverability within a gross tumour volume (GTV). This method is based on recovery coefficients (RC) and is tailored for low-contrast tracers such as FMISO. The first stage was the generation of the scanner's RC curves, using spheres with diameters from 10 to 37 mm, and the same homogeneous activity concentration, positioned in lower activity concentration background. Six sphere-to-background contrast ratios were used, from 10.0:1, down to 2.0:1, in order to investigate the dependence of RC on both the volume and the contrast ratio. The second stage was to validate the recovery-coefficient correction method in a more complex environment of non-spherical lesions of different volumes and inhomogeneous activity concentration. Finally, we applied the correction method to a clinical dataset derived from a prospective imaging trial (DRKS00003830): forty nine head and neck squamous cell carcinoma (HNSCC) cases who had undergone FMISO PET/CT scanning for the quantification of tumour hypoxia before (W0), 2 weeks (W2) and 5 weeks (W5) after the beginning of radiotherapy. Here, PVE was found to cause an underestimation of the activity in small volumes with high FMISO signal.

RESULTS

The application of the proposed correction method resulted in a statistically significant increase of both the hypoxic subvolume (171% at W0, 691% at W2 and 4.60 × 103% at W5 with p < 0.001) and the FMISO standardised uptake value (SUV) (27% at W0, 21% at W2 and by 25% at W5 with p < 0.001) within the primary GTV.

CONCLUSIONS

The proposed PVE-correction method resulted in a statistically significant increase of the hypoxic fraction (HF) with p < 0.001 and demonstrated results in better agreement with published HF data for HNSCC. To summarise, the proposed RC-based correction method can be a useful tool for a retrospective compensation against PVE.

Post-therapy emergence of an NBN reversion mutation in a patient with pancreatic acinar cell carcinoma

Pancreatic acinar cell carcinoma (PACC) is a rare form of pancreatic cancer that commonly harbors targetable alterations, including activating fusions in the MAPK pathway and loss-of-function (LOF) alterations in DNA damage response/homologous recombination DNA repair-related genes. Here, we describe a patient with PACC harboring both somatic biallelic LOF of NBN and an activating NTRK1 fusion. Upon disease progression following 13 months of treatment with folinic acid, fluorouracil, irinotecan, and oxaliplatin (FOLFIRINOX), genomic analysis of a metastatic liver biopsy revealed the emergence of a novel reversion mutation restoring the reading frame of NBN. To our knowledge, genomic reversion of NBN has not been previously reported as a resistance mechanism in any tumor type. The patient was treated with, but did not respond to, targeted treatment with a selective NTRK inhibitor. This case highlights the complex but highly actionable genomic landscape of PACC and underlines the value of genomic profiling of rare tumor types such as PACC.

Clinical Workflow of Cone Beam Computer Tomography-Based Daily Online Adaptive Radiotherapy with Offline Magnetic Resonance Guidance: The Modular Adaptive Radiotherapy System (MARS)

PURPOSE

The Ethos (Varian Medical Systems) radiotherapy device combines semi-automated anatomy detection and plan generation for cone beam computer tomography (CBCT)-based daily online adaptive radiotherapy (oART). However, CBCT offers less soft tissue contrast than magnetic resonance imaging (MRI). This work aims to present the clinical workflow of CBCT-based oART with shuttle-based offline MR guidance.

METHODS

From February to November 2023, 31 patients underwent radiotherapy on the Ethos (Varian, Palo Alto, CA, USA) system with machine learning (ML)-supported daily oART. Moreover, patients received weekly MRI in treatment position, which was utilized for daily plan adaptation, via a shuttle-based system. Initial and adapted treatment plans were generated using the Ethos treatment planning system. Patient clinical data, fractional session times (MRI + shuttle transport + positioning, adaptation, QA, RT delivery) and plan selection were assessed for all fractions in all patients.

RESULTS

In total, 737 oART fractions were applied and 118 MRIs for offline MR guidance were acquired. Primary sites of tumors were prostate (n = 16), lung (n = 7), cervix (n = 5), bladder (n = 1) and endometrium (n = 2). The treatment was completed in all patients. The median MRI acquisition time including shuttle transport and positioning to initiation of the Ethos adaptive session was 53.6 min (IQR 46.5-63.4). The median total treatment time without MRI was 30.7 min (IQR 24.7-39.2). Separately, median adaptation, plan QA and RT times were 24.3 min (IQR 18.6-32.2), 0.4 min (IQR 0.3-1,0) and 5.3 min (IQR 4.5-6.7), respectively. The adapted plan was chosen over the scheduled plan in 97.7% of cases.

CONCLUSION

This study describes the first workflow to date of a CBCT-based oART combined with a shuttle-based offline approach for MR guidance. The oART duration times reported resemble the range shown by previous publications for first clinical experiences with the Ethos system.

Hypoxia-Directed Treatment of Human Papillomavirus-Related Oropharyngeal Carcinoma

PURPOSE

Standard curative-intent chemoradiotherapy for human papillomavirus (HPV)-related oropharyngeal carcinoma results in significant toxicity. Since hypoxic tumors are radioresistant, we posited that the aerobic state of a tumor could identify patients eligible for de-escalation of chemoradiotherapy while maintaining treatment efficacy.

METHODS

We enrolled patients with HPV-related oropharyngeal carcinoma to receive de-escalated definitive chemoradiotherapy in a phase II study (ClinicalTrials.gov identifier: NCT03323463). Patients first underwent surgical removal of disease at their primary site, but not of gross disease in the neck. A baseline 18F-fluoromisonidazole positron emission tomography scan was used to measure tumor hypoxia and was repeated 1-2 weeks intratreatment. Patients with nonhypoxic tumors received 30 Gy (3 weeks) with chemotherapy, whereas those with hypoxic tumors received standard chemoradiotherapy to 70 Gy (7 weeks). The primary objective was achieving a 2-year locoregional control (LRC) of 95% with a 7% noninferiority margin.

RESULTS

One hundred fifty-eight patients with T0-2/N1-N2c were enrolled, of which 152 patients were eligible for analyses. Of these, 128 patients met criteria for 30 Gy and 24 patients received 70 Gy. The 2-year LRC was 94.7% (95% CI, 89.8 to 97.7), meeting our primary objective. With a median follow-up time of 38.3 (range, 22.1-58.4) months, the 2-year progression-free survival (PFS) and overall survival (OS) rates were 94% and 100%, respectively, for the 30-Gy cohort. The 70-Gy cohort had similar 2-year PFS and OS rates at 96% and 96%, respectively. Acute grade 3-4 adverse events were more common in 70 Gy versus 30 Gy (58.3% v 32%; P = .02). Late grade 3-4 adverse events only occurred in the 70-Gy cohort, in which 4.5% complained of late dysphagia.

CONCLUSION

Tumor hypoxia is a promising approach to direct dosing of curative-intent chemoradiotherapy for HPV-related carcinomas with preserved efficacy and substantially reduced toxicity that requires further investigation.

Reduced mouth opening in patients with head and neck cancer treated with radiation therapy: an analysis of the Clinical Registry of Dental Outcomes in Head and Neck Cancer Patients (OraRad)

OBJECTIVE

Trismus/reduced mouth opening (RMO) is a common side effect of radiotherapy (RT) for head and neck cancer (HNC). The objective was to measure RMO, identify risk factors for RMO, and determine its impact on quality of life (QOL).

STUDY DESIGN

OraRad is an observational, prospective, multicenter cohort study of patients receiving curative intent RT for HNC. Interincisal mouth opening measurements (n = 565) and patient-reported outcomes were recorded before RT and every 6 months for 2 years. Linear mixed-effects models were used to evaluate change in mouth opening and assess the relationship between trismus history and change in QOL measures.

RESULTS

Interincisal distance decreased from a mean (SE) of 45.1 (0.42) mm at baseline to 42.2 (0.44) at 6 months, with slight recovery at 18 months (43.3, 0.46 mm) but no additional improvement by 24 months. The odds of trismus (opening <35 mm) were significantly higher at 6 months (odds ratio [OR] = 2.21, 95% CI: 1.30 to 3.76) and 12 months (OR = 1.87, 95% CI: 1.08 to 3.25) compared with baseline. Females were more likely to experience trismus at baseline and during follow-up (P < .01). Patients with oral cavity cancer had the highest risk for trismus at baseline and post-RT (P < .01). RMO was associated with higher RT dose to the primary site and receiving concomitant chemotherapy (P < .01). Trismus was associated with self-reported difficulty opening the mouth and dry mouth (P < .01).

CONCLUSIONS

A decrease in mouth opening is a common treatment-related toxicity after RT, with some recovery by 18 months. Trismus has a significant impact on survivor QOL.

Genomic and epigenomic basis of breast invasive lobular carcinomas lacking CDH1 genetic alterations

CDH1 (E-cadherin) bi-allelic inactivation is the hallmark alteration of breast invasive lobular carcinoma (ILC), resulting in its discohesive phenotype. A subset of ILCs, however, lack CDH1 genetic/epigenetic inactivation, and their genetic underpinning is unknown. Through clinical targeted sequencing data reanalysis of 364 primary ILCs, we identified 25 ILCs lacking CDH1 bi-allelic genetic alterations. CDH1 promoter methylation was frequent (63%) in these cases. Targeted sequencing reanalysis revealed 3 ILCs harboring AXIN2 deleterious fusions (n = 2) or loss-of-function mutation (n = 1). Whole-genome sequencing of 3 cases lacking bi-allelic CDH1 genetic/epigenetic inactivation confirmed the AXIN2 mutation and no other cell-cell adhesion genetic alterations but revealed a new CTNND1 (p120) deleterious fusion. AXIN2 knock-out in MCF7 cells resulted in lobular-like features, including increased cellular migration and resistance to anoikis. Taken together, ILCs lacking CDH1 genetic/epigenetic alterations are driven by inactivating alterations in other cell adhesion genes (CTNND1 or AXIN2), endorsing a convergent phenotype in ILC.

Is there a role for [18F]-FMISO PET to guide dose adaptive radiotherapy in head and neck cancer? A review of the literature

Purpose

Hypoxia is a major cause of radioresistance in head and neck cancer (HNC), resulting in treatment failure and disease recurrence. 18F-fluoromisonidazole [18F]FMISO PET has been proposed as a means of localising intratumoural hypoxia in HNC so that radiotherapy can be specifically escalated in hypoxic regions. This concept may not be deliverable in routine clinical practice, however, given that [18F]FMISO PET is costly, time consuming and difficult to access. The aim of this review was to summarise clinical studies involving [18F]FMISO PET to ascertain whether it can be used to guide radiotherapy treatment in HNC.

Methods

A comprehensive literature search was conducted on PubMed and Web of Science databases. Studies investigating [18F]FMISO PET in newly diagnosed HNC patients were considered eligible for review.

Results

We found the following important results from our literature review: 1)Studies have focussed on comparing [18F]FMISO PET to other hypoxia biomarkers, but currently there is no evidence of a strong correlation between [18F]FMISO and these biomarkers.2)The results of [18F]FMISO PET imaging are not necessarily repeatable, and the location of uptake may vary during treatment.3)Tumour recurrences do not always occur within the pretreatment hypoxic volume on [18F]FMISO PET.4)Dose modification studies using [18F]FMISO PET are in a pilot phase and so far, none have demonstrated the efficacy of radiotherapy dose painting according to [18F]FMISO uptake on PET.

Conclusions

Our results suggest it is unlikely [18F]FMISO PET will be suitable for radiotherapy dose adaptation in HNC in a routine clinical setting. Part of the problem is that hypoxia is a dynamic phenomenon, and thus difficult to delineate on a single scan. Currently, it is anticipated that [18F]FMISO PET will remain useful within the research setting only.

Selective Treatment Deintensification by Reducing Radiation Dose and Omitting Concurrent Chemotherapy Based on Response to Induction Chemotherapy in Human Papillomavirus-Associated Oropharyngeal Squamous Cell Carcinoma: A Single-Arm, Phase 2 Trial (IChoice-01)

PURPOSE

To demonstrate the feasibility of deintensification regimen in the light of the response to induction chemotherapy (IC) in human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC).

METHODS AND MATERIALS

Patients with p16+ OPSCC, T1-2/N1-3M0 (excluding T1N1M0 with single and ≤3 cm lymph node) or T3-4N0-3M0 were enrolled between January 2019 and July 2021. All patients received 2 cycles of IC with docetaxel 75 mg/m2 dL and cisplatin 75 mg/m2 dL every 3 weeks. Those with major responses (≥50% decrease in both primary and lymph nodes) to IC entered the deintensification cohort (cohort D), in which intensity modulated radiation therapy alone was given to a reduced dose of 60 Gy/30 fractions. Those who failed to meet major responsesentered the concurrent chemoradiotherapy cohort (cohort C), where the dose was simultaneously integrated boosted to a standard 70 Gy/35 fractions to nonmajor response sites, concurrently with cisplatin 80 mg/m2 dL,22. Patient-reported swallow function was documented using the MD Anderson Dysphagia Inventory. The primary endpoint was 2-year progression-free survival (PFS) using Simon's 2 stage design.

RESULTS

A total of 26 of 48 (54.2%) participants met the criteria to enter cohort D and 22 of 48 (45.8%) patients entered cohort C. With a median follow-up time of 29.7 months (6.9-48.0 months), 2-year PFS and OS rates were 85.4% and 93.6%, respectively for all enrolled patients. In cohort D, 2-year PFS and OS rates were both 100%. Grade 3 and 4 IC-related toxicities included leukopenia/neutropenia occurring in 41.7% and hyponatremia in 4.2% of patients. A higher incidence of grade 3 and 4 mucositis (61.9% vs 23.1% P = .022) was observed in cohort C. Consistent decline in longitudinal MD Anderson Dysphagia Inventory scores were observed at month 3 after radiation therapy between cohorts and both were found to recover to baseline at month 12.

CONCLUSIONS

Selective radiation therapy dose reduction and concurrent chemotherapy removal based on IC response in HPV + OPSCC was feasible and promising. Further study of this strategy to balance efficacy and toxicity is warranted in a prospective controlled trial.

Recent advances in head and neck surgical oncology

In recent years, the field of head and neck oncology has witnessed a remarkable transformation with unprecedented advances that have revolutionized the management of complex tumors in this region. As an intricate subspecialty within oncology, head and neck surgical procedures demand detailed knowledge of the complex anatomy meticulous precision in surgical technique, and expertise to preserve vital functions while ensuring optimal oncological outcomes. With the relentless pursuit of improved patient outcomes, the integration of innovative technologies has significantly enhanced the surgical armamentarium. Robotics, endoscopic platforms, and image-guided navigation have revolutionized the surgical approach, enabling precise tumor resection and sparing healthy tissues. Furthermore, the application of advanced imaging modalities and molecular biomarker profiling has opened new avenues for personalized treatment strategies. From targeted therapies and immunotherapies to adaptive radiation techniques, clinicians are now equipped with an array of tailored options, ushering in a new era of personalized care for patients with head and neck malignancies. This article delves into the unfolding narratives of clinical triumphs, exploring the transformative potential of emerging therapies and the collaborative efforts propelling head and neck surgical oncology toward a future of hope and healing.

Low contralateral failure rate with unilateral proton beam radiotherapy for oropharyngeal squamous cell carcinoma: A multi-institutional prospective study from the proton collaborative group

INTRODUCTION

Unilateral radiation therapy is appropriate for select patients with oropharyngeal squamous cell carcinoma (OPSCC). The use of proton beam therapy (PBT) in the unilateral setting decreases the dose to the contralateral neck and organs at risk. This study aims to evaluate contralateral recurrences in patients who received ipsilateral PBT.

METHODS

We evaluated the Proton Collaborative Group database for patients treated with PBT for head and neck squamous cell carcinoma between the years 2015-2020 at 12 institutions. Dosimetric analysis was performed in five cases.

RESULTS

Our analysis included 41 patients that received ipsilateral PBT with a mean follow-up of 14.7 months. 37% patients (n = 15) were treated for recurrent disease, and 63% (n = 26) were treated for de novo disease. Oropharyngeal sites included tonsillar fossa (n = 30) and base of tongue (n = 11). The median dose and BED delivered were 69.96 CGE and 84 Gy, respectively. Eight (20%) patients experienced at least one grade 3 dysphagia (n = 4) or esophagitis (n = 4) toxicity. No grade ≥ 4 toxicities were reported. There was one (2.4%) failure in the contralateral neck. The 1-year locoregional control was 88.9% and the freedom from distant metastasis was 95.5% (n = 2). The dosimetric analysis demonstrated similar ipsilateral level II cervical nodal region doses, whereas contralateral doses were higher with photon plans, mean: 15.5 Gy and 0.7CGE, D5%: 25.1 Gy and 6.6CGE.

CONCLUSIONS

Our series is the first to report outcomes for patients with OPSCC receiving unilateral PBT. The contralateral neck failure rate was excellent and comparable to failure rates with photon irradiation.

Auto-segmentation of neck nodal metastases using self-distilled masked image transformer on longitudinal MR images

Objectives

Auto-segmentation promises greater speed and lower inter-reader variability than manual segmentations in radiation oncology clinical practice. This study aims to implement and evaluate the accuracy of the auto-segmentation algorithm, "Masked Image modeling using the vision Transformers (SMIT)," for neck nodal metastases on longitudinal T2-weighted (T2w) MR images in oropharyngeal squamous cell carcinoma (OPSCC) patients.

Methods

This prospective clinical trial study included 123 human papillomaviruses (HPV-positive [+]) related OSPCC patients who received concurrent chemoradiotherapy. T2w MR images were acquired on 3 T at pre-treatment (Tx), week 0, and intra-Tx weeks (1-3). Manual delineations of metastatic neck nodes from 123 OPSCC patients were used for the SMIT auto-segmentation, and total tumor volumes were calculated. Standard statistical analyses compared contour volumes from SMIT vs manual segmentation (Wilcoxon signed-rank test [WSRT]), and Spearman's rank correlation coefficients (ρ) were computed. Segmentation accuracy was evaluated on the test data set using the dice similarity coefficient (DSC) metric value. P-values <0.05 were considered significant.

Results

No significant difference in manual and SMIT delineated tumor volume at pre-Tx (8.68 ± 7.15 vs 8.38 ± 7.01 cm3, P = 0.26 [WSRT]), and the Bland-Altman method established the limits of agreement as -1.71 to 2.31 cm3, with a mean difference of 0.30 cm3. SMIT model and manually delineated tumor volume estimates were highly correlated (ρ = 0.84-0.96, P < 0.001). The mean DSC metric values were 0.86, 0.85, 0.77, and 0.79 at the pre-Tx and intra-Tx weeks (1-3), respectively.

Conclusions

The SMIT algorithm provides sufficient segmentation accuracy for oncological applications in HPV+ OPSCC.

Advances in knowledge

First evaluation of auto-segmentation with SMIT using longitudinal T2w MRI in HPV+ OPSCC.

Genomic Tumor Correlates of Clinical Outcomes Following Organ-Sparing Chemoradiation Therapy for Bladder Cancer

PURPOSE

There is an urgent need for biomarkers of radiation response in organ-sparing therapies. Bladder preservation with trimodality therapy (TMT), consisting of transurethral tumor resection followed by chemoradiation, is an alternative to radical cystectomy for muscle-invasive bladder cancer (MIBC), but molecular determinants of response are poorly understood.

EXPERIMENTAL DESIGN

We characterized genomic and transcriptomic features correlated with long-term response in a single institution cohort of patients with MIBC homogeneously treated with TMT. Pretreatment tumors from 76 patients with MIBC underwent whole-exome sequencing; 67 underwent matched transcriptomic profiling. Molecular features were correlated with clinical outcomes including modified bladder-intact event-free survival (mBI-EFS), a composite endpoint that reflects long-term cancer control with bladder preservation.

RESULTS

With a median follow-up of 74.6 months in alive patients, 37 patients had favorable long-term response to TMT while 39 had unfavorable long-term response. Tumor mutational burden was not associated with outcomes after TMT. DNA damage response gene alterations were associated with improved locoregional control and mBI-EFS. Of these alterations, somatic ERCC2 mutations stood out as significantly associated with favorable long-term outcomes; patients with ERCC2 mutations had significantly improved mBI-EFS [HR, 0.15; 95% confidence interval (CI), 0.06-0.37; P = 0.030] and improved BI-EFS, an endpoint that includes all-cause mortality (HR, 0.33; 95% CI, 0.15-0.68; P = 0.044). ERCC2 mutant bladder cancer cell lines were significantly more sensitive to concurrent cisplatin and radiation treatment in vitro than isogenic ERCC2 wild-type cells.

CONCLUSIONS

Our data identify ERCC2 mutation as a candidate biomarker associated with sensitivity and long-term response to chemoradiation in MIBC. These findings warrant validation in independent cohorts.

Virtual Tumor Board to Foster Interinstitutional Head and Neck Cancer Subspecialty Care

This cross-sectional study evaluates the concordance on treatment and diagnostic recommendations between clinicians at 2 collaborating health systems.

Genomic Profiling Reveals Germline Predisposition and Homologous Recombination Deficiency in Pancreatic Acinar Cell Carcinoma

PURPOSE

To determine the genetic predisposition underlying pancreatic acinar cell carcinoma (PACC) and characterize its genomic features.

METHODS

Both somatic and germline analyses were performed using an Food and Drug Administration-authorized matched tumor/normal sequencing assay on a clinical cohort of 28,780 patients with cancer, 49 of whom were diagnosed with PACC. For a subset of PACCs, whole-genome sequencing (WGS; n = 12) and RNA sequencing (n = 6) were performed.

RESULTS

Eighteen of 49 (36.7%) PACCs harbored germline pathogenic variants in homologous recombination (HR) and DNA damage response (DDR) genes, including BRCA1 (n = 1), BRCA2 (n = 12), PALB2 (n = 2), ATM (n = 2), and CHEK2 (n = 1). Thirty-one PACCs displayed pure, and 18 PACCs harbored mixed acinar cell histology. Fifteen of 31 (48%) pure PACCs harbored a germline pathogenic variant affecting HR-/DDR-related genes. BRCA2 germline pathogenic variants (11 of 31, 35%) were significantly more frequent in pure PACCs than in pancreatic adenocarcinoma (86 of 2,739, 3.1%; P < .001), high-grade serous ovarian carcinoma (67 of 1,318, 5.1%; P < .001), prostate cancer (116 of 3,401, 3.4%; P < .001), and breast cancer (79 of 3,196, 2.5%; P < .001). Genomic features of HR deficiency (HRD) were detected in 7 of 12 PACCs undergoing WGS, including 100% (n = 6) of PACCs with germline HR-related pathogenic mutations and 1 of 6 PACCs lacking known pathogenic alterations in HR-related genes. Exploratory analyses revealed that in PACCs, the repertoire of somatic driver genetic alterations and the load of neoantigens with high binding affinity varied according to the presence of germline pathogenic alterations affecting HR-/DDR-related genes and/or HRD.

CONCLUSION

In a large pan-cancer cohort, PACC was identified as the cancer type with the highest prevalence of both BRCA2 germline pathogenic variants and genomic features of HRD, suggesting that PACC should be considered as part of the spectrum of BRCA-related malignancies.

A Quantitative Multiparametric MRI Analysis Platform for Estimation of Robust Imaging Biomarkers in Clinical Oncology

There is a need to develop user-friendly imaging tools estimating robust quantitative biomarkers (QIBs) from multiparametric (mp)MRI for clinical applications in oncology. Quantitative metrics derived from (mp)MRI can monitor and predict early responses to treatment, often prior to anatomical changes. We have developed a vendor-agnostic, flexible, and user-friendly MATLAB-based toolkit, MRI-Quantitative Analysis and Multiparametric Evaluation Routines ("MRI-QAMPER", current release v3.0), for the estimation of quantitative metrics from dynamic contrast-enhanced (DCE) and multi-b value diffusion-weighted (DW) MR and MR relaxometry. MRI-QAMPER's functionality includes generating numerical parametric maps from these methods reflecting tumor permeability, cellularity, and tissue morphology. MRI-QAMPER routines were validated using digital reference objects (DROs) for DCE and DW MRI, serving as initial approval stages in the National Cancer Institute Quantitative Imaging Network (NCI/QIN) software benchmark. MRI-QAMPER has participated in DCE and DW MRI Collaborative Challenge Projects (CCPs), which are key technical stages in the NCI/QIN benchmark. In a DCE CCP, QAMPER presented the best repeatability coefficient (RC = 0.56) across test-retest brain metastasis data, out of ten participating DCE software packages. In a DW CCP, QAMPER ranked among the top five (out of fourteen) tools with the highest area under the curve (AUC) for prostate cancer detection. This platform can seamlessly process mpMRI data from brain, head and neck, thyroid, prostate, pancreas, and bladder cancer. MRI-QAMPER prospectively analyzes dose de-escalation trial data for oropharyngeal cancer, which has earned it advanced NCI/QIN approval for expanded usage and applications in wider clinical trials.

Adaptive FDG-PET/CT guided dose escalation in head and neck squamous cell carcinoma: Late toxicity and oncologic outcomes (The ADMIRE study)

Purpose

To report on the late toxicity and local control (LC) of head and neck cancer patients treated with adaptive FDG-PET/CT response-guided radiotherapy (ADMIRE) with dose escalation (NCT03376386).

Materials and methods

Between December 2017 and April 2019, 20 patients with stage II-IV squamous cell carcinoma of the larynx, hypopharynx or oropharynx were treated within the ADMIRE study where FDG-PET/CT response-guided (Week 2&4) dose escalation was applied (total dose 70-78 Gy). Cisplatin or cetuximab was added to radiotherapy in case of T3-4 and/or N2c disease. To compare the LC and late toxicity of the study population, we used an external control group (n = 67) consisting of all eligible patients for the study (but not participated). These patients were treated in our institution during the same period with the current standard of 70 Gy radiotherapy. To reduce the effect of confounding, logistic regression analyses was done using stabilized inverse probability of treatment weighting (SIPTW).

Results

After median follow-up of 40 and 43 months for the ADMIRE and control groups, the 3-year LC-rates were 74% and 78%, respectively (adjusted HR after SIPTW 0.80, 95 %CI 0.25-2.52, p = 0.70). The incidences of any late G3 toxicity were 35% and 18%, respectively. The adjusted OR for any late G3 toxicity was 5.09 (95 %CI 1.64-15.8, p = 0.005), for any late G ≥ 2 toxicity was 3.67 (95 %CI 1.2-11.7, p = 0.02), for persistent laryngeal edema was 10.95 (95% CI 2.71-44.29, p = 0.001), for persistent mucosal ulcers was 4.67 (95% CI 1.23-17.7, p = 0.023), and for late G3 radionecrosis was 15.69 (95 %CI 2.43-101.39, p = 0.004).

Conclusion

Given the comparable LC rates with increased late toxicity in the ADMIRE group, selection criteria for future adaptive dose escalation trials (preferably randomized) need to be refined to include only patients at higher risk of local failure and/or lower risk of severe late toxicity.

Absolute oxygen-guided radiation therapy improves tumor control in three preclinical tumor models

Background

Clinical attempts to find benefit from specifically targeting and boosting resistant hypoxic tumor subvolumes have been promising but inconclusive. While a first preclinical murine tumor type showed significant improved control with hypoxic tumor boosts, a more thorough investigation of efficacy from boosting hypoxic subvolumes defined by electron paramagnetic resonance oxygen imaging (EPROI) is necessary. The present study confirms improved hypoxic tumor control results in three different tumor types using a clonogenic assay and explores potential confounding experimental conditions.

Materials and methods

Three murine tumor models were used for multi-modal imaging and radiotherapy: MCa-4 mammary adenocarcinomas, SCC7 squamous cell carcinomas, and FSa fibrosarcomas. Registered T2-weighted MRI tumor boundaries, hypoxia defined by EPROI as pO2 ≤ 10 mmHg, and X-RAD 225Cx CT boost boundaries were obtained for all animals. 13 Gy boosts were directed to hypoxic or equal-integral-volume oxygenated tumor regions and monitored for regrowth. Kaplan-Meier survival analysis was used to assess local tumor control probability (LTCP). The Cox proportional hazards model was used to assess the hazard ratio of tumor progression of Hypoxic Boost vs. Oxygenated Boost for each tumor type controlling for experimental confounding variables such as EPROI radiofrequency, tumor volume, hypoxic fraction, and delay between imaging and radiation treatment.

Results

An overall significant increase in LTCP from Hypoxia Boost vs. Oxygenated Boost treatments was observed in the full group of three tumor types (p < 0.0001). The effects of tumor volume and hypoxic fraction on LTCP were dependent on tumor type. The delay between imaging and boost treatments did not have a significant effect on LTCP for all tumor types.

Conclusion

This study confirms that EPROI locates resistant tumor hypoxic regions for radiation boost, increasing clonogenic LTCP, with potential enhanced therapeutic index in three tumor types. Preclinical absolute EPROI may provide correction for clinical hypoxia images using additional clinical physiologic MRI.

Clinical-genomic determinants of immune checkpoint blockade response in head and neck squamous cell carcinoma

BACKGROUNDRecurrent and/or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) is generally an incurable disease, with patients experiencing median survival of under 10 months and significant morbidity. While immune checkpoint blockade (ICB) drugs are effective in approximately 20% of patients, the remaining experience limited clinical benefit and are exposed to potential adverse effects and financial costs. Clinically approved biomarkers, such as tumor mutational burden (TMB), have a modest predictive value in HNSCC.METHODSWe analyzed clinical and genomic features, generated using whole-exome sequencing, in 133 ICB-treated patients with R/M HNSCC, of whom 69 had virus-associated and 64 had non-virus-associated tumors.RESULTSHierarchical clustering of genomic data revealed 6 molecular subtypes characterized by a wide range of objective response rates and survival after ICB therapy. The prognostic importance of these 6 subtypes was validated in an external cohort. A random forest-based predictive model, using several clinical and genomic features, predicted progression-free survival (PFS), overall survival (OS), and response with greater accuracy than did a model based on TMB alone. Recursive partitioning analysis identified 3 features (systemic inflammatory response index, TMB, and smoking signature) that classified patients into risk groups with accurate discrimination of PFS and OS.CONCLUSIONThese findings shed light on the immunogenomic characteristics of HNSCC tumors that drive differential responses to ICB and identify a clinical-genomic classifier that outperformed the current clinically approved biomarker of TMB. This validated predictive tool may help with clinical risk stratification in patients with R/M HNSCC for whom ICB is being considered.FUNDINGFundación Alfonso Martín Escudero, NIH R01 DE027738, US Department of Defense CA210784, The Geoffrey Beene Cancer Research Center, The MSKCC Population Science Research Program, the Jayme Flowers Fund, the Sebastian Nativo Fund, and the NIH/NCI Cancer Center Support Grant P30 CA008748.

Initial Feasibility and Acute Toxicity Outcomes From a Phase 2 Trial of 18F-Fluorodeoxyglucose Positron Emission Tomography Response-Based De-escalated Definitive Chemoradiotherapy for p16+ Oropharynx Cancer: A Planned Interim Analysis

PURPOSE

18F-Fluorodeoxyglucose positron emission tomography (FDG-PET) parameters are prognostic of oncologic outcomes in human papillomavirus-associated oropharyngeal squamous cell carcinoma (OPSCC). We used FDG-PET imaging biomarkers to select patients for de-escalated chemoradiotherapy (CRT), hypothesizing that acute toxicity will be improved with de-escalation.

METHODS AND MATERIALS

This is a planned interim initial feasibility and acute toxicity report from a phase 2, prospective, nonrandomized study, which enrolled patients with stage I-II p16+ OPSCC. All patients started definitive CRT to 70 Gy in 35 fractions, and those who met de-escalation criteria on midtreatment FDG-PET at fraction 10 completed treatment at 54 Gy in 27 fractions. We report the acute toxicity and patient-reported outcomes for 59 patients with a minimum follow-up of 3 months.

RESULTS

There were no statistically significant differences between baseline patient characteristics in the standard and de-escalated cohorts. There were 28 of 59 (47.5%) patients who met FDG-PET de-escalation criteria and collectively received 20% to 30% less dose to critical organs at risk known to affect toxicity. At 3 months posttreatment, patients who received de-escalated CRT lost significantly less weight (median, 5.8% vs 13.0%; P < .001), had significantly less change from baseline in penetration-aspiration scale score (median, 0 vs 1; P = .018), and had significantly fewer aspiration events on repeat swallow study (8.0% vs 33.3%, P = .037) compared with patients receiving standard CRT.

CONCLUSIONS

Approximately half of patients with early-stage p16+ OPSCC are selected for de-escalation of definitive CRT using midtreatment FDG-PET biomarkers, which resulted in significantly improved rates of observed acute toxicity. Further follow-up is ongoing and will be required to determine whether this de-escalation approach preserves the favorable oncologic outcomes for patients with p16+ OPSCC before adoption.

[Research progress on the treatment improvement of HPV-associated oropharyngeal cancer]

The number of new cases of oropharyngeal cancer is increasing year by year among the world, and HPV infection is one of the risk factors for this malignant tumor. Compared with HPV-negative oropharyngeal cancer, HPV-positive patients are more sensitive to radiotherapy and have a better prognosis, but there is no accepted treatment for HPV-positive patients. Reducing treatment intensity moderately and exploring the best option to minimize side effects of treatment are urgent issues to be addressed. This article reviews the research progress on the treatment improvement of HPV-associated oropharyngeal cancer in recent years.

Machine learning identifies multi-parametric functional PET/MR imaging cluster to predict radiation resistance in preclinical head and neck cancer models

PURPOSE

Tumor hypoxia and other microenvironmental factors are key determinants of treatment resistance. Hypoxia positron emission tomography (PET) and functional magnetic resonance imaging (MRI) are established prognostic imaging modalities to identify radiation resistance in head-and-neck cancer (HNC). The aim of this preclinical study was to develop a multi-parametric imaging parameter specifically for focal radiotherapy (RT) dose escalation using HNC xenografts of different radiation sensitivities.

METHODS

A total of eight human HNC xenograft models were implanted into 68 immunodeficient mice. Combined PET/MRI using dynamic [18F]-fluoromisonidazole (FMISO) hypoxia PET, diffusion-weighted (DW), and dynamic contrast-enhanced MRI was carried out before and after fractionated RT (10 × 2 Gy). Imaging data were analyzed on voxel-basis using principal component (PC) analysis for dynamic data and apparent diffusion coefficients (ADCs) for DW-MRI. A data- and hypothesis-driven machine learning model was trained to identify clusters of high-risk subvolumes (HRSs) from multi-dimensional (1-5D) pre-clinical imaging data before and after RT. The stratification potential of each 1D to 5D model with respect to radiation sensitivity was evaluated using Cohen's d-score and compared to classical features such as mean/peak/maximum standardized uptake values (SUVmean/peak/max) and tumor-to-muscle-ratios (TMRpeak/max) as well as minimum/valley/maximum/mean ADC.

RESULTS

Complete 5D imaging data were available for 42 animals. The final preclinical model for HRS identification at baseline yielding the highest stratification potential was defined in 3D imaging space based on ADC and two FMISO PCs ([Formula: see text]). In 1D imaging space, only clusters of ADC revealed significant stratification potential ([Formula: see text]). Among all classical features, only ADCvalley showed significant correlation to radiation resistance ([Formula: see text]). After 2 weeks of RT, FMISO_c1 showed significant correlation to radiation resistance ([Formula: see text]).

CONCLUSION

A quantitative imaging metric was described in a preclinical study indicating that radiation-resistant subvolumes in HNC may be detected by clusters of ADC and FMISO using combined PET/MRI which are potential targets for future functional image-guided RT dose-painting approaches and require clinical validation.

De-escalated radiation for human papillomavirus virus-related oropharyngeal cancer: evolving paradigms and future strategies

The incidence of human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma has increased dramatically in recent years reaching epidemic-like proportions. Data has emerged not only showing that these cancers are a unique entity with distinct molecular characteristics but that they also have a significantly improved prognosis as a result of their exquisite radiosensitivity compared to their HPV-negative counterparts. This, it has been increasingly suggested that these tumors can be targeted with de-escalated approaches using reduced doses of radiation. The overriding goal of de-escalation is to maintain the high cure and survival rates associated with traditional approaches while reducing the incidence of both short- and long-term toxicity. Although the exact reason for the improved radiosensitivity of HPV-positive oropharyngeal carcinoma is unclear, prospective studies have now been published demonstrating that de-escalated radiation can successfully maintain the high rates of cure and preserve quality of life for appropriately selected patients with this disease. However, these studies have been complicated by such factors as the relatively limited sample sizes, as well as the variability in treatment, inclusion criteria, and follow-up. As the data continues to mature on de-escalation, it is unquestionable that treatment paradigms for this disease will evolve. The ongoing quest to define a standard regimen comprises the subject of this review.

The Utility of Interim Positron Emission Tomography Imaging to Inform Adaptive Radiotherapy for Head and Neck Squamous Cell Carcinoma

ABSTRACT

In this article, as part of this special issue on biomarkers of early response, we review the current evidence to support the use of positron emission tomography (PET) imaging during chemoradiation therapy to inform biologically adaptive radiotherapy for head and neck squamous cell carcinoma. We review literature covering this topic spanning nearly 3 decades, including the use of various radiotracers and discoveries of novel predictive PET biomarkers. Through understanding how observational trials have informed current interventional clinical trials, we hope that this review will encourage researchers and clinicians to incorporate PET response criteria in new trial designs to advance biologically optimized radiotherapy.

Hypoxia-Targeted Dose Painting in Radiotherapy

Hypoxia (oxygen deprivation) occurs in most solid malignancies, albeit with considerable heterogeneity. Hypoxia is associated with an aggressive cancer phenotype by promotion of genomic instability, evasion of anti-cancer therapies including radiotherapy and enhancement of metastatic risk. Therefore, hypoxia results in poor cancer outcomes. Targeting hypoxia to improve cancer outcomes is an attractive therapeutic strategy. Hypoxia-targeted dose painting escalates radiotherapy dose to hypoxic sub-volumes, as quantified and spatially mapped using hypoxia imaging. This therapeutic approach could overcome hypoxia-induced radioresistance and improve patient outcomes without the need for hypoxia-targeted drugs. This article will review the premise and underpinning evidence for personalized hypoxia-targeted dose painting. It will present data on relevant hypoxia imaging biomarkers, highlight the challenges and potential benefit of this approach and provide recommendations for future research priorities in this field. Personalized hypoxia-based radiotherapy de-escalation strategies will also be addressed.

Lessons and Opportunities for Biomarker-Driven Radiation Personalization in Head and Neck Cancer

Head and neck cancer is notoriously challenging to treat in part because it constitutes an anatomically and biologically diverse group of cancers with heterogeneous prognoses. While treatment can be associated with significant late toxicities, recurrence is often difficult to salvage with poor survival rates and functional morbidity.^1,2 Thus, achieving tumor control and cure at the initial diagnosis is the highest priority. Given the differing outcome expectations (even within a specific sub-site like oropharyngeal carcinoma), there has been growing interest in personalizing treatment: de-escalation in selected cancers to decrease the risk of late toxicity without compromising oncologic outcomes, and intensification for more aggressive cancers to improve oncologic outcomes without causing undue toxicity. This risk stratification is increasingly accomplished using biomarkers, which can represent molecular, clinicopathologic, and/or radiologic data. In this review, we will focus on biomarker-driven radiotherapy dose personalization with emphasis on oropharyngeal and nasopharyngeal carcinoma. This radiation personalization is largely performed on the population level by identifying patients with good prognosis via traditional clinicopathologic factors, although there are emerging studies supporting inter-tumor and intra-tumor level personalization via imaging and molecular biomarkers.