Trends and Disparities of Proton Therapy Use among Patients with Head and Neck Cancer: Analysis from the National Cancer Database (2005-14)

Proton therapy for primary and recurrent HPV-related oropharyngeal cancer

The incidence of Human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OPSCC) has risen over the past two decades, now accounting for 44-75 % of cases in Europe and the USA. This review synthesized data from PubMed, additional academic sources, and ongoing studies to summarize the potential role of proton therapy (PT) role in treating HPV-related OPSCC. In vitro studies support PT radiosensitization of HPV-positive cells and clinical experiences report high locoregional control (LRC) rates of 88.6-97 % with significantly reduced side effects such as xerostomia by 12.5 % and brain necrosis by 2.3 %, compared to intensity-modulated radiation therapy (IMRT). A randomized trial (NCT01893307) has also recently provided level 1 evidence showing that PT is non-inferior to IMRT for tumor control while reducing treatment-related toxicities, such as feeding tube dependence (28 % vs. 42 %, p = 0.019) and facilitating better work resumption outcomes (71 % vs. 52 % at 2 years). Despite the success of radiation de-escalation achieving LRC up to 95 %, recent trials indicate potential survival risks when standard treatments are modified. Failure pattern analysis showed that up to 70 % of locoregional recurrences occurred in-field, highlighting the potential role of PT in achieving LRC while minimizing toxicity. PT could also play a role in the reirradiation of recurrent OPSCC, with reported 1-year LRC rates of 71.8-80.8 %, 2-year LRC rates of 72.8-80.3 %, 1-year overall survival (OS) rates of 65.2-81.3 %, 2-year OS rates of 32.7-69 %, and late grade ≥2 toxicities of 11.9-36.3 %. Methodologies improving reRT approaches include dose/volume histogram comparisons, which recommended PT when it resulted in lower predicted toxicities.

Acute toxicities in proton therapy for head and neck cancer - A matched analysis of the DAHANCA 35 feasibility study

Background and purpose

As preparation for a national randomized study comparing proton radiotherapy to photon radiotherapy, DAHANCA 35, we performed a non-randomized pilot study to investigate patient selection, logistics, planning, and treatment delivery. With the present study, as a comprehensive safety analysis, we want to compare toxicity during and up to two months after therapy to a historically matched group of patients treated with photon radiotherapy.

Materials and methods

62 patients treated with protons were matched to 124 patients who received photon treatment outside a protocol. Available data were retrieved from the DAHANCA database. Patients were matched on treatment centre, concurrent chemotherapy, tumour site, stage, p16 status for oropharynx cancers. Selection of patients for proton therapy was based on comparative treatment plans with a NTCP reduction for dysphagia and xerostomia at six months.

Results

Baseline characteristics between groups were well balanced, except for the type of drug used concurrently; more photon patients received Carboplatin (21.2 % vs 5.8 %, p = 0.01). Proton therapy was associated with significantly less weight loss at the end of treatment, mean weight loss of 3 % for protons and 5 % for photons (p < 0.001). There were more grade 3 skin reactions and grade 3 mucositis after proton treatment compared with photons at the end of treatment, Risk Ratio (RR) 1.9 (95 % CI: 1.01-3.5, p = 0.04) and RR 1.5 (95 % CI: 1.3-1.7, p < 0.001), respectively. All differences resolved at follow up two months after treatment. There were no significant differences between groups on opioid use, use of feeding tubes, or hospitalization during the observation period.

Conclusion

Proton treatment resulted in excess objective mucositis and dermatitis, which was transient and did not seem to negatively influence weight or treatment compliance and intensity. Selection bias was likely especially since NTCP models were used for selection of proton treatment and photon treated patients were matched manually. We are currently including patients in a randomized controlled trial.

Current Status and Future Directions of Proton Therapy for Head and Neck Carcinoma

The growing interest in proton therapy (PT) in recent decades is justified by the evidence that protons dose distribution allows maximal dose release at the tumor depth followed by sharp distal dose fall-off. But, in the holistic management of head and neck cancer (HNC), limiting the potential of PT to a mere dosimetric advantage appears reductive. Indeed, the precise targeting of PT may help evaluate the effectiveness of de-escalation strategies, especially for patients with human papillomavirus associated-oropharyngeal cancer (OPC) and nasopharyngeal cancer (NPC). Furthermore, PT could have potentially greater immunogenic effects than conventional photon therapy, possibly enhancing both the radiotherapy (RT) capability to activate anti-tumor immune response and the effectiveness of immunotherapy drugs. Based on these premises, the aim of the present paper is to conduct a narrative review reporting the safety and efficacy of PT compared to photon RT focusing on NPC and OPC. We also provide a snapshot of ongoing clinical trials comparing PT with photon RT for these two clinical scenarios. Finally, we discuss new insights that may further develop clinical research on PT for HNC.

Considerations for study design in the DAHANCA 35 trial of protons versus photons for head and neck cancer

Proton radiotherapy offers a dosimetric advantage compared to photon therapy in sparing normal tissue, but the clinical evidence for toxicity reductions in the treatment of head and neck cancer is limited. The Danish Head and Neck Cancer Group (DAHANCA) has initiated the DAHANCA 35 randomised trial to clarify the value of proton therapy (NCT04607694). The DAHANCA 35 trial is performed in an enriched population of patients selected by an anticipated benefit of proton therapy to reduce the risk of late dysphagia or xerostomia based on normal tissue complication probability (NTCP) modelling. We present our considerations on the trial design and a test of the selection procedure conducted before initiating the randomised study.

Patients' needs in proton therapy: A survey among ten European facilities

Aims

The number of Proton Therapy (PT) facilities is still limited worldwide, and the access to treatment could be characterized by patients' logistic and economic challenges. Aim of the present survey is to assess the support provided to patients undergoing PT across Europe.

Methods

Through a personnel contact, an online questionnaire (62 multiple-choice and open-ended questions) via Microsoft Forms was administered to 10 European PT centers. The questionnaire consisted of 62 questions divided into 6 sections: i) personal data; ii) general information on clinical activity; iii) fractionation, concurrent systemic treatments and technical aspects of PT facility; iv) indication to PT and reimbursement policies; v) economic and/ or logistic support to patients vi) participants agreement on statements related to the possible limitation of access to PT. A qualitative analysis was performed and reported.

Results

From March to May 2022 all ten involved centers filled the survey. Nine centers treat from 100 to 500 patients per year. Paediatric patients accounted for 10-30%, 30-50% and 50-70% of the entire cohort for 7, 2 and 1 center, respectively. The most frequent tumours treated in adult population were brain tumours, sarcomas and head and neck carcinomas; in all centers, the mean duration of PT is longer than 3 weeks. In 80% of cases, the treatment reimbursement for PT is supplied by the respective country's Health National System (HNS). HNS also provides economic support to patients in 70% of centers, while logistic and meal support is provided in 20% and 40% of centers, respectively. PT facilities offer economic and/or logistic support in 90% of the cases. Logistic support for parents of pediatric patients is provided by HNS only in one-third of centers. Overall, 70% of respondents agree that geographic challenges could limit a patient's access to proton facilities and 60% believe that additional support should be given to patients referred for PT care.

Conclusions

Relevant differences exist among European countries in supporting patients referred to PT in their logistic and economic challenges. Further efforts should be made by HNSs and PT facilities to reduce the risk of inequities in access to cancer care with protons.

Head and Neck Cancer Types and Risks of Cervical-Cranial Vascular Complications within 5 Years after Radiation Therapy

Background and purpose: to investigate the frequency of cervical−cranial vascular complications soon after radiation therapy (RT) and identify differences among patients with various types of head and neck cancer (HNC). Methods: We enrolled 496 patients with HNC who had received their final RT dose in our hospital. These patients underwent carotid duplex ultrasound (CDU) for monitoring significant carotid artery stenosis (CAS). Brain imaging were reviewed to detect vertebral, intracranial artery stenosis, or preexisted CAS before RT. Primary outcome was significant CAS at the internal or common carotid artery within first 5 years after RT. We categorized the patients into nasopharyngeal carcinoma (NPC) and non-NPC groups and compared the cumulative occurrence of significant CAS between the groups using Kaplan−Meier and Cox-regression analyses. Results: Compared to the NPC group, the non-NPC group had a higher frequency of significant CAS (12.7% vs. 2.0%) and were more commonly associated with significant CAS after adjusting the covariates (Adjusted hazard ratio: 0.17, 95% confident interval: 0.05−0.57) during the follow-up period. All the non-NPC subtypes (oral cancer/oropharyngeal, hypopharyngeal, and laryngeal cancers) were associated with higher risks of significant CAS than the NPC group (p < 0.001 respectively). Conclusion: Significant CAS was more frequently noted within 5 years of RT among the patients with non-NPC HNC than among the patients with NPC. Scheduled carotid artery surveillance and vascular risk monitoring should be commenced earlier for patients with non-NPC HNC. By contrast, vascular surveillance could be deferred to 5 years after RT completion in NPC patients.

Association of Race With Receipt of Proton Beam Therapy for Patients With Newly Diagnosed Cancer in the US, 2004-2018

IMPORTANCE

Black patients are less likely than White patients to receive guideline-concordant cancer care in the US. Proton beam therapy (PBT) is a potentially superior technology to photon radiotherapy for tumors with complex anatomy, tumors surrounded by sensitive tissues, and childhood cancers.

OBJECTIVE

To evaluate whether there are racial disparities in the receipt of PBT among Black and White individuals diagnosed with all PBT-eligible cancers in the US.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study evaluated Black and White individuals diagnosed with PBT-eligible cancers between January 1, 2004, and December 31, 2018, in the National Cancer Database, a nationwide hospital-based cancer registry that collects data on radiation treatment, even when it is received outside the reporting facility. American Society of Radiation Oncology model policies were used to classify patients into those for whom PBT is the recommended radiation therapy modality (group 1) and those for whom evidence of PBT efficacy is still under investigation (group 2). Propensity score matching was used to ensure comparability of Black and White patients' clinical characteristics and regional availability of PBT according to the National Academy of Medicine's definition of disparities. Data analysis was performed from October 4, 2021, to February 22, 2022.

EXPOSURE

Patients' self-identified race was ascertained from medical records.

MAIN OUTCOMES AND MEASURES

The main outcome was receipt of PBT, with disparities in this therapy's use evaluated with logistic regression analysis.

RESULTS

Of the 5 225 929 patients who were eligible to receive PBT and included in the study, 13.6% were Black, 86.4% were White, and 54.3% were female. The mean (SD) age at diagnosis was 63.2 (12.4) years. Black patients were less likely to be treated with PBT than their White counterparts (0.3% vs 0.5%; odds ratio [OR], 0.67; 95% CI, 0.64-0.71). Racial disparities were greater for group 1 cancers (0.4% vs 0.8%; OR, 0.49; 95% CI, 0.44-0.55) than group 2 cancers (0.3% vs 0.4%; OR, 0.75; 95% CI, 0.70-0.80). Racial disparities in PBT receipt among group 1 cancers increased over time (annual percent change = 0.09, P < .001) and were greatest in 2018, the most recent year of available data.

CONCLUSIONS AND RELEVANCE

In this cross-sectional study, Black patients were less likely to receive PBT than their White counterparts, and disparities were greatest for cancers for which PBT was the recommended radiation therapy modality. These findings suggest that efforts other than increasing the number of facilities that provide PBT will be needed to eliminate disparities.

Radiation Oncology Alternative Payment Model and Large Urban Academic Centers: Future Implications for Patients and Providers

The radiation oncology alternative payment model (RO-APM) was developed by the Center for Medicare and Medicaid Innovation, a part of the Centers for Medicare & Medicaid Services, as a vehicle to optimize value for patients undergoing radiation therapy. By shifting reimbursement away from fee-for-service and toward a prospective bundled payment system, the RO-APM is intended to bend the cost curve in radiation oncology while preserving or even enhancing outcomes. As with prior large-scale policy initiatives, the nature and magnitude of the RO-APM's impact on care delivery will vary substantially depending on a host of local factors, including practice setting. Urban academic centers play a key role in radiation oncology by spearheading innovation, managing the most complicated cases, training the next generation of radiation oncologists, and often caring for vulnerable patient populations. Thus, to protect patients' access to this high-quality cancer care, it will be crucial to characterize the RO-APM's projected impact on large urban academic institutions before its implementation, including possible unintended adverse consequences. Here, we provide an overview of this seismic change in radiation oncology reimbursement and discuss its unique potential implications for large urban academic institutions as a means to facilitate necessary preparations and inform future revisions to the model.

Geospatial Disparities in Access to Proton Therapy in the Continental United States

Proton therapy (PT) is an important component of therapy for select cancers, but no formal study of geospatial access to PT has been conducted to date. Population data for 320.7 million people in 32,644 zip codes were analyzed. Median travel time was 1.61 (IQR 0.67-3.36) hours for children and 1.64 (IQR 0.69-3.33) hours for adults. Significant variation in travel time to nearest PT center was observed between states. The West has a longer median travel time of 3.51 (IQR 1.15-7.13) hours when compared to the Midwest (1.70, IQR 0.79-2.69), South (1.60, IQR 0.61-3.12) and Northeast (1.04, IQR 0.57-2.01).

Beam-Specific Spot Guidance and Optimization for PBS Proton Treatment of Bilateral Head and Neck Cancers

PURPOSE

A multi-field optimization (MFO) technique that uses beam-specific spot placement volumes (SPVs) and spot avoidance volumes (SAVs) is introduced for bilateral head and neck (H&N) cancers. These beam-specific volumes are used to guide the optimizer to consistently achieve optimal organ-at-risk (OAR) sparing with target coverage and plan robustness.

MATERIALS AND METHODS

Implementation of this technique using a 4-beam, 5-beam, and variant 5-beam arrangement is discussed. The generation of beam-specific SPVs and SAVs derived from target and OARs are shown. The SPVs for select fields are further partitioned into optimization volumes for uniform dose distributions that resemble those of single-field optimization (SFO). A conventional MFO plan that does not use beam-specific spot placement guidance (MFOcon) and an MFO plan that uses only beam-specific SPV (MFOspv) are compared with current technique (MFOspv/sav), using both simulated scenarios and forward-calculated plans on weekly verification computed tomography (VFCT) scans.

RESULTS

Dose distribution characteristics of the 4-beam, 5-beam, and variant 5-beam technique are demonstrated with discussion on OAR sparing. When comparing the MFOcon, MFOspv, and MFOspv/sav, the MFOspv/sav is shown to have superior OAR sparing in 9 of the 14 OARs examined. It also shows clinical plan robustness when evaluated by using both simulated uncertainty scenarios and forward-calculated weekly VFCTs throughout the 7-week treatment course.

CONCLUSION

The MFOspv/sav technique is a systematic approach using SPVs and SAVs to guide the optimizer to consistently reach desired OAR dose values and plan robustness.

Clinical Review of Proton Therapy in the Treatment of Unilateral Head and Neck Cancers

Radiotherapy is a common treatment modality in the management of head and neck malignancies. In select clinical scenarios of well-lateralized tumors, radiotherapy can be delivered to the primary tumor or tumor bed and the ipsilateral nodal regions, while intentional irradiation of the contralateral neck is omitted. Proton beam therapy is an advanced radiotherapy modality that allows for the elimination of exit-dose through nontarget tissues such as the oral cavity. This dosimetric advantage is apt for unilateral treatments. By eliminating excess dose to midline and contralateral organs at risk and conforming dose around complex anatomy, proton beam therapy can reduce the risk of iatrogenic toxicities. Currently, there is no level I evidence comparing proton beam therapy to conventional photon radiation modalities for unilateral head and neck cancers. However, a growing body of retrospective and prospective evidence is now available describing the dosimetric and clinical advantages of proton beam therapy. Subsequently, the intent of this clinical review is to summarize the current evidence supporting the use of proton beam therapy in unilateral irradiation of head and neck cancers, including evaluation of disease site-specific evidence, unique challenging clinical scenarios, and ongoing clinical trials.

Past, present and future of proton therapy for head and neck cancer

Proton therapy has recently gained substantial momentum worldwide due to improved accessibility to the technology and sustained interests in its advantage of better tissue sparing compared to traditional photon radiation. Proton therapy in head and neck cancer has a unique advantage given the complex anatomy and proximity of targets to vital organs. As head and neck cancer patients are living longer due to epidemiological shifts and advances in treatment options, long-term toxicity from radiation treatment has become a major concern that may be better mitigated by proton therapy. With increased utilization of proton therapy, new proton centers breaking ground, and as excitement about the technology continue to increase, we aim to comprehensively review the evidence of proton therapy in major subsites within the head and neck, hoping to facilitate a greater understanding of the full risks and benefits of proton therapy for head and neck cancer.