Can the inferior alveolar nerve be used as a marker in frozen section for free margin control after segmental mandibulectomy in tumour ablation?

A quantitative comparison of bone resection margin distances in virtual surgical planning versus histopathology: a prospective study

BACKGROUND

Positive bone margins have been shown to be associated with worse locoregional control and survival performance in oral oncology patients. With the application of computer-assisted surgery and patient-specific surgical guides, the authors can accurately execute the preoperative osteotomy plan. However, how well the authors can predict the margin distance in the final histopathology with a preoperative computed tomography (CT) scan, the factors associated with it, and how much leeway CT should spare when designing the osteotomy planes during virtual surgical planning (VSP) remain to be investigated.

MATERIALS AND METHODS

Patients from January 2021 to December 2022 with benign or malignant jaw tumors and with signs of bone marrow involvement in the preoperative CT scan in our center were prospectively recruited to the study. VSP and measurement of the closest margin distance in the CT scan were performed by the single team of surgeons. The resection specimen was processed, and the margin distances were measured by a dedicated senior pathologist with the knowledge of orientation of the osteotomy planes.

RESULTS

A total of 35 patients were recruited, with 21 malignant and 14 benign cases. Sixty-eight bone margins were quantitatively analyzed. No significant difference in margin distances measured from the CT scan and final histopathology was detected ( P =0.19), and there was a strong correlation between the two (r s =0.74, P <0.01). A considerable amount of variance was detected in the level of discrepancy between margin distances measured in the CT scan and final histopathology (overall SD=6.26 mm, malignancy SD=7.44 mm, benign SD=4.40 mm). No significant correlation existed between the two margin distances when only maxilla tumor margins were assessed ( P =0.16).

CONCLUSION

The bone margin distance in VSP is reliably correlated to the final pathological margin distance. A leeway distance of 15mm and 9mm should be considered when designing the osteotomy planes for malignancy and benign cases, respectively. Extra attention should be paid to maxilla cases when predetermining the osteotomy planes during VSP.

Surgical Margins in 3D Planned Mandibular Resections for Squamous Cell Carcinomas of the Oral Cavity

PURPOSE

Three-dimensional (3D) planned mandibular resections using cutting guides and preplanned plates are now widely used in oncological surgery. The main advantages are the gain of time, precision, and esthetic outcomes. The drawbacks include costs, time for planning, and printing the surgical tools. This time between the radiological data and the surgery may allow tumor progression, rendering the custom-made guides useless. There is no consensus regarding surgical margins that should be planned to ensure a safe oncologic outcome. The purpose of this retrospective study is to evaluate if the planned bony margins are adequate.

MATERIALS AND METHODS

Inclusion criteria were: Squamous cell carcinomas of the anterior and lateral floor of mouth with mandibular invasion (T4); mandibular resection using 3D planning and cutting guides. Between June 2015 to December 2019, 16 patients met the criteria. The time between the planning and the surgery was recorded. The authors decided to use a margin of at least 1 cm on the preoperative computerized tomography scans on each side of the tumors in our planning for all patients. The authors then measured the distance of the bone resection on the pathological specimen.

RESULTS

All 16 patients had safe bone surgical margins (R0). The average time from the scanners used for the planning to the surgery was 33 days.

DISCUSSION

All the cutting guides could be used. The pathology examination showed safe oncological margins and no patients required further resection. A 1 cm margin during 3D planning for mandibular resections with 3D printed cutting guides, in patients with T4 Squamous Cell Carcinomas can therefore be considered safe.

Prognostic Implications of Combined Imaging and Histologic Criteria in Squamous Cell Carcinoma with Mandibular Invasion

Prognosis prediction of squamous cell carcinoma (SCC) with mandibular invasion is controversial, and a more sophisticated staging system to aid prognosis could be developed with imaging characteristics of bone invasion. Imaging-feature analysis provides practical, stratified results for survival prognosis in oral SCC (OSCC) of the mandible, and imaging advances enable more detailed tumor visualization. We retrospectively evaluated significant bone-invasion features associated with poor outcomes in mandibular OSCC to assess the predictive value of staging criteria that combined imaging features and histologic grade (combined imaging–histology (IH) grade) in 65 patients (39 men, 26 women) with mandibular SCC diagnosed from 2006 to 2016. Clinicopathologic features, including T-stage and histologic grade, and prognosis were retrieved. Tumors were classified into three types by extent of mandibular invasion on pretreatment imaging studies. Moreover, we assessed the involvement of the mandibular canal. We examined the correlation of factors associated with locoregional recurrence and overall mortality. The Harrell Concordance Index (C-index) determined prognostic performance of predictors. Nineteen (29%) patients showed locoregional recurrence and 13 (20%) died. For locoregional recurrence and mortality rates, imaging-detected mandibular canal (MC) involvement is a stronger prognostic factor for recurrence (C-index = 0.61 > 0.58) and survival (C-index = 0.58 > 0.63) than histopathologically confirmed perineural invasion, as was the IH grade, especially IH Grade 3, which was significantly associated with worse locoregional recurrence (p < 0.02). Imaging-based staging showed higher prognostic performance than T-staging (C-index = 0.57 (recurrence), 0.60 (death)), when combined with histologic grading (C-index = 0.69 for both) or used alone (C-index = 0.63 (locoregional recurrence), 0.69 (death)). Overall survival was significantly stratified by Imaging type and IH grade. Therefore, analysis of imaging features provided more specific, practical results for survival prognosis in mandibular OSCC. Imaging advances can potentially provide detailed gross views of tumor masses to facilitate development of prognostic criteria for OSCC.

Intraoperative cytological examination of bone medullary. A useful technique to predict the extension of bone invasion in segmental mandibulectomy

AIM

The main of the present report is to evaluate the utility of intraoperative cytological analysis of medullary bone to predict the extension of bone infiltration in segmental mandibulectomy.

MATERIALS AND METHOD

Between the years 2016 and 2018, a total of 17 previously untreated patients with squamous cell carcinoma of the oral cavity underwent a segmental mandibular resection and intraoperative cytological analysis of the bone medullary at Virgen de las Nieves University Hospital (HUVN). The results of the intraoperative cytological analysis were compared with the result of the postoperative histopathological examination and sensitivity, specificity, positive predictive value, and negative predictive value of the test were calculated.

RESULTS

Cytological analysis was positive in three patients and the bone resection was consequently extended. All the extensions of these bone margins were clean following the postoperative histological examination. However, two other patients previously classified as clean with intraoperative cytological analysis of bone medullary presented infiltration of bone margins postoperatively. The protocol demonstrated a high negative predictive value (85,7%). The positive predictive value, sensitivity, and specificity were 33,3%, 33,3%, and 85,7% respectively.

CONCLUSION

Intraoperative cytological analysis of bone medullary could represent an easy, fast, reliable and inexpensive method to reduce the rate of r1 surgeries attributable to the infiltration of the bone margin. This may have a positive impact on overall survival without increasing the duration and the iatrogenicity of surgery.

What Is a Safe Distance for Preservation of the Inferior Alveolar Nerve in Lower Gingival Squamous Cell Carcinoma? A Radiographic and Histopathological Study

PURPOSE

Involvement of the inferior alveolar nerve (IAN) is important in the prognosis and treatment of gingival squamous cell carcinoma (SCC).

METHODS

In this cross sectional study, patients with gingival SCC (T4a), undergoing hemimandibulectomy or subtotal hemimandibulectomy, were examined. The distance between the lesion and inferior alveolar canal (IAC) was measured, using axial computed tomography scans before resection. Following that, histopathological evaluation of IAN was conducted. The receiver operating characteristic curve was plotted to determine the association of IAN involvement in histopathological evaluation with various distances between the lesion and IAC.

RESULTS

A total of 29 patients were examined in this study. The mean distance between the lesion and IAC was 9.40 ± 2.21 mm. Nerve involvement was documented in 9 (45%) out of 20 males, while 11 (55%) men showed no involvement. Thirteen (44.82%) patients showed IAN involvement. The receiver operating characteristic curve demonstrated a cut-off point of 9.75 mm for the lesion-IAN distance. The possibility of IAN involvement was 23.33 times higher in patients who reported paresthesia, compared with patients without nerve involvement (odds ratio, 23.33; 95% CL; P = 0.001) CONCLUSION:: It seems that in a CT scan view, a 9.75-mm safe margin is associated with high accuracy for preserving IAN in patients with gingival SCC. Also, neurosensory disturbance can be considered a strong predictor of IAN involvement.

Guidelines for the Surgical Management of Oral Cancer: Korean Society of Thyroid-Head and Neck Surgery

Korean Society of Thyroid-Head and Neck Surgery appointed a Task Force to provide guidance on the implementation of a surgical treatment of oral cancer. MEDLINE databases were searched for articles on subjects related to “surgical management of oral cancer” published in English. Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. The quality of evidence was rated with use RoBANS (Risk of Bias Assessment Tool for Nonrandomized Studies) and AMSTAR (A Measurement Tool to Assess the Methodological Quality of Systematic Reviews). Evidence-based recommendations for practice were ranked according to the American College of Physicians grading system. Additional directives are provided as expert opinions and Delphi questionnaire when insufficient evidence existed. The Committee developed 68 evidence-based recommendations in 34 categories intended to assist clinicians and patients and counselors, and health policy-makers. Proper surgical treatment selection for oral cancer, which is directed by patient- and subsite-specific factors, remains the greatest predictor of successful treatment outcomes. These guidelines are intended for use in conjunction with the individual patient’s treatment goals.

Development of a Rapid Analysis Method for Bone Resection Margins for Oral Squamous Cell Carcinoma by Immunoblotting

The purpose of this proof-of-principle study was to develop a rapid and approachable method to analyse bone resection margins in patients with oral squamous cell carcinoma (OSCC) in an intraoperative setting, similar to assessing frozen sections of soft tissue. Bone excision and risk of remaining tumour cells could be minimised, thus improving reconstruction measures and facilitating convalescence. Frozen, sawed wafers of porcine bone artificially combined with porcine skin (simulating OSCC properties) were used to develop and evaluate a new molecular method: protein transfer from non-decalcified, sawed wafers onto a membrane stained by immunofluorescence (Tissue-ProtTrans). Tissue-ProtTrans was based on the detection of keratin 5/6 as a marker of tumour cells. The results were compared to standard immunohistochemistry (IHC) and H&E results of the same wafers after decalcification. Tissue-ProtTrans resulted in a total assay time of 3.5 h using the Trans-Blot® Turbo™ Transfer System (Bio-Rad) for protein transfer. Amersham Protran® Premium Nitrocellulose Membranes 0.2 µm (GE Healthcare) were stained with a primary antibody to keratin 5/6 (Dako Agilent) and a secondary antibody labelled with IRDye® 800CW (LI-COR). Visualisation was performed with an infrared laser scanner (Odyssey). Upon comparison, five independent experiments on porcine specimens processed with the Tissue-ProtTrans showed similar results to standard IHC and H&E analysis. In comparison to standard IHC results (requiring several days due to decalcification) Tissue-ProtTrans provided similar results, but was much faster (3.5 h). This highly promising method has good potential for further time reduction and will be suitable for intraoperative assessment.