This cohort study assesses the benefit of providing frozen section control samples for use during intraoperative margin assessment for patients undergoing transoral robotic surgery for human papillomavirus-16–positive oropharyngeal squamous cell carcinoma.
Key Points
Question
Can the inclusion of frozen section controls during transoral robotic surgery for human papillomavirus (HPV)-16–positive oropharyngeal cancer improve intraoperative margin assessment?
Findings
In this cohort study of 170 patients with HPV-16–positive oropharyngeal squamous cell carcinoma, cauterized lymphoepithelial tissue during transoral robotic surgery presented challenges in intraoperative margin assessment. Providing a positive control (tumor biopsy), along with standard tumor margins for frozen sectioning, was associated with improved diagnostic sensitivity and reduced operative time in patients predisposed to cellular atypia, such as patients with prior radiation therapy or surgery.
Meaning
Providing positive intraoperative control samples may improve diagnostic accuracy of cancer margin assessment during transoral robotic surgery in patients with HPV-16–positive oropharyngeal cancer.
Abstract
Importance
Intraoperative margin assessment is an important technique for ensuring complete tumor resection in malignant cancers. However, in patients undergoing transoral robotic surgery (TORS) for oropharyngeal carcinomas, tissue artifact may provide pathologic uncertainty.
Objective
To assess the benefit of providing frozen section control samples (“positive tumor biopsies”) for use during intraoperative margin assessment for patients undergoing TORS for human papillomavirus (HPV)-16–positive oropharyngeal squamous cell carcinoma (OPSCC).
Design, Setting, and Participants
In this cohort study, patients receiving curative-intent TORS for biopsy-proven HPV-16–positive OPSCC performed by a single attending surgeon (A.H.M.) at Ronald Reagan UCLA Medical Center from 2017 to 2021 were included in a retrospective data analysis. Exclusion criteria included HPV-negative status, participation in clinical trials, and tumors of unknown primary origin.
Main Outcomes and Measures
Survival outcomes investigated included overall and disease-free survival. Adverse pathologic outcomes measured included occurrence of nondiagnostic margins and margin reversal from frozen to fixed pathology.
Results
Of the 170 patients included (mean [SD] age, 61.8 [9.9] years; 140 [82%] male), 50% of patients (n = 85) received a frozen section control. Use of a frozen section control was associated with statistically significantly improved sensitivity of intraoperative margin assessment, from 82.8% to 88.9% (difference, 6.1%; 95% CI, 3.9%-8.3%). Eleven percent (n = 18) of all tumors evaluated exhibited at least 1 nondiagnostic intraoperative margin, and 11% (n = 18) experienced margin reversal from frozen to fixed pathology. In patients with nondiagnostic margins, use of frozen section controls was associated with statistically significantly reduced time spent in the operating room (Cohen d, 1.14; 95% CI, 0.12-2.14).
Conclusions and Relevance
In this cohort study, frozen intraoperative margins assessed during TORS resections of HPV-16–positive OPSCC were diagnostically challenging. Adverse pathologic outcomes, such as margin status reversal from positive on frozen pathology to negative on formal analysis, were common. Providing intraoperative frozen section control biopsies may offer clarity in cases with nondiagnostic margins, reducing the need for additional sampling and time spent in the operating room.
Introduction
The incidence of oropharyngeal squamous cell carcinoma (OPSCC) in the US has risen dramatically in the past few decades, owing in large part to the rise in prevalence of human papillomavirus (HPV)-driven head and neck cancers.1,2 The advent of transoral robotic surgery (TORS) in the past 2 decades has reduced the surgical morbidity of tumor resection for these types of cancers.3,4,5 As such, TORS has rapidly become a mainstay in surgical management of oropharyngeal cancers.3,4,5,6
In the resection of head and neck tumors, margin assessment is generally regarded as one of the critical predictors of overall and disease-free survival.7,8,9 Given that complete surgical resection is an important prognostic factor, intraoperative assessment of frozen tumor margins is a common practice.10,11,12,13,14,15 Baddour et al16 noted that the practice of intraoperative frozen section analysis in resections of head and neck cancer displays high diagnostic accuracy, with more than 95% concurrence between intraoperative sectioning and final pathologic diagnosis. A study by Layfield et al17 of 1796 pairs of frozen and permanent sections found that discordance existed in only 3.1% of pairs. Other studies have concurred with these findings, with multiple articles reporting the accuracy and specificity of frozen margin analysis as above 90%.14,18,19 Reports of sensitivity are more variable, ranging from 47% to 99%.14,18,19
However, though intraoperative frozen section analysis is widely used and largely accurate, the practice is not without its pitfalls. Difficulties in tissue processing, such as inadequate sampling or artifacts from freezing and sectioning, may hamper the accuracy of this practice.18,20,21 Interestingly, tissue type may predispose certain tumors to errors in pathologic analysis. In the oral cavity, Weinstock et al23 have reported that some oral subsites have higher percentages of positive margins. Specifically, mucosal margins from tonsillar carcinomas experience greater tissue distortion than the muscle fibers in base-of-tongue tumors.15,21,22,23 Finally, frozen section analysis is heavily dependent on pathologist experience with head and neck cancer histologic grade. Laury et al24 noted that pathologists with more than 10 years of experiences tended to make fewer errors than their less-experienced colleagues. These studies suggest that there is room for improvement in the practice of intraoperative margin sampling.
Beyond the general limitations of frozen section analysis, intraoperative margin assessment in TORS carries its own unique set of difficulties. Method of tumor excision can substantially affect the quality of pathologic margin assessment.23,25,26 Although there is little data investigating the effect of various modes of excision on pathologic uncertainty, a study by Kakarala et al22 has shown that monopolar electrocautery is associated with considerable tissue distortion. These findings are particularly relevant for patients receiving TORS for oropharyngeal cancer because tumor extirpation is typically achieved with monopolar cautery. Additionally, tumors amenable to transoral resection are often of lower staging and may be more prone to challenging margin assessment. In several studies, disruption of normal tissue architecture was most evident in low-stage tumors because contraction of muscle fibers caused distortion of tumor margins on frozen and fixed histologic findings, whereas higher-stage tumors were less affected by the method of excision.22,23
Despite the unique limitations associated with intraoperative margin assessment in TORS, very little has been published investigating the accuracy, sensitivity, and specificity of this practice. At the University of California, Los Angeles, we noted that there was a higher incidence of margin uncertainty and requests for additional margin sampling in patients undergoing TORS for OPSCC compared with oral cavity and laryngeal cancers. The intention of this cohort study was to investigate the efficacy of a novel strategy for improving intraoperative diagnostic clarity following TORS for oropharyngeal cancer. In the present approach, we augmented the standard practice of requesting frozen sections of peripheral and deep margins by including an intraoperative tumor biopsy (“frozen section control”). The intention of this strategy was to provide a “positive control” sample for comparative use in margin assessment. Additionally, we sought to determine whether specific clinical characteristics predisposed patients with oropharyngeal cancer to margin uncertainty following curative TORS resections.
Methods
Cohort
A retrospective medical record review was conducted of all patients receiving TORS performed by a single attending surgeon (A.H.M.) at Ronald Reagan UCLA Medical Center from 2017 to 2021. The University of California, Los Angeles institutional review board granted approval for this study and deemed patient informed consent unnecessary owing to use of deidentified data. Exclusion criteria included patients with tumors of unknown origin, patients without preoperative pathologic confirmation of oropharyngeal carcinoma, and patients without at least 3 months of follow-up to avoid immortal patient bias. Patients with HPV-negative tumors were also excluded because they comprised a relatively small percentage of patients and risked biasing analysis with confounding variables. Patients with known preoperative clinical tumor stages of III and IV were also excluded to standardize the difficulty of tumor ablation. Patients who participated in the concurrent institutional KESTREL phase 3 trial were excluded; this trial provided preoperative stereotactic body irradiation, which was thought to confound pathologic analysis of tissue architecture.
Measurements and Outcomes
At a minimum, tumor margins were sampled from the tumor specimen along 4 peripheral borders, as well as a deep margin along the apex of the tumor. Care was taken to mark the orientation of the removed tumor specimen so that in the event of unclear or positive margins, additional peripheral samples could be accurately taken to assess for complete resection. Our use of intraoperative control biopsies began routinely in 2019; thus, patients who received TORS prior to the start time did not have control biopsies and served as the comparative group. Margins that were seen to be consistent with a diagnosis of at least moderate dysplasia, carcinoma in situ, or carcinoma were considered to be positive in accordance with a consensus of head and neck surgeons published in a previous study by Bulbul et al.27 Margins with low-grade dysplasia, atypical cellular architecture without features of cancer, were designated as negative. Nondiagnostic intraoperative margins were defined as samples with atypical cells, which required further sampling for diagnosis.
Clinical and demographic information of patients was collected via electronic medical record review. Variables collected included age, sex, race, tumor TNM staging, tumor site, frozen and fixed margin status, surgery performed, operating room resource utilization, adjuvant therapy, and clinical course, including information regarding recurrence or death. Patient comorbidity was scored using the Adult Comorbidity Evaluation instrument. Tumors were staged retroactively according to American Joint Committee on Cancer staging manual, 8th edition, guidelines based on operative notes and imaging reports. Outcomes of interest included overall survival, disease-free survival, and adverse pathologic events. Overall survival was calculated as the time from initial pathologic diagnosis to death; disease-free survival was determined to be time from diagnosis to pathologic confirmation of recurrence.
Adverse pathologic events were also examined. First, the number of additional margins required to clarify a nondiagnostic intraoperative margin was collected. We also investigated frozen-fixed diagnosis mismatches as adverse pathologic events to determine whether any clinical indicators predisposed patients to margin uncertainty. Nondiagnostic margins were not considered in the assessment of margin reversal because they did not provide definitive pathologic confirmation. Additional outcomes of interest included use of hospital resources, including length of time spent in the operating room and length of postoperative hospital stay. Ultimate intraoperative margin status was the margin status at the conclusion of the case, after all margin resampling.
Statistical Analysis
Statistical analyses analyzing overall and disease-free survival rates were performed with Kaplan-Meier curves, χ2 analysis, and t test. For continuous variables, effect size was measured using Cohen d; a value of 0.2 indicates a small effect size, 0.5 a moderate effect size, and 0.8 a large effect size. For categorical variables with more than 2 subcategories, effect size was measured using Cramer V, which ranges from 0 to 1, and wherein a value of 0.1 indicates a small effect size, 0.3 indicates a moderate effect size, and 0.5 indicates a large effect size. For categorical variables with 2 subcategories, effect size was measured using an odds ratio (OR), where effect size is measured by distance away from the value 1, which indicates no effect. Analyses were performed using SPSS, version 28.0.1 (IBM).
Results
After exclusion criteria were applied, 170 patients were included in this study. The mean (SD) age of patients in the cohort was 61.8 (9.9) years, and 140 patients (82%) were male. The most common location for tumors was in the tonsil (n = 79 [47%]), followed closely by the base of tongue (n = 68 [40%]). Because advanced-staged tumors were excluded, 130 tumors (77%) were found to be pathologically staged T1, whereas 40 (23%) were found to be staged T2. Most patients (n = 121 [71%]) received some form of adjuvant therapy—the majority of patients received radiotherapy (n = 78 [46%]), but a notable portion received chemoradiotherapy (n = 43 [25%]). A considerable number of patients received no adjuvant therapy (n = 43 [25%]). Fifty percent of patients (n = 85) received a positive intraoperative control biopsy as a reference for margin analysis while the remaining half did not (n = 85). The clinical and demographic characteristics of study cohort are summarized in Table 1.
Table 1. Clinical and Demographic Characteristics of the Cohort (N = 170).
| Characteristic | Patients, No. (%) | No. (%) | Difference between groups with and without control biopsy, effect size (95% CI) | |
|---|---|---|---|---|
| Without biopsy (n = 85) | With biopsy (n = 85) | |||
| Age, mean (SD), y | 61.8 (9.9) | 63.6 (8.6) | 60.4 (10.8) | Cohen d, 0.33 (0.02-0.63) |
| Sex | ||||
| Female | 30 (18) | 19 (22) | 11 (13) | OR, 0.52 (0.23-1.17) |
| Male | 140 (82) | 66 (78) | 74 (87) | |
| Intraoperative frozen section control | ||||
| Yes | 85 (50) | 85 (100) | 85 (100) | NA |
| No | 85 (50) | 0 | 0 | |
| Tumor site | ||||
| Palatine tonsil | 79 (47) | 38 (45) | 41 (48) | Cramer V, 0.06 (0.02-0.23) |
| Glossopharyngeal sulcus | 23 (14) | 13 (15) | 10 (12) | |
| Base of tongue | 68 (40) | 34 (40) | 34 (40) | |
| Cancer stage on diagnosis | ||||
| I | 130 (77) | 65 (77) | 65 (77) | OR, 1.00 (0.49-2.03) |
| II | 40 (23) | 20 (24) | 20 (24) | |
| Primary TORS vs salvage surgery | ||||
| Primary | 158 (93) | 75 (88) | 83 (98) | OR, 0.18 (0.04-0.85) |
| Salvage | 12 (7) | 10 (12) | 2 (2) | |
| Tumors with positive to negative margin reversal on final pathology | ||||
| No | 158 (93) | 81 (95) | 77 (91) | OR, 2.10 (0.61-7.27) |
| Yes | 12 (7) | 4 (5) | 8 (9) | |
| Tumors with negative to positive margin reversal on final pathology | ||||
| No | 164 (97) | 95 (81) | 98 (83) | OR, 0.49 (0.09-2.74) |
| Yes | 3 (6) | 4 (5) | 2 (2) | |
| Tumors with intraoperative nondiagnostic margins requiring additional sampling | ||||
| No | 152 (89) | 77 (91) | 75 (88) | OR, 1.28 (0.48-3.43) |
| Yes | 18 (11) | 8 (9) | 10 (12) | |
| Ultimate intraoperative margin status | ||||
| Negative | 165 (97) | 80 (94) | 85 (100) | OR, 0.94 (0.89-0.99) |
| Positive | 5 (3) | 5 (6) | 0 | |
| Final margin status | ||||
| Negative | 160 (94) | 78 (92) | 82 (97) | OR, 0.41 (0.10-1.63) |
| Positive | 10 (6) | 7 (8) | 3 (3) | |
| Rounds of additional frozen sampling, mean (SD) | NA | 0.21 (0.47) | 0.28 (0.57) | Cohen d, 0.14 (0.00-0.44) |
| Post-TORS adjuvant therapy | ||||
| None | 43 (25) | 22 (26) | 21 (25) | Cramer V, 0.10 (0.03-0.27) |
| Radiotherapy | 78 (46) | 36 (42) | 42 (49) | |
| Chemoradiotherapy | 43 (25) | 25 (29) | 18 (21) | |
| Unknown | 6 (4) | 2 (2) | 4 (5) | |
| Developed locoregional recurrence | ||||
| No | 155 (91) | 75 (88) | 80 (94) | OR, 0.46 (0.17-1.30) |
| Yes | 15 (9) | 10 (12) | 5 (6) | |
| Developed distant metastases | ||||
| Yes | 7 (4) | 79 (93) | 84 (99) | OR, 0.16 (0.02-1.33) |
| No | 163 (96) | 6 (7) | 1 (1) | |
| Adult Comorbidity Evaluation score | ||||
| 2 | 134 (79) | 63 (74) | 71 (84) | OR, 0.57 (0.27-1.20) |
| 3 | 36 (21) | 22 (26) | 14 (16) | |
Abbreviations: NA, not applicable; OR, odds ratio; TORS, transoral robotic surgery.
Of the defined adverse pathologic events, nondiagnostic margins were most common, with 18 patients (11%) requiring additional margin sampling. Positive frozen margins that were negative on fixed sectioning occurred in 12 patients (7%), while negative to positive reversal occurred in 6 patients (3%). Regarding oncologic outcomes, locoregional recurrence occurred in 15 patients (9%), while distant metastases occurred in 17 patients (4%), which are also summarized in Table 1. Although patients were not selected to receive a control biopsy based on any clinical criteria, patients who received a biopsy tended to be younger at diagnosis (difference in age between the 2 groups, 3.18 [95% CI, 0.22-6.14] years), less likely to have received salvage surgery (OR, 0.18 [95% CI, 0.04-0.85]), and more likely to have negative margin status based on frozen margin analysis at the conclusion of the case (OR, 0.94 [95% CI, 0.89-0.99]), as summarized in Table 1.
Figure 1 displays sample histologic images of a negative margin (Figure 1A) and a positive margin (Figure 1B). Histologic slides demonstrating the appearance of a frozen section control and an instance of an atypical margin for which diagnosis was made clear on comparison with a corresponding frozen section control are also included for concept visualization in Figure 1C and D. As is evident in Figure 1D, monopolar cautery can cause atypical presentation of cells compared with the normal tissue architecture of Figure 1A. However, the example of tumor appearance in Figure 1C provides evidence that this cancer demonstrates a high mitotic index and tissue architecture disruption but does not appear morphologically similar to the crushed cells of Figure 1D.
Figure 1. Examples of Hematoxylin-Eosin–Stained Frozen Oropharyngeal Cancer Margins.
A, Negative frozen margin (original magnification ×10). B, Positive frozen margin (original magnification ×10). Black arrowheads indicate areas of tumor extension. C, Positive frozen control section (original magnification ×10). D, Atypical frozen margin for which diagnosis was made clear by comparison with the frozen control section in panel C (original magnification ×10). Final diagnosis for the margin in panel D was negative. Samples in panels A, C, and D were taken from the same patient, while the sample in panel B is included for reference regarding the appearance of a positive frozen margin.
The diagnostic value of intraoperative frozen margin analysis was evaluated. Overall accuracy was noted to be 94.1%, with sensitivity of 85.1%, specificity of 97.4%, positive likelihood ratio of 32.7, and negative likelihood ratio of 0.15, as summarized in Table 2. The diagnostic value of intraoperative margin sampling statistically significantly improved in patients with a frozen section control, primarily in the fact that frozen section controls appeared to confer increased sensitivity to intraoperative margin sampling. Specifically, patients who received a control biopsy experienced a sensitivity of 88.9%, while patients without a reference biopsy experienced a sensitivity of 82.8%; the confidence interval of this difference was 3.9% to 8.3%, indicating that sensitivity was statistically significantly improved by this technique. Moreover, frozen section controls were statistically significantly associated with improved diagnostic utility of a positive intraoperative margin, as the positive likelihood ratio increased from 29.6 to 37.0 (difference, 7.4 [95% CI, 5.0-9.8]), as seen in Table 2.
Table 2. Diagnostic Value of Frozen Intraoperative Margin Analysis.
| Measurement | Total cohort (95% CI) | Patients with frozen section control (95% CI) | Patients without frozen section control (95% CI) | Difference in diagnostic value (95% CI) |
|---|---|---|---|---|
| Accuracy, % | 94.1 (92.5 to 95.7) | 94.5 (92.4 to 96.7) | 93.6 (91.2 to 96.0) | 0.9 (0.6 to 1.3) |
| Sensitivity, % | 85.1 (74.9 to 95.3) | 88.9 (74.4 to 100) | 82.8 (69.0 to 96.5) | 6.1 (3.9 to 8.3) |
| Specificity, % | 97.4 (96.3 to 98.5) | 97.6 (96.2 to 99.1) | 97.2 (95.6 to 98.8) | 0.4 (0.2 to 0.6) |
| Likelihood ratio | ||||
| Positive | 32.7 (21.3 to 51.2) | 37.0 (19.9 to 70.5) | 29.6 (16.2 to 54.3) | 7.4 (5.03 to 9.77) |
| Negative | 0.2 (0.1 to 0.3) | 0.1 (0.03 to 0.4) | 0.2 (0.1 to 0.4) | −0.07 (−0.08 to −0.06) |
The association of a positive control with resource use in the whole cohort was studied. The use of a frozen section control was not associated with the need for additional margin sampling, length of time spent in the operating room, length of hospital stay, or margin reversals from frozen to fixed pathology (eTable in the Supplement). However, these outcomes were examined specifically for the patients who received nondiagnostic margins to investigate whether there was a subset of patients who might benefit from this technique. There was a statistically significant reduction in length of time needed in the operating room (difference, 64.7 minutes; Cohen d, 1.14 [95% CI, 0.12-2.14]), as displayed in Figure 2. Also examined were clinical characteristics associated with margin uncertainty. Tumor location, history of head and neck irradiation, prior head and neck cancer, tumor size, and TNM staging were investigated as potential contributors to adverse pathologic events; however, none were found to be statistically significantly associated with margin atypia (Table 3).
Figure 2. Effect of Positive Control in Patients With Atypical Margins.
The edges of the boxes represent the lower and upper quartiles of each data group, the bars represent the mean of the group, and the edges of the whiskers represent the lower and upper extremes of the data groups.
Table 3. Associations of Clinical Characteristics of Patients With Nondiagnostic Intraoperative Margins (N = 170).
| Characteristic | No. (%) | Difference between groups with and without nondiagnostic intraoperative margins, effect size (95% CI) | |
|---|---|---|---|
| Without unclear margins (n = 152) | With unclear margins (n = 18) | ||
| Age, mean (SD), y | 61.4 (9.9) | 64.4 (9.0) | Cohen d, 0.08 (0.00-1.01) |
| Sex | |||
| Male | 124 (82) | 16 (89) | OR, 0.55 (0.12-2.55) |
| Female | 28 (18) | 2 (11) | |
| Intraoperative frozen section control | |||
| Yes | 77 (51) | 8 (44) | OR, 1.28 (0.48-3.43) |
| No | 75 (49) | 10 (56) | |
| Tumor site | |||
| Palatine tonsil | 72 (47) | 7 (39) | Cramer V, 0.09 (0.02-0.28) |
| Glossopharyngeal sulcus | 19 (13) | 4 (22) | |
| Base of tongue | 61 (40) | 7 (39) | |
| Cancer stage on diagnosis | |||
| I | 119 (78) | 11 (61) | OR, 2.30 (0.83-6.38) |
| II | 33 (22) | 7 (39) | |
| Primary TORS vs salvage surgery | |||
| Primary | 142 (93) | 16 (89) | OR, 1.78 (0.36-8.83) |
| Salvage | 10 (7) | 2 (11) | |
| Tumors with positive to negative margin reversal on final pathology | |||
| No | 150 (99) | 8 (44) | OR, 93.75 (17.53-501.27) |
| Yes | 2 (1) | 10 (56) | |
| Tumors with negative to positive margin reversal on final pathology | |||
| No | 146 (96) | 18 (100) | OR, 0.96 (0.93-0.99) |
| Yes | 6 (4) | 0 | |
| Ultimate intraoperative margin status | |||
| Negative | 147 (97) | 18 (100) | OR, 0.97 (0.94-1.00) |
| Positive | 5 (3) | 0 | |
| Final margin status | |||
| Negative | 142 (93) | 18 (100) | OR, 0.93 (0.90-0.97) |
| Positive | 10 (7) | 0 | |
| Post-TORS adjuvant therapy | |||
| None | 37 (24) | 6 (33) | Cramer V, 0.08 (0.02-0.25) |
| Radiotherapy | 71 (47) | 7 (39) | |
| Chemoradiotherapy | 39 (26) | 4 (22) | |
| Developed locoregional recurrence | |||
| No | 139 (91) | 16 (89) | OR, 2.82 (0.82-9.73) |
| Yes | 13 (9) | 2 (11) | |
| Developed distant metastases | |||
| Yes | 147 (97) | 16 (89) | OR, 3.68 (0.66-20.50) |
| No | 5 (3) | 2 (11) | |
| Adult Comorbidity Evaluation score | |||
| 2 | 123 (93) | 29 (81) | OR, 2.70 (0.96-7.56) |
| 3 | 11 (8) | 7 (19) | |
Abbreviations: OR, odds ratio; TORS, transoral robotic surgery.
Discussion
Frozen intraoperative margin analysis is a widely used tool to ensure complete excision of tumors.9,10,28 However, several limitations exist with the technique, particularly within the head and neck region.15,23,24 Some of these difficulties, including tissue shrinkage, artifact from frozen sectioning, and difficulty in margin orientation, are universal across methods of head and neck tumor resection.23 In addition to these challenges, TORS ablations involve the use of monopolar cautery, which can often result in considerable tissue distortion.21,23,26 Indeed, in the present study, we found a statistically significant percentage of the cohort experienced adverse pathologic outcomes such as uncertain margins requiring further sampling or diagnosis reversal from frozen to final assessment. Yet, though TORS presents a unique set of challenges in pathologic margin analysis, few studies specifically examine diagnostic validity of intraoperative margin assessment for patients receiving this operation. This study presents, to our knowledge, the first investigation into rates of adverse pathologic outcomes and the clinical features that may predispose patients to diagnostic inaccuracies during TORS resections. Moreover, we investigate the novel use of intraoperative frozen section controls in TORS procedures and characterize the circumstances under which this technique improves pathologic diagnostic accuracy and optimizes operating room resource utilization.
In this investigation of the use of routinely sending frozen section controls, we found that while use of frozen section controls was not associated with either survival or pathologic outcomes in the full cohort, patients with atypical margins required less time in the operating room if a positive control was obtained. This association implies that a definitive pathologic diagnosis was achieved more rapidly with the ability to reference a frozen section control when assessing cellular atypia. Additionally, patients who received a frozen section control experienced a statistically significant improvement in sensitivity (82.8%-88.9%) and positive likelihood ratio relative to those without a control biopsy. This suggests that the presence of a positive section control improved not only speed, but also diagnostic precision.
Several studies have questioned the use of intraoperative biopsies, citing concerns with the burden of maintaining necessary operating room equipment and personnel, as well as added expense.28 Critics have stated that gross examination by surgeons and pathologists is often sufficient to determine whether margins have been adequately resected.29,30 In light of these criticisms, the suggestion to routinely biopsy tumors intraoperatively may seem extraneous. However, ultimately providing a frozen section control requires minimal additional cost or added operating room time, particularly when compared with the costs and resources of additional rounds of frozen sections or the consequences of diagnostic reversals. Given the ease and marginal expense with which this technique can be performed, its use is worthwhile to prevent prolonged operating room use, as well as reduce need for additional margin sampling.
Moreover, an outcome not measured in this study is the qualitative feedback routinely received from the pathologist teams when provided with frozen section controls. Pathologist colleagues have noted that oropharyngeal lymphoepithelial tissue is particularly susceptible to thermal distortion and crush injury. The resulting distortion of normal lymphoid elements may mimic HPV-associated squamous carcinoma because of the similarity of cell size and the absence of cytoplasmic differentiation. Even for experienced head and neck pathologists, availability of a frozen section of the primary tumor exhibiting similar artifacts can be very helpful in distinguishing small foci of lymphoid cells from carcinoma. This decreases the necessity for re-excision of additional tissue from the tumor bed. Even without the clinical benefits noted in the present analysis, the dramatic improvement in the subjective experience of the clinicians interpreting these challenging margins represents a meaningful benefit to this technique.
Limitations
Important limitations exist within this study. Specifically, the cohort of patients in whom the control biopsy was taken demonstrated considerable differences compared with those without a control biopsy, as they were younger and had decreased rates of salvage surgery. However, though there was a reported difference in age between the 2 groups, it was likely not clinically significant, as the mean age differed by 3 years. Additionally, it is possible that the overall improvements in margin assessments may have been associated with increased pathologist experience over time rather than with the use of positive controls. This concern is mitigated by the large and diverse group of pathologists performing the frozen section analysis of this study. Lastly, the negative financial effect of taking an extra frozen specimen was not evaluated in the current study; however, given the vast variability surrounding the surgical care of a heterogenous patient population, this financial analysis was deemed to be poorly generalizable to a broader audience.
Conclusions
In this cohort study, patients with HPV-16–positive OPSCC who underwent either primary or salvage TORS experienced pathological challenges during frozen intraoperative margin analysis. We investigated the benefit of providing a positive intraoperative control in expediting definitive frozen margin assessment and found that for patients with margin atypia, the presence of a frozen control reduced time spent in the operating room. Moreover, sensitivity of intraoperative margin analysis was statistically significantly improved by providing frozen section controls. Given the ease and utility of this practice, we recommend that TORS surgeons obtain a frozen section control at the beginning of cases for comparison in margin analysis to ensure time-efficient and accurate frozen margin assessment, particularly in patients with risk factors for atypical tissue architecture.
eTable. Effect of a positive control on OR resource use in full cohort
References
- 1.Chaturvedi AK, Engels EA, Pfeiffer RM, et al. Human papillomavirus and rising oropharyngeal cancer incidence in the United States. J Clin Oncol. 2011;29(32):4294-4301. doi: 10.1200/JCO.2011.36.4596 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Mahal BA, Catalano PJ, Haddad RI, et al. Incidence and demographic burden of HPV-associated oropharyngeal head and neck cancers in the United States. Cancer Epidemiol Biomarkers Prev. 2019;28(10):1660-1667. doi: 10.1158/1055-9965.EPI-19-0038 [DOI] [PubMed] [Google Scholar]
- 3.Liu H, Wang Y, Wu C, et al. Robotic compared with open operations for cancers of the head and neck: a systematic review and meta-analysis. Br J Oral Maxillofac Surg. 2019;57(10):967-976. doi: 10.1016/j.bjoms.2019.08.023 [DOI] [PubMed] [Google Scholar]
- 4.Weinstein GS, O’Malley BW Jr, Magnuson JS, et al. Transoral robotic surgery: a multicenter study to assess feasibility, safety, and surgical margins. Laryngoscope. 2012;122(8):1701-1707. doi: 10.1002/lary.23294 [DOI] [PubMed] [Google Scholar]
- 5.Geltzeiler M, Doerfler S, Turner M, et al. Transoral robotic surgery for management of cervical unknown primary squamous cell carcinoma: updates on efficacy, surgical technique and margin status. Oral Oncol. 2017;66:9-13. doi: 10.1016/j.oraloncology.2016.12.033 [DOI] [PubMed] [Google Scholar]
- 6.Hanna J, Morse E, Brauer PR, Judson B, Mehra S. Positive margin rates and predictors in transoral robotic surgery after federal approval: a national quality study. Head Neck. 2019;41(9):3064-3072. doi: 10.1002/hed.25792 [DOI] [PubMed] [Google Scholar]
- 7.Ettl T, El-Gindi A, Hautmann M, et al. Positive frozen section margins predict local recurrence in R0-resected squamous cell carcinoma of the head and neck. Oral Oncol. 2016;55:17-23. doi: 10.1016/j.oraloncology.2016.02.012 [DOI] [PubMed] [Google Scholar]
- 8.Baumeister P, Baumüller K, Harréus U, Reiter M, Welz C. Evaluation of margins in head and neck squamous cell carcinoma from the surgeon’s perspective. Head Neck. 2018;40(5):963-972. doi: 10.1002/hed.25061 [DOI] [PubMed] [Google Scholar]
- 9.Williams MD. Determining adequate margins in head and neck cancers: practice and continued challenges. Curr Oncol Rep. 2016;18(9):54. doi: 10.1007/s11912-016-0540-y [DOI] [PubMed] [Google Scholar]
- 10.Li MM, Puram SV, Silverman DA, Old MO, Rocco JW, Kang SY. Margin analysis in head and neck cancer: state of the art and future directions. Ann Surg Oncol. 2019;26(12):4070-4080. doi: 10.1245/s10434-019-07645-9 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Varvares MA, Poti S, Kenyon B, Christopher K, Walker RJ. Surgical margins and primary site resection in achieving local control in oral cancer resections. Laryngoscope. 2015;125(10):2298-2307. doi: 10.1002/lary.25397 [DOI] [PubMed] [Google Scholar]
- 12.Barroso EM, Aaboubout Y, van der Sar LC, et al. Performance of intraoperative assessment of resection margins in oral cancer surgery: a review of literature. Front Oncol. 2021;11:628297. doi: 10.3389/fonc.2021.628297 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Serinelli S, Bryant SM, Williams MPA, Marzouk M, Zaccarini DJ. Frozen-permanent section discrepancy rate in oral cavity and oropharyngeal squamous cell carcinoma. Head Neck Pathol. 2022;16(2):466-475. doi: 10.1007/s12105-021-01385-7 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Nayanar SK, M AK, I MK, Thavarool P SB, Thiagarajan S. Frozen section evaluation in head and neck oncosurgery: an initial experience in a tertiary cancer center. Turk Patoloji Derg. 2019;35(1):46-51. [DOI] [PubMed] [Google Scholar]
- 15.Chaturvedi P, Singh B, Nair S, et al. Utility of frozen section in assessment of margins and neck node metastases in patients undergoing surgery for carcinoma of the tongue. J Cancer Res Ther. 2012;8(suppl 1):S100-S105. [DOI] [PubMed] [Google Scholar]
- 16.Baddour HM Jr, Magliocca KR, Chen AY. The importance of margins in head and neck cancer. J Surg Oncol. 2016;113(3):248-255. doi: 10.1002/jso.24134 [DOI] [PubMed] [Google Scholar]
- 17.Layfield EM, Schmidt RL, Esebua M, Layfield LJ. Frozen section evaluation of margin status in primary squamous cell carcinomas of the head and neck: a correlation study of frozen section and final diagnoses. Head Neck Pathol. 2018;12(2):175-180. doi: 10.1007/s12105-017-0846-6 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Thomas Robbins K, Triantafyllou A, Suárez C, et al. Surgical margins in head and neck cancer: intra- and postoperative considerations. Auris Nasus Larynx. 2019;46(1):10-17. doi: 10.1016/j.anl.2018.08.011 [DOI] [PubMed] [Google Scholar]
- 19.Demir B, Incaz S, Uckuyulu EI, Oysu C. Accuracy of frozen section examination in oral cavity cancers. Ear Nose Throat J. Published online November 6, 2020. doi: 10.1177/0145561320967334 [DOI] [PubMed] [Google Scholar]
- 20.Aaboubout Y, Barroso EM, Algoe M, et al. Intraoperative assessment of resection margins in oral cavity cancer: this is the way. J Vis Exp. 2021;10(171). doi: 10.3791/62446 [DOI] [PubMed] [Google Scholar]
- 21.Smithers FAE, Haymerle G, Palme CE, et al. A prospective study of intraoperative assessment of mucosal squamous cell carcinoma margins in the head and neck. Head Neck. 2021;43(2):590-600. doi: 10.1002/hed.26517 [DOI] [PubMed] [Google Scholar]
- 22.Kakarala K, Faquin WC, Deschler DG. A comparison of histopathologic margin assessment after steel scalpel, monopolar electrosurgery, and ultrasonic scalpel glossectomy in a rat model. Laryngoscope. 2010;120(suppl 4):S155. doi: 10.1002/lary.21619 [DOI] [PubMed] [Google Scholar]
- 23.Weinstock YE, Alava I III, Dierks EJ. Pitfalls in determining head and neck surgical margins. Oral Maxillofac Surg Clin North Am. 2014;26(2):151-162. doi: 10.1016/j.coms.2014.01.003 [DOI] [PubMed] [Google Scholar]
- 24.Laury A. Challenges in head and neck pathology. Cancer Treat Res. 2018;174:87-101. doi: 10.1007/978-3-319-65421-8_6 [DOI] [PubMed] [Google Scholar]
- 25.Lawson G, Matar N, Remacle M, Jamart J, Bachy V. Transoral robotic surgery for the management of head and neck tumors: learning curve. Eur Arch Otorhinolaryngol. 2011;268(12):1795-1801. doi: 10.1007/s00405-011-1537-7 [DOI] [PubMed] [Google Scholar]
- 26.Tirelli G, Hinni ML, Fernández-Fernández MM, et al. Frozen sections and complete resection in oral cancer surgery. Oral Dis. 2019;25(5):1309-1317. doi: 10.1111/odi.13101 [DOI] [PubMed] [Google Scholar]
- 27.Bulbul MG, Zenga J, Tarabichi O, et al. Margin practices in oral cavity cancer resections: survey of American Head and Neck Society members. Laryngoscope. 2021;131(4):782-787. doi: 10.1002/lary.28976 [DOI] [PubMed] [Google Scholar]
- 28.Mannelli G, Comini LV, Piazza C. Surgical margins in oral squamous cell cancer: intraoperative evaluation and prognostic impact. Curr Opin Otolaryngol Head Neck Surg. 2019;27(2):98-103. doi: 10.1097/MOO.0000000000000516 [DOI] [PubMed] [Google Scholar]
- 29.Kubik MW, Sridharan S, Varvares MA, et al. Intraoperative margin assessment in head and neck cancer: a case of misuse and abuse? Head Neck Pathol. 2020;14(2):291-302. doi: 10.1007/s12105-019-01121-2 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.DiNardo LJ, Lin J, Karageorge LS, Powers CN. Accuracy, utility, and cost of frozen section margins in head and neck cancer surgery. Laryngoscope. 2000;110(10 pt 1):1773-1776. doi: 10.1097/00005537-200010000-00039 [DOI] [PubMed] [Google Scholar]
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Supplementary Materials
eTable. Effect of a positive control on OR resource use in full cohort
