Intraoperative Depth of Invasion Is Accurate in Early-Stage Oral Cavity Squamous Cell Carcinoma

The Depth of Invasion and Level IV Cervical Node Metastasis in Patients with Clinically N0 Tongue Cancer

BACKGROUND

The accurate indication for level IV dissection is crucial for preventing complications such as phrenic nerve damage and chylous fistulas in clinically N0 tongue cancer. Although the depth of invasion is an established independent risk factor for occult lymph node metastasis in tongue cancer, its relationship with level IV metastasis has not been evaluated. This study investigated the relationship between the depth of invasion and level IV nodal metastasis in clinically N0 tongue cancer.

METHODS

We retrospectively investigated clinical N0 patients who underwent glossectomy and level I-IV neck dissection. We examined lymph node metastasis, risk factors, and the relationship between depth of invasion and metastasis.

RESULTS

Our study included 58 patients, and no patient had isolated level IV metastasis. Additionally, there was no level IV metastasis in well-differentiated tumors. Tumor size, depth of invasion, differentiation, and perineural invasion were significantly associated with level IV neck metastasis. We found a critical tumor size of 2.5 cm and depth of invasion of 8 mm for level IV neck metastasis.

CONCLUSION

Based on our findings, we recommend that level IV dissection should be considered for poorly differentiated tumors, tumors greater than 2.5 cm in size, and those deeper than 8 mm. This study highlights the importance of depth of invasion as a prognostic factor for predicting level IV metastasis and suggests that our findings can be used to prevent unnecessary level IV dissections that may lead to complications in tongue cancer surgery.

WPOI-5: Accurately Identified at Intraoperative Consultation and Predictive of Occult Cervical Metastases

BACKGROUND

Frozen section analysis of oral cancer specimens is ideal for assessing margin distances and depth of invasion (DOI); the latter impacts intraoperative decisions regarding elective neck dissection (END). Here, we show that intraoperative determination of worst pattern of invasion (WPOI), specifically WPOI-5, has a high level of accuracy. This relates to our demonstration herein that WPOI-5 predicts occult cervical metastases (OCM) for pT1 oral squamous carcinoma (OSC).

METHODS

The presence of OCM was correlated with WPOI in 228 patients with primary T1/T2/cN0 OSC undergoing resection and END. Concordance between intraoperative and final pathology WPOI determination was assessed on 51 cases of OSC.

RESULTS

WPOI-5 predicts OCM in pT1 patients, compared with WPOI-4/WPOI-3 (p < 0.0001). Most pT1 WPOI-5 tumors had DOI of 4-5 mm (24/59 or 40.7%). Only two pT1 WPOI-5 tumors had DOI < 4 mm (3.0 and 3.5 mm). If END were performed in this pT1 cohort for all WPOI-5 OSC patients regardless of DOI, OR all OSC patients with DOI ≥ 4 mm regardless of WPOI, then no OCM would be missed (p = 0.017, 100% sensitivity, 29% specificity, 77% positive predictive value, 23% negative predictive value). With respect to intraoperative WPOI-5 determination, the accuracy, sensitivity, and specificity was 92.16, 73.33, and 100.0%, respectively.

CONCLUSIONS

DOI ≥ 4 mm is the dominant predictor of OCM. For the rare WPOI-5 OSC with DOI < 4 mm, it is reasonable to suggest that surgeons perform END. WPOI-5 may be accurately determined intraoperatively. As microscopic instruction is needed to accurately assess WPOI-5, a teaching link is included in this manuscript.

Ultrasound accurately assesses depth of invasion in T1‐T2 oral tongue cancer

Background

Depth of invasion (DOI) is important for the T‐classification of squamous cell carcinoma of the oral tongue (SCCOT) and incorporated in the TNM 8 classification of oral cavity cancer. To determine DOI clinical palpation is performed, but the preferred radiological modality remains controversial. The aim of this study was to investigate the assessment of DOI using ultrasound (US‐DOI).

Methods

The DOI was assessed in 40 patients with T1–T3 SCCOT by ultrasound, palpation, computed tomography and magnetic resonance imaging (MRI). Histopathological DOI (H‐DOI) was gold standard. Bland–Altman analysis was used to compare mean difference and 95% limits of agreement (LOA).

Results

The mean difference of US‐DOI was −0.5 mm (95% LOA −4.9–4.0) compared to H‐DOI and the mean difference for MRI was 3.9 mm (95% LOA −2.3–10.2). In the subgroup analysis of cT1‐T2 the US‐DOI mean difference was 0.1 mm and the 95% LOA limits −2.5–2.7.

Conclusions

Ultrasound seems to be the most accurate method to assess DOI in T1‐T2 SCCOT. MRI overestimates DOI and cannot assess a substantial proportion of the tumors.

Level of Evidence

2c.

The Potential of MET Immunoreactivity for Prediction of Lymph Node Metastasis in Early Oral Tongue Squamous Cell Carcinoma

Objective

MET positivity is independently associated with survival in oral squamous cell carcinoma (OSCC). Since MET is a known orchestrator of invasive tumor growth, we investigated its association with LNM in early oral tongue squamous cell carcinoma (OTSCC). As it is recommended by the NCCN to use tumor depth of invasion (DOI) in making decisions on elective neck dissection (END), the results obtained for MET positivity were aligned with those for DOI > 4 mm. The cutoff value used in our institution.

Methods

Tumor samples from patients who underwent primary tumor resection and neck dissection between 1995 and 2013, were collected from the archives of the Leiden and Erasmus University Medical Center. Immunohistochemistry with D1C2 was performed to identify MET negative (< 10% uniform positivity) and MET positive (≥ 10% uniform positivity) cancers. ROC curve analysis and the Chi-squared test were used to investigate the association of MET positivity with LNM (pN+ and occult). Binary logistic regression was used to investigate the association of MET positivity with LNM.

Results

Forty-five (44.1%) of the 102 cancers were MET positive. Ninety were cN0 of which 20 were pN+ (occult metastasis). The remaining 12 cancers were cN+, of which 10 were proven pN+ and 2 were pN0. MET positivity was associated with LNM with a positive predictive value (PPV) of 44.4% and a negative predictive value (NPV) of 82.5% for pN+. For the occult group, the PPV was 36.8% and the NPV was 88.5%. Regression analysis showed that MET positivity is associated with pN+ and occult LNM (p-value < 0.05).

Conclusion

MET positivity is significantly associated with LNM in early OTSCC, outperforming DOI. The added value of MET positivity could be in the preoperative setting when END is being considered during the initial surgery. For cases with DOI ≤ 4 mm, MET positivity could aid in the clinical decision whether regular follow-up, watchful waiting, or END is more appropriate. Realizing that these preliminary results need to be independently validated in a larger patient cohort, we believe that MET positivity could be of added value in the decision making on END in early OTSCC.

Research on neck dissection for oral squamous-cell carcinoma: a bibliometric analysis

Neck dissection for oral squamous-cell carcinoma (OSCC) is a clinically controversial issue and has therefore been the subject of abundant research. However, no one has performed a bibliometric study on this topic to date. The aim of this study was to assess the development of research on neck dissection for OSCC in terms of the historical evolution, current hotspots and future directions, particularly including research trends and frontiers from 2010 to 2019. Literature records related to research on neck dissection for OSCC were retrieved from the Web of Science Core Collection (WoSCC). CiteSpace was used as a tool to perform a bibliometric analysis of this topic. The survey included 2 096 papers. “Otorhinolaryngology” was the most popular research area. The most active institutions and countries were Memorial Sloan Kettering Cancer Center and the USA, respectively. Shah J.P. was the most cited author. Among the six identified “core journals”, Head & Neck ranked first. The top three trending keywords were ‘invasion’, ‘upper aerodigestive’ and ‘negative neck’. ‘D’Cruz AK (2015)’ was the most cited and the strongest burst reference in the last decade. The study evaluated the effect on survival of elective versus therapeutic neck dissection in patients with lateralized early-stage OSCC. The depth of invasion and the management of N0 OSCC were research frontiers in this field. The present study provides a comprehensive bibliometric analysis of research on neck dissection for OSCC, which will assist investigators in exploring potential research directions.

Comparison of Early Oral Cancer Depth of Invasion From the American Joint Committe on Cancer 7th to 8th Edition Criteria. Does the Difference Impact the Accuracy of Clinical Decision Making?

PURPOSE

Depth of invasion (DOI) is an independent predictor of regional metastasis in oral squamous cell carcinoma. Measurement criteria for DOI were modified in the American Joint Committee on Cancer (AJCC) eighth edition. The purpose of this study was to compare DOI AJCC seventh (DOI7) and eighth (DOI8) edition criteria on frozen section accuracy for decisions regarding elective neck dissection (END) in cT1N0 oral squamous cell carcinoma.

PATIENTS AND METHODS

A blinded, retrospective, comparative study of patients who underwent ablative surgery at the University of Michigan was completed. The predictor variable was criteria for DOI measurement. The outcome variables were concordance between DOI7 and DOI8 measurements and accuracy using thresholds for END. Effect of tumor growth pattern and worst pattern of invasion, and the difference between DOI8 on frozen and permanent specimen were assessed.

RESULTS

A total of 30 specimens of T1N0 oral squamous cell carcinoma (16 tongue, 5 alveolus, 5 floor of mouth, 4 buccal mucosa) were included. DOI7 versus DOI8 on frozen and permanent specimen were significantly different (P < .05) but clinically insignificant and highly correlated (r > 0.99, P < .001). One hundred percent concordance between DOI7 and DOI8 was noted on frozen specimen in predicting the need for END when compared with permanent pathology DOI. There was no significant impact of tumor growth pattern or worst pattern of invasion on measurements and no significant difference in DOI on frozen and permanent specimen for DOI8 (P = .68). Excellent agreement between pathologists for all measurements was observed (ICC>0.99, P < 0001).

CONCLUSIONS

High concordance between DOI measurements by AJCC seventh and eighth edition criteria suggests that guidelines for DOI thresholds for END in patients with T1N0 tumors developed using the AJCC seventh edition can be safely applied using AJCC eighth edition criteria. DOI measurement by AJCC 8 criteria on frozen specimen can be used to guide decision-making regarding END, given the high correlation to AJCC 8 permanent DOI measurement.

Is Perineural Invasion a Reasonable Indicator for Neck Dissection in cT1N0M0 Squamous Cell Carcinoma of the Oral Cavity?

PURPOSE

Perineural invasion (PNI) is considered an adverse histological feature in oral squamous cell carcinoma (OSCC). Controversy exists regarding elective neck dissection (END) in cT1N0M0 OSCC with PNI as the only risk factor. The purpose of this study was to evaluate PNI as an indicator for END, as well as its utility when combined with the depth of invasion (DOI) as a second indicator.

PATIENTS AND METHODS

cT1N0M0 (AJCC8) OSCC patients treated from August 1998 to July 2017 in the Department of Oral and Maxillofacial Surgery, University of Michigan (MI), and Beijing Stomatological Hospital, Capital Medical University (BSH) were reviewed. Data from these sites included both prospectively captured data housed in a database and retrospective data.

RESULTS

283 cT1N0M0 OSCC patients were analyzed. The tongue was the most common subsite (56.2%). Ninety-nine (99) patients received END and 184 neck observation. PNI was found in only 8 patients (2.83%) all in the tongue or inferior gingiva. END was performed in 7 of the PNI patients. The mean depth of invasion for tumors with PNI was 3.97 mm, compared to 2.54 mm in tumors without PNI. PNI was statistically correlated with nodal disease (pN+) and extranodal extension (ENE+). After using DOI as a primary indicator for END, no additional PNI patients benefited from END. In addition, only 2 patients had PNI identified preoperatively both with 5 mm DOI, and therefore, already indicated for END on the basis of DOI status.

CONCLUSIONS

PNI status is statistically correlated with pN+ and ENE + pathology in cT1N0M0 OSCC. After using DOI as a primary indicator for END, PNI status had no added value in decision making. Even surgeons who do not use DOI will find very limited value in PNI status with less than 1% preoperative prevalence (0.71%) in this patient population.

Elective Neck Dissection in T1N0M0 Oral Squamous Cell Carcinoma: When Is It Necessary?

PURPOSE

Elective neck dissection (END) versus observation remains controversial for cT1N0M0 oral cavity squamous cell carcinoma (OSCC). The aim of this study was to determine whether neck dissection is indicated for cT1N0M0 OSCC versus observation when considering oral cavity subsites and depth of invasion (DOI) as predictors.

PATIENTS AND METHODS

A multicenter, ambispective cohort study of patients with cT1N0M0 OSCC treated at the University of Michigan and Beijing Stomatological Hospital from August 1998 to July 2017 with a follow-up end date of July 2019 was performed. Patients were excluded if follow-up was less than 2 years and no neck disease had occurred or if the final pathologic analysis resulted in upstaging to T2 using American Joint Committee on Cancer criteria, eighth edition. A total of 283 patients met the criteria. The main outcome parameter was the 2-year neck metastatic rate.

RESULTS

The total 2-year lymph node metastatic rate was 11.3%. Overall neck metastatic rates escalated consistently according to DOI: less than 2 mm, 2.1%; 2 to 3 mm, 9.4%; 3 to 4 mm, 15.2%; and 4 to 5 mm, 24.6%. On univariate Cox regression analysis, DOI greater than 3 mm, tumor grade, and perineural invasion were statistically significant indicators of 2-year neck metastasis. On multivariate analysis, only DOI and tumor grade remained. On multivariate analysis of 2-year survival, no factors were independent predictors. Our proposed treatment strategy for END based both on statistically significant results for DOI and on review of the raw data using a 20% cutoff analysis showed cutoffs of 2 mm for the tongue (18.2%), 3 mm for the floor of the mouth (40.0%) and upper gingiva (20%), and 4 mm for the lower gingiva (33.3%) and no cutoff for the hard palate (0.0%).

CONCLUSIONS

The watch-and-wait approach remains a reasonable approach in selected patients with cT1N0M0 OSCC. Decision making for END in T1N0M0 patients should minimally consider tumor grade, DOI, and oral cavity subsite.