Significance of Negative Posttreatment 18-FDG PET/CT Imaging in Patients With p16/HPV-Positive Oropharyngeal Cancer

Follow-up for human papillomavirus-related oropharynx cancer concentrated on unequal symptom change (FOCUS): Prospective patient-reported outcome collection

BACKGROUND

Post-treatment surveillance recommendations for oropharyngeal cancer do not vary with p16 status despite the differences in outcomes. The optimal algorithm personalizing follow-up for these patients remains undefined. Here, we evaluate the feasibility and utility of incorporating electronic patient-reported outcomes (ePROs) and circulating tumor DNA (ctDNA) into routine surveillance for patients treated for p16+ oropharynx cancer.

METHODS

A prospective registry was developed in which ePROs and ctDNA were incorporated into routine surveillance among patients with oropharynx cancer. ePROs were emailed monthly for 1 year and blood HPV ctDNA testing was performed every 3-6 months. The primary objective was to assess patient compliance with ePRO-based surveillance with adequate compliance defined as ≥85% of patients completing monthly ePROs. Sensitivity, specificity, and positive/negative predictive values to detect recurrence were calculated for ePROs, HPV ctDNA, or the combination.

RESULTS

Of 122 patients who initially expressed interest, 76 completed the electronic consent process and 44/76 (58%) were compliant with monthly surveys over 1 year; thus adequate compliance was not achieved. Technical difficulties associated with ePRO receipt through email largely limited participation. Provider feedback was significantly associated with heightened ePRO compliance. One hundred and six patients had ctDNA testing with a mean number of three tests per patient. Sensitivity to detect recurrence was 75% for the combination of ePROs and ctDNA.

CONCLUSION

Despite lower than anticipated compliance with ePROs, our findings show promise for incorporation of HPV ctDNA into surveillance paradigms for HPV-related oropharynx cancer with suggestions of methods to optimize ePRO formats for personalized surveillance.

Cost-Effectiveness Analysis of PET-CT Surveillance After Treatment of Human Papillomavirus-Positive Oropharyngeal Cancer

OBJECTIVE

To determine the cost-effectiveness of surveillance imaging with PET/CT scan among patients with human papillomavirus-positive oropharyngeal squamous cell carcinoma.

STUDY DESIGN

Cost-effectiveness analysis.

SETTING

Oncologic care centers in the United States with head and neck oncologic surgeons and physicians.

METHODS

We compared the cost-effectiveness of 2 posttreatment surveillance strategies: clinical surveillance with the addition of PET/CT scan versus clinical surveillance alone in human papillomavirus-positive oropharyngeal squamous cell carcinoma patients. We constructed a Markov decision model which was analyzed from a third-party payer's perspective using 1-year Markov cycles and a 30-year time horizon. Values for transition probabilities, costs, health care utilities, and their studied ranges were derived from the literature.

RESULTS

The incremental cost-effectiveness ratio for PET/CT with clinical surveillance versus clinical surveillance alone was $89,850 per quality-adjusted life year gained. Flexible fiberoptic scope exams during clinical surveillance would have to be over 51% sensitive or PET/CT scan cost would have to exceed $1678 for clinical surveillance alone to be more cost-effective. The willingness-to-pay threshold at which imaging surveillance was equally cost-effective to clinical surveillance was approximately $80,000/QALY.

CONCLUSION

Despite lower recurrence rates of human papillomavirus-positive oropharyngeal cancer, a single PET/CT scan within 6 months after primary treatment remains a cost-effective tool for routine surveillance when its cost does not exceed $1678. The cost-effectiveness of this strategy is also dependent on the clinical surveillance sensitivity (flexible fiberoptic pharyngoscopy), and willingness-to-pay thresholds which vary by country.

Circulating Tumor HPV DNA for Surveillance of HPV-Positive Oropharyngeal Squamous Cell Carcinoma: A Narrative Review

Importance

Human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma has an overall favorable prognosis, yet a subset of patients will experience devastating disease recurrence. Current surveillance standards for detection of recurrent disease are imperfect. There is growing interest in improving detection of recurrent disease through the use of plasma-based assays able to detect circulating tumor HPV DNA.

Observations

Although most circulating tumor HPV DNA assays remain in the research domain, the circulating tumor tissue-modified viral HPV DNA assay became commercially available in the United States in early 2020 and has been increasingly used in the clinical setting. With the rapidly increasing incidence of HPV-positive oropharyngeal squamous cell carcinoma and concomitant expansion of biomarker capabilities for this disease, it is critical to reexamine current posttreatment surveillance practices and to determine whether emerging technologies may be used to improve outcomes for a growing survivor population. However, caution is advised; it is not yet known whether biomarker-based surveillance is truly beneficial, and as is true with any intervention, it has the capacity to cause harm.

Conclusions and Relevance

Using Margaret Pepe's classic 5 phases of biomarker development for early detection of cancer as a framework, this article reviews the current state of knowledge, highlights existing knowledge gaps, and suggests research that should be prioritized to understand the association between biomarker-based surveillance and patient outcomes. Specific attention is paid to the commercially available tumor tissue-modified viral HPV DNA assay, given its increasing clinical use. This review may serve as a road map for future research and a guide for clinicians considering its adoption in practice. Enrollment of patients into clinical trials incorporating biomarker-based surveillance should be prioritized.

Post-treatment PET/CT for p16-positive oropharynx cancer treated with definitive proton therapy

Objectives

Given emerging data suggesting that uncertainty in the relative biologic effectiveness at the distal end of the Bragg peak results in increased mucosal injury in patients with oropharynx cancer receiving adjuvant proton therapy, we evaluated the results of post-treatment positron emission tomography-computed tomography (PET/CT) in patients with p16-positive oropharynx cancer (p16+OPC) treated with definitive intensity-modulated proton therapy (IMPT).

Material and Methods

A retrospective cohort study of patients with p16+OPC treated with definitive IMPT between 2016 and 2022 was performed at a single institution. Patients with PET/CT scans within 6 months following completion of IMPT were included in the study. Positive post-treatment scans were defined by a maximum standard uptake values (SUVmax) >4.0 or a <65% reduction in SUVmax in either the primary tumor or lymph node. The Fisher's exact test was used to evaluate factors associated with positive post-treatment PET/ CT values.

Results

Sixty-two patients were included for analysis. Median follow-up was 21 months (range: 3-71 months) with a median time to post-treatment PET/CT of 3 months (range: 2-6 months). Median post-treatment SUVmax of the primary disease and nodal disease was 0 (mean: 0.8, range: 0-7.7) and 0 (mean: 0.7, range: 0-9.5), respectively. Median post-treatment percent reduction in SUVmax for the primary site and lymph node was 100% (mean: 94%, range: 31.3-100%) and 100% (mean: 89%, range: 23-100%), respectively. Eleven patients had a positive post-treatment PET/CT with one biopsy-proven recurrence. Negative and positive predictive values (NPV and PPV) were 98% and 9.1%, respectively. There were no factors associated with positive post-treatment PET/CT.

Conclusion

Similar to patients treated with photon-based radiation therapy, post-treatment PET/CT has a high NPV for patients with p16+OPC treated with definitive proton therapy and should be used to guide patient management. Additional patients and more events are needed to confirm the PPV of a post-treatment PET/CT in this favorable patient cohort.

Accuracy of Response Assessment FDG PET-CT Post (Chemo)Radiotherapy in HPV Negative Oropharynx Squamous Cell Carcinoma

Background: Data on the accuracy of response assessment 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography-computed tomography (PET-CT) following (chemo)radiotherapy in patients with oropharynx squamous cell carcinoma (OPSCC) is predominantly based on HPV-positive disease. There is a paucity of data for HPV-negative disease, which has a less favourable prognosis. Methods: 96 patients treated with (chemo)radiotherapy for HPV-negative OPSCC with baseline and response assessment FDG PET-CT between 2013−2020, were analysed. PET-CT response was classified as negative, equivocal, or positive based on qualitative reporting. PET-CT response categories were analysed with reference to clinicopathological outcomes. Test characteristics were evaluated, comparing negative results to equivocal and positive results together. Post-test probabilities were calculated separately for positive and equivocal or negative results. Results: Median follow-up was 26 months. The negative predictive value of a negative scan was 93.7 and 93.2%, respectively, for primary tumour and nodal disease. For a negative scan, the post-test probability was 0.06 for primary and 0.07 for nodal disease. The post-test probability of an equivocal scan was 0.51 and 0.72 for primary and lymph node, respectively. The post-test probability of a positive scan approached 1. For patients with/without a negative scan, two-year overall survival and progression-free survival were 83% versus 30% and 79% versus 17% (p < 0.001), respectively. Conclusion: The NPV of a negative response assessment PET-CT in HPV-negative OPSCC is high, supporting a strategy of clinical monitoring. Contrasting with the published literature for HPV-positive OPSCC, an equivocal response scan was associated with a moderate rate of residual disease.

Qualitative and quantitative methods in post-chemoradiation PET for head and neck cancer

OBJECTIVE

The aim of this study was to determine whether quantitative methods could aid in the evaluation of post-treatment head and neck scans, particularly taking human papillomavirus status into account.

METHODS

Clinical readings of positron emission tomography/computed tomography scans as well as standardized uptake value (SUV)max (and other metrics) of nodes visible on PET conducted on a total of 172 patients with head and neck squamous cell cancer were examined. Locoregional recurrence at 2 years was assessed. In total 88 of these patients had close enough follow-up to determine whether individual nodes were positive or negative, and 233 nodes on these patients were compared to surgical pathology notes or follow-up (if no path was available).

RESULTS

General negative predictive value (NPV) of complete response was 93% and an equivocal response was 89%; focusing on nodal recurrence, NPV was found to be 97% and positive predictive value (PPV) 46% if equivocal reads were treated as negative and NPV 98% and PPV 16% if equivocal reads were treated as positive. Using SUVmax of the hottest node with a cutoff of 3.4 gave NPV 97% and PPV 26%; a direct re-read (using 2 observers) gave NPV 98% and PPV 32% if equivocal reads were treated as negative, and NPV 99% and PPV 18% if equivocal reads were treated as positive. Using other first-order radiomics data such as SD and skewness did not improve this.

CONCLUSIONS

Quantitative data such as SUVmax does not show additional value over qualitative evaluation of response to chemoradiation in head and neck tumors.

Advances in Imaging for HPV-Related Oropharyngeal Cancer: Applications to Radiation Oncology

While there has been an overall decline of tobacco and alcohol-related head and neck cancer in recent decades, there has been an increased incidence of HPV-associated oropharyngeal cancer (OPC). Recent research studies and clinical trials have revealed that the cancer biology and clinical progression of HPV-positive OPC is unique relative to its HPV-negative counterparts. HPV-positive OPC is associated with higher rates of disease control following definitive treatment when compared to HPV-negative OPC. Thus, these conditions should be considered unique diseases with regards to treatment strategies and survival. In order to sufficiently characterize HPV-positive OPC and guide treatment strategies, there has been a considerable effort to diagnose, prognose, and track the treatment response of HPV-associated OPC through advanced imaging research. Furthermore, HPV-positive OPC patients are prime candidates for radiation de-escalation protocols, which will ideally reduce toxicities associated with radiation therapy and has prompted additional imaging research to detect radiation-induced changes in organs at risk. This manuscript reviews the various imaging modalities and current strategies for tackling these challenges as well as provides commentary on the potential successes and suggested improvements for the optimal treatment of these tumors.

Systematic Review and Meta-Analysis of Post-Treatment PET/CT in HPV-Associated Oropharyngeal Cancer

OBJECTIVE

To perform a systematic review with meta-analysis to investigate the utility of post-treatment PET/CT specifically in HPV-associated oropharyngeal squamous cell carcinoma following curative intent treatment.

METHODS

Random-effects meta-analysis was used to pool data from 7 observational studies (2013-2019) obtained from a database search of PubMed, Web of Science, and EMBASE using an a priori protocol with dual independent evaluation for inclusion, risk of bias assessment for acceptable methodology, and extraction of data for analysis. PET/CT results, treatment failure, imaging and interventions subsequent to PET/CT findings, and efficacy of salvage therapy were extracted.

RESULTS

Of the 907 post-treatment scans, PET/CT results were largely negative (76.2%; 95% CI, 63.4-85.6) and least often positive (11.3%; 95% CI, 8.8-14.4). PET/CT results were equivocal for 22.5% (95% CI, 12.5-36.9) and equivocal/positive for 34.2% of patients (95% CI, 25.1-44.5). Patients with an initial positive scan had the highest treatment failure rates (43.1%; 95% CI, 21.4-67.7) and those with an initial negative scan had the lowest rates (7.4%; 95% CI, 5.7-9.7). The equivocal and equivocal/positive scans had intermediate prevalence of 16.5% (95% CI, 9.4-27.6) and 16.7% (95% CI, 9.1-28.7), respectively.

CONCLUSION

The low treatment failure rate following a negative PET/CT scan is reassuring, but the data are consistent with treatment failure rates up to 9.7% suggesting follow-up of these patients is prudent. Additionally, the low positive predictive value for treatment failure observed alludes to use of post-treatment PET/CT in HPV-associated disease frequently leading to unnecessary subsequent imaging and intervention.

Patient Burden with Current Surveillance Paradigm and Factors Associated with Interest in Altered Surveillance for Early Stage HPV-Related Oropharyngeal Cancer

INTRODUCTION

Optimal surveillance paradigms for survivors of early stage human papillomavirus (HPV)-related oropharyngeal cancer are not well defined. This study aimed to characterize patient interest in and factors associated with an altered surveillance paradigm.

MATERIALS AND METHODS

We surveyed patients with Stage I or II HPV-related oropharyngeal cancer treated at a tertiary care institution from 2016 to 2019. Primary outcomes were descriptive assessment of patient knowledge, interest in altered surveillance, burdens of in-person appointments, and priorities for surveillance visits. Ordinal regression was used to identify correlates of interest in altered surveillance.

RESULTS

Sixty-seven patients completed surveys from February to April 2020 at a median of 21 months since completing definitive treatment. A majority (61%) of patients were interested in a surveillance approach that decreased in-person clinic visits. Patients who self-identified as medical maximizers, had higher worry of cancer recurrence, or were in long-term relationships were less likely to be interested. Patients reported significant burdens associated with surveillance visits, including driving distance, time off work, and nonmedical costs. Patients were most concerned with discussing cancer recurrence (76%), physical quality of life (70%), mortality (61%), and mental quality of life (52%) with their providers at follow-up visits.

CONCLUSION

Patients with early stage HPV-related oropharyngeal cancers are interested in altered surveillance approaches, experience significant burdens related to surveillance visits, and have concerns that are not well addressed with current surveillance approaches, including physical and mental quality of life. Optimized surveillance approaches should incorporate patient priorities and minimize associated burdens.

IMPLICATIONS FOR PRACTICE

The number of patients with HPV-related oropharyngeal cancers is increasing, and numerous clinical trials are investigating novel approaches to treating these good-prognosis patients. There has been limited work assessing optimal surveillance paradigms in these patients. Patients experience significant appointment-related burdens and have concerns such as physical and mental quality of life. Additionally, patients with early stage HPV-related oropharyngeal cancers express interest in altered surveillance approaches that decrease in-person clinic visits. Optimization of surveillance paradigms to promote broader survivorship care in clinical practice is needed.

Radiation Therapy Alone for Human Papillomavirus-Related Squamous Cell Carcinoma of the Oropharynx: A Single-Arm, Phase 2 Study

PURPOSE

Human papillomavirus (HPV)-related squamous cell carcinoma of the oropharynx (OPSCC) is extremely radiosensitive. Radiation therapy plus high-dose cisplatin remains the standard of care but causes long-term toxicity. Treatment deintensification approaches that reduce toxicity while maintaining survival are desirable for HPV-related OPSCC.

METHODS AND MATERIALS

We conducted a single-arm, multicenter, phase 2 trial. Patients with newly diagnosed, biopsy-proven, American Joint Committee on Cancer (seventh edition) stage III or IV OPSCC positive for both p16 and HPV DNA were eligible. Patients with T4, N3, or T1N1 disease were excluded. Smoking history was not included in eligibility criteria. Patients received intensity modulated radiation therapy (IMRT) of 70 Gy in 35 fractions or 70.4 Gy in 32 fractions without chemotherapy. The primary endpoint was complete response or complete metabolic response 10 weeks after IMRT completion.

RESULTS

Between September 13, 2013, and November 15, 2016, 39 patients were enrolled according to a 2-stage Simon design. Twenty-three patients (59%) had smoked for more than10 pack-years. Thirty-six patients (92%) had tumors genotyped as HPV16. Thirty-seven patients (95%) received full-dose radiation therapy and 35 (90%) had complete response or complete metabolic response. Median follow-up was 51 months (interquartile range, 41-63 months). One patient (3%) had regional recurrence and 3 (8%) had distant metastasis. One patient died of disease. The 2-year progression-free survival rate was 94% (95% CI, 81%-99%), and the 2-year overall survival rate was 100%. Common grade 3 adverse events during IMRT included mucositis in 10 patients (26%) and dysphagia in 7 patients (18%). No patients were dependent on a feeding tube at 1 month after IMRT completion. No grade 3 or 4 late adverse events were observed.

CONCLUSIONS

IMRT alone is associated with excellent response as well as reduced toxicity and could be a treatment option for carefully selected patients with locally advanced "true" HPV-related OPSCC. Further studies are warranted.

Surveillance imaging for patients with head and neck cancer treated with definitive radiotherapy: A partially observed Markov decision process model

BACKGROUND

A possible surveillance model for patients with head and neck cancer (HNC) who received definitive radiotherapy was created using a partially observed Markov decision process. The goal of this model is to guide surveillance imaging policies after definitive radiotherapy.

METHODS

The partially observed Markov decision process model was formulated to determine the optimal times to scan patients. Transition probabilities were computed using a data set of 1508 patients with HNC who received definitive radiotherapy between the years 2000 and 2010. Kernel density estimation was used to smooth the sample distributions. The reward function was derived using cost estimates from the literature. Additional model parameters were estimated using either data from the literature or clinical expertise.

RESULTS

When considering all forms of relapse, the model showed that the optimal time between scans was longer than the time intervals used in the institutional guidelines. The optimal policy dictates that there should be less time between surveillance scans immediately after treatment compared with years after treatment. Comparable results also held when only locoregional relapses were considered as relapse events in the model. Simulation results for the inclusive relapse cases showed that <15% of patients experienced a relapse over a simulated 36-month surveillance program.

CONCLUSIONS

This model suggests that less frequent surveillance scan policies can maintain adequate information on relapse status for patients with HNC treated with radiotherapy. This model could potentially translate into a more cost-effective surveillance program for this group of patients.

Management of the Neck in Squamous Cell Carcinoma of the Oral Cavity and Oropharynx: ASCO Clinical Practice Guideline

PURPOSE

The aim of the current work is to provide evidence-based recommendations to practicing physicians and others on the management of the neck in patients with squamous cell carcinoma of the oral cavity and oropharynx.

METHODS

ASCO convened an Expert Panel of medical oncology, surgery, radiation oncology, and advocacy experts to conduct a literature search, which included systematic reviews, meta-analyses, randomized controlled trials, and prospective and retrospective comparative observational studies published from 1990 through 2018. Outcomes of interest included survival, regional disease control, neck recurrence, and quality of life. Expert Panel members used available evidence and informal consensus to develop evidence-based guideline recommendations.

RESULTS

The literature search identified 124 relevant studies to inform the evidence base for this guideline. Six clinical scenarios were devised; three for oral cavity cancer and three for oropharynx cancer, and recommendations were generated for each one.

RECOMMENDATIONS

For oral cavity cancers, clinical scenarios focused on the indications for and the hallmarks of a high-quality neck dissection, indications for postoperative radiotherapy or chemoradiotherapy, and whether radiotherapy alone is sufficient elective treatment of an undissected neck compared with high-quality neck dissection. For oropharynx cancers, clinical scenarios focused on hallmarks of a high-quality neck dissection, factors that would favor operative versus nonoperative primary management, and clarifying criteria for an incomplete response to definitive chemoradiation for which salvage neck dissection would be recommended. Consensus was reached and recommendations were made for all six clinical scenarios. Additional information is available at www.asco.org/head-neck-cancer-guidelines .

FDG-PET/CT improves detection of residual disease and reduces the need for examination under anaesthesia in oropharyngeal cancer patients treated with (chemo-)radiation

PURPOSE

Early detection of residual disease (RD) after (chemo)radiation for oropharyngeal (OPC) is crucial. Surveillance of neck nodes with FDG-PET/CT has been studied extensively, whereas its value for local RD remains less clear. We aim to evaluate the diagnostic value of post-treatment FDG-PET/CT in detecting local RD and the outcome of patients with local RD.

METHODS

A cohort (n = 352) of consecutively treated OPC patients at our institute between 2010 and 2017 was evaluated. Patients that underwent FDG-PET/CT at 3 months post-treatment (n = 94) were classified as having complete (CMR) or partial metabolic response (PMR). PMR was defined as visually detectable metabolic activity above the background of surrounding normal tissues. Primary endpoint was diagnostic accuracy in detecting local RD.

RESULTS

Local RD was seen in 19/352 patients (5%), all of them were HPV negative. The FDG-PET/CT had a sensitivity of 100% (8/8), specificity 85% (73/86), PPV 38% (8/21), NPV 100% (73/73), and accuracy 86%. Patients with local RD had significantly worse OS at 2 years, compared to those without (10 versus 88%, P < 0.001). In multivariable analysis, local RD remained a significant predictive factor for death with a hazard ratio of 11.9 (95% CI 5.8-24.3). The number of patients that underwent PET/CT increased over time (P < 0.001), whereas the number of patients that underwent EUA declined (P = 0.072).

CONCLUSION

FDG-PET/CT has excellent performance for the detection of RD, with the sensitivity and negative predictive value approaching 100%. Due to these excellent results is examination under anaesthesia today in the vast majority of the PET-negative cases not necessary anymore.

Magnetic Resonance-based Response Assessment and Dose Adaptation in Human Papilloma Virus Positive Tumors of the Oropharynx treated with Radiotherapy (MR-ADAPTOR): An R-IDEAL stage 2a-2b/Bayesian phase II trial

BACKGROUND

Current standard radiotherapy for oropharynx cancer (OPC) is associated with high rates of severe toxicities, shown to adversely impact patients' quality of life. Given excellent outcomes of human papilloma virus (HPV)-associated OPC and long-term survival of these typically young patients, treatment de-intensification aimed at improving survivorship while maintaining excellent disease control is now a central concern. The recent implementation of magnetic resonance image - guided radiotherapy (MRgRT) systems allows for individual tumor response assessment during treatment and offers possibility of personalized dose-reduction. In this 2-stage Bayesian phase II study, we propose to examine weekly radiotherapy dose-adaptation based on magnetic resonance imaging (MRI) evaluated tumor response. Individual patient's plan will be designed to optimize dose reduction to organs at risk and minimize locoregional failure probability based on serial MRI during RT. Our primary aim is to assess the non-inferiority of MRgRT dose adaptation for patients with low risk HPV-associated OPC compared to historical control, as measured by Bayesian posterior probability of locoregional control (LRC).

METHODS

Patients with T1-2 N0-2b (as per AJCC 7th Edition) HPV-positive OPC, with lymph node <3 cm and <10 pack-year smoking history planned for curative radiotherapy alone to a dose of 70 Gy in 33 fractions will be eligible. All patients will undergo pre-treatment MRI and at least weekly intra-treatment MRI. Patients undergoing MRgRT will have weekly adaptation of high dose planning target volume based on gross tumor volume response. The stage 1 of this study will enroll 15 patients to MRgRT dose adaptation. If LRC at 6 months with MRgRT dose adaptation is found sufficiently safe as per the Bayesian model, stage 2 of the protocol will expand enrollment to an additional 60 patients, randomized to either MRgRT or standard IMRT.

DISCUSSION

Multiple methods for safe treatment de-escalation in patients with HPV-positive OPC are currently being studied. By leveraging the ability of advanced MRI techniques to visualize tumor and soft tissues through the course of treatment, this protocol proposes a workflow for safe personalized radiation dose-reduction in good responders with radiosensitive tumors, while ensuring tumoricidal dose to more radioresistant tumors. MRgRT dose adaptation could translate in reduced long term radiation toxicities and improved survivorship while maintaining excellent LRC outcomes in favorable OPC.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT03224000; Registration date: 07/21/2017.