Introduction
Head and neck cancer (HNC) is a morbid illness affecting approximately 70,000 new patients in the United States annually. 1 This disease often necessitates multidisciplinary treatment including surgery, radiotherapy (RT) and chemotherapy. RT for HNC often consists of 60 to 70 Gy delivered in 30 to 35 daily fractions to the site of the primary tumour or surgical bed and the draining lymphatics. Reference Grégoire, Evans and Le2 To reduce the risk of osteoradionecrosis (ORN) of the mandible after RT, pre-RT management is critical. Reference Watson, Dorna Mojdami and Oladega3 The standard of care pre-RT workflow includes a dental evaluation for ORN risk assessment and risk-adapted extractions to areas deemed high-risk for complications after RT. Reference Lajolo, Gioco and Rupe4 “High-risk” is not well-defined in the literature Reference Yang, Wong and Zakeri5 but is determined by the examining dentist with information from the radiation oncologist (RO) including anticipated dose and target. Reference Morrish, Chan and Silverman6,Reference Devi and Singh7 If extractions are necessary, many institutions perform them prior to RT planning, as anatomic changes after extractions may affect the dose distribution. This planning process takes one to two weeks, and only after this plan is finalized can the true dose be determined.
Since it is only after extractions occur that the RT planning process can begin, the RO is often asked to estimate mandibular exposure based on clinical information available at consult. Few studies have explored the accuracy of an ROs estimation of mandibular dose or have qualified strict criteria that define high-risk from the dental perspective. Reference Studer, Glanzmann and Studer8 Thus, there exist significant knowledge gaps. The consequences of inaccurate over- or under-estimation of mandible exposure may lead to a misinformed interpretation of risk and unnecessary or inadequate extractions, which delay care and impact quality of life. Since the time from HNC diagnosis to RT initiation is related to survival Reference Ang, Trotti and Brown9–Reference Mackillop, Bates and O’Sullivan12 , more effective evaluation methods are needed.
As a foundation for enhancing pre-RT management for HNC patients, we sought to examine the dentists’ approach, focusing on the factors influencing their decision-making. The information currently being used (i.e., various dose parameters) in practice by dentists evaluating HNC patients and the method by which this is communicated is highly heterogeneous. Reference Lee, Koom and Lee13 We sought to study their process as a foundation for improving workflows in radiation oncology and bridging the knowledge gap that exists between ROs and dentists during the complex and high-stakes pre-RT evaluation process.
Methods
Sampling and recruitment
Eligible participants included dentists who care for HNC patients from various backgrounds, including community dentists and quaternary care centre specialists, and regions, including the Southeastern and Midwestern United States. Dentists were selected based on institutional collaboration. They were contacted by the first and last authors (C.M. L. and R.T.H.) by email with a study description. If interested, they were sent a formal IRB approved document describing the study and their rights as participants. The Institutional Review Board of the Wake Forest University School of Medicine approved this study (IRB00096065).
Data collection
Interview data were collected from March 2023 to July 2023 over video teleconference. We obtained verbal consent for the interview and for the interview to be recorded. To gather comprehensive data surrounding the creation of a pre-RT dental evaluation and extraction plan, we employed the Consolidated Framework for Implementation Research (CFIR) and the Theoretical Domains Framework (TDF). The CFIR Reference Damschroder, Aron and Keith14,Reference Safaeinili, Brown-Johnson and Shaw15 and TDF Reference Atkins, Francis and Islam16,Reference Cane and O’Connor17 are comprehensive frameworks designed to guide the systematic assessment of factors influencing the implementation of evidence-based practices. The CFIR is tailored to identifying collective-level domains whereas the TDF is tailored to identifying individual-level determinants. Combined, these frameworks provide a broad platform for understanding the extraction planning process. The respective CFIR and TDF domains are listed in Table 1. The interviews were semi-structured. The interview guide and scripts were developed through collaboration with experts in head and neck radiation oncology, qualitative research and implementation science. The interviews were conducted by the first author (C.M.L.). The guide was loosely followed, and the interviews conducted conversationally. Interviews ranged from 30 to 60 minutes. They were transcribed by video-teleconference software. Thematic saturation was determined to have been achieved when no new insights emerged, indicating the data collected were sufficient to understand the process comprehensively. Once thematic saturation was reached, no further interviews were conducted.
Table 1. Quantification of domain strength within Pre-RT dental extraction interviews
Analysis
Interview transcripts were extracted from the teleconference software. The transcripts were reviewed by two independent reviewers (C.M.L. and S.E.G.) who organized and analysed the data. Reviewers utilized a directed content analysis method, applying predetermined codes from the CFIR and TDF constructs and domains. Specifically, reviewers focused on identifying any remarks related to their decision-making process within a relevant construct. Every comment was analysed to determine relevance relating to the predetermined constructs and organized accordingly. After data extraction was complete, the lead author reviewed the entirety of the coding to assess for consensus and determine discrepancies. Once consensus was achieved, researchers identified key domains qualitatively and quantitatively. Subthemes were identified and described.
Results
Of the five dentists approached to participate in the interview, all five agreed and ultimately enrolled and participated. All interviewees were female. The mean number of years in practice was 12.6 (range 3—35). Three participants worked in academic referral centres and two participants worked in community-based practices.
Multiple domains were identified as integral to the pre-RT extraction planning process. Key domains included process (CFIR), knowledge (TDF) and beliefs about consequences (TDF). Key domains were determined qualitatively and quantitatively.
Qualitative assessment
Qualitatively, key domains were identified based on the strength, valence and emphasis placed on the subjects discussed within these domains by the interviewed dentists. Strength was measured by the frequency of mentions and detailed discussions within a domain during the interviews and is further explored in the quantitative analysis. Valence was assessed through the positive or negative sentiments expressed by dentists within a domain. Emphasis was determined by detail and priority given during the interview. Within the beliefs about consequences domain, one interviewee described a patient’s prior dental health as “the most critical thing to look for.” Detailed descriptions were often found within the context of the process domain, indicating its critical role in process. Similarly, material within the knowledge domain was emphasized for its importance in guiding clinical decisions and management. These qualitative findings correlated well with the quantitative data to follow.
Quantitative assessment
Key domains were quantified by calculating the sum of quotes attributed to a domain by each coder and calculating the average quotes per domain. The average number of quotes attributed to each domain was 6.9 (SD 5·7). Those domains with ten or more quotes attributed to them by each reviewer were identified. The average number of quotes attributed to each of the key domains was at least one standard deviation above the average. The process domain was found to be the most integral with an average of 19·5 quotes attributed to it. Knowledge had the second most quotes attributed to it, with an average of 18. Beliefs about consequences was third with an average of 15 quotes attributed to it. This alignment between qualitative and quantitative data reinforces the significance. Additional details regarding the number of quotes attributed to each domain by each coder can be found in Table 1.
Process domain
Within the process domain, coordination among providers and a thorough pre-treatment consultation were identified as significant themes. Important stakeholders include the otolaryngologist, the RO, the patient and the patient’s dentist (if they had a dentist prior to their cancer diagnosis). As described by one interviewee, ‘there’s three, really maybe four, main people I’m getting all my information from: It’s the ENT surgeon, the folks over in radiation, the patient themselves, and of course, if they’ve seen a dentist, the patient’s dentist’. Collaboration and information sharing among stakeholders is crucial for effective care coordination. Multidisciplinary conferences and communication channels help to facilitate collaboration and ensure comprehensive care and planning.
Another important part of the dentist’s process is their consultation before which they gather information from various resources, including previously identified stakeholders, the medical record and a thorough review of radiographic imaging. During the initial pre-RT dental consultation, dentists assess the patient’s dental status through a thorough review of their dental history, a comprehensive dental exam and same day radiographs. Dentists are self-reported visual providers; radiographs and physical exams are crucial parts of their process. The initial consultation helps dentists assess the impact RT will have on the patient’s dental health such that they can make the appropriate recommendations.
Knowledge domain
Within the knowledge domain, the dentists’ understanding of the radiation plan was revealed as an important theme. It is important for dentists to understand the plan, including the dose distribution and target areas, to anticipate dental complications and tailor recommendations accordingly. One interviewee describes the utility of a visual aid depicting anticipated RT dose maps: ‘ideally, we would have some type of drawn-out map’. Currently, they are left guessing: ‘I have to guess the radiation map and then make the recommendations from there…which is not the best’.
Dentists must also be aware of the impact radiation has on a patient’s global dental health, including its effects on salivary glands and its ability to compromise blood supply and decrease healing. Knowledge of the patient’s comorbidities influences treatment decisions and the risk assessment for complications. Dentists must tailor their recommendations based on a patient’s dental health including their dental history and even factors such as tooth morphology which could impact ease of extraction. As one interviewee noted, radiation ‘changes the number of cells you have to grow new bone… the blood supply that supplies those cells to grow new bones…their ability to rebound from extractions afterwards is very compromised’. Knowledge of these key factors are crucial for optimizing outcomes.
Beliefs about consequences domain
Within the beliefs about consequences domain, the impact of a patient’s dental and medical health was identified as highly significant. Subjective assessments of patient habits and their oral health history crucially guide a dentist’s beliefs about the necessity of extractions to prevent complications. As described by one interviewee: ‘I think [a patient’s dental habits], to me, are the most critical thing to look for… because they don’t, they can’t change that habit during their cancer therapy, it’s just an unreasonable expectation’. Patients can have pristine dentition but if they have previously not prioritized their dental health, they may still go on to develop complications: ‘My experience has been that if they don’t floss and they’re only brushing episodically, but they’ve been resistant to decay before, all bets are off’. Thus, dentists prioritize a patient’s prior dental health maintenance when making extraction plans over the appearance of their dentition on the day of consultation.
Additional health history informs their beliefs and extraction plans. Behaviour-related risk factors for their disease such as smoking and alcohol consumption shape dentists’ expectations. Each of these domains and their relevant subthemes play a significant role in the dentist’s decision-making process, with no one determinant being the deciding factor. Further relevant quotations can be found in Table 2. As aptly described by one interviewee, ‘it’s hard to say, you know, what one thing [is most important], because they’re all so interconnected for us…we don’t make these decisions willy nilly’.
Table 2. Relevant quotations by domain
Discussion
The current pre-radiotherapy dental evaluation process is nuanced and time-consuming, yet crucial for optimizing patient outcomes in radiation oncology Reference Rosenthal, Liu and Lee11,Reference Graboyes, Garrett-Mayer and Ellis18 . A generic pre-RT flowchart is shown in Figure 1, demonstrating the multiple steps that must be taken before a patient can begin their treatment. Efforts to improve upon this process may improve patient quality of life and cancer outcomes. One step in this process is the dental evaluation and extractions (if necessary). Little is known about how dentists evaluate head and neck patients prior to radiation and if there is anything radiation oncologists can do to assist in streamlining and improving their process. Through qualitative interviews with dentists, several key determinants were identified. Specifically, dentists navigate a multi-step process involving collaboration with key stakeholders and a comprehensive pre-extraction evaluation. Communication among providers and thorough data gathering are essential for informed decision making. Understanding the proposed RT plan, is vital for anticipating dental complications and tailoring recommendations. Dentists must also consider the impact of radiation on various aspects of dental and overall health. Subjective assessments of patient habits, oral health history and health status significantly influence the need for extractions to prevent complications.
Figure 1. Flowchart depicting the pre-radiation workup and radiation planning process.
Specific challenges must be overcome to prevent delays in pre-RT dental care, given the importance of rapid initiation of RT on cancer outcomes Reference Shaikh, Handorf and Murphy10 . ROs may recognize that one of the key determinants in the dentist’s pre-RT evaluation process is knowledge about the radiation plan Reference Studer, Glanzmann and Studer8 . The above interviews demonstrate that visual depictions of an anticipated RT plan could potentially be helpful, but a streamlined framework for that to occur does not exist. Radiographs and physical exam were emphasized as part of their initial evaluation. Visual depictions of radiation doses were directly requested. Dentists want to see where the radiation is going.
There is precedent in the literature for predicting radiation dose to the mandible ahead of the actual treatment planning scan. One prior study retrospectively examined clinical factors to create predictive models of maximum RT dose to the mandible Reference Tsai, Verma and Owosho19 . This study demonstrated the feasibility of a clinical model approach, though it had limitations. For instance, this model was built upon an older dataset and modern RT techniques will result in different dose distributions. Additionally, when they designed their model, only a few clinical factors were evaluated, and RT target and planned dose were not included.
Another case series created mandibular RT dose maps for 18 common HNC clinical scenarios Reference Polce, Gogineni and Antone20 . This provided a representation of mandible exposure for patients with HNC of various primary sites treated with either definitive or postoperative RT, as both factors (location of primary tumour and treatment intent) substantially affect the magnitude and distribution of mandible dose. These dose maps are a useful visual reference but are limited by their small sample size, presenting individual, representative cases for each scenario.
A more recent study trained an artificial intelligence (AI)-guided tool to predict mandibular dose. This required target volumes to be manually delineated on a diagnostic computed tomography (CT) scan before making the prediction. This is a time-consuming task that necessitates duplication of work after any dental extractions occur. There were strong correlations between the AI-based prediction and that of the expert physician and the AI model’s predictions showed higher concordance with the true value than the expert physician’s Reference Chan, Hohenstein and Carpenter21 .
These preliminary studies demonstrate an interest in and a need for better estimation of radiation dose prior to RT planning. Any predictive tool would benefit from being larger in scale in terms of retrospective clinical input. Visual representations created in preliminary studies proved useful. Based on our findings, a visual representation of dose would likely play an important part of the dentist’s process and a valuable resource prior to their consultation with the patient and when planning dental extractions. A flowchart demonstrating where in the process a dentist would be likely to utilize the radiation dose maps can be found in Figure 2.
Figure 2. Flowchart depicting the pre-radiation dental evaluation and extraction planning process.
The most recent preliminary study suggests that AI can serve as an accurate tool in closing this crucial information gap. Taking our findings from the current study in the context of the available literature, methods for predicting the dose to the mandible prior to RT planning should be based on several factors including but not limited to primary tumour site, treatment intent (definitive versus postoperative), tumour and nodal classification, anticipated RT target volumes and doses and the pre-RT diagnostic imaging. The output should include multiple mandibular dosimetric parameters (e.g., maximum point dose, volumes receiving at least 50 or 60 Gy), and a visual representation of isodose distributions relevant to dental planning (e.g., isodose lines representing volumes of tissue/mandible receiving at least 50, 60 and 70 Gy) Reference Levi22,Reference Treister, Brennan and Sollecito23 . These visual aids could either be projected onto a single axial image, or as a 2- or 3-dimensional representation to facilitate multimodal communication.
This study has limitations. Our sample was comprised of dentist in the authors’ practice network. Thus, it is possible that our findings have limited relevance to dentists in other settings. Further, we included very few participants, even for a qualitative study. Future studies should include a larger and more diverse cohort. Additionally, ideally, we would have gathered other data (e.g., observational) to triangulate interview data to enhance confirmability. Nevertheless, our participants had diverse clinical backgrounds, and their input was consistent in theme, suggesting that our findings are reasonably credible and transferrable.
Conclusion
Pre-RT dental management is critical in HNC patients. It is a complex, nuanced task that must be completed expeditiously to avoid treatment delays. A more streamlined process may enhance the quality and efficiency of pre-RT dental management. As the first study to qualitatively explore pre-RT dental evaluations using an implementation science framework, we demonstrate that there are key determinants that are ripe for innovation and improvement. Specifically, development of clinically useful RT dose prediction processes that facilitate multi-modal communication of predicted dose to dental colleagues is direly needed.
Financial support
There is no funding to disclose.
Competing interests
No authors have any conflicts of interest to disclose.
Previous Presentations
Abstract presented at the American Radium Society Meeting in Palm Springs, CA in May 2024.
Ethics Approval Statement
All activities performed in studies involving human participants were in accordance with the ethical standards or the institution and with the Helsinki declaration.
Patient Consent Statement
All involved persons gave their informed consent prior to study inclusion.
Open access
