Preoperative assessment for and outcomes of mandibular conservation surgery

Risk factors for local recurrence following marginal mandibulectomy in gingival cancer

Surgery is the first line of treatment in gingival cancers of the mandible, and bone resection is necessary in the majority of cases. In the less extensive surgical option, marginal mandibulectomy (MM), the mandibular base is preserved. In contrast, in a segmental mandibulectomy (SM) the mandible is divided and the continuity is not preserved. If MM can be performed with comparable oncological results to SM, it is the preferred method. The aim of the present study was to identify preoperative predictors for local recurrence (LR), to support the selection of candidates for MM. Outcome measures were local recurrence free survival (LRFS) and disease specific survival (DSS). 67 patients treated with MM between 2008 and 2021 were included. Cox regression analyses of LR with hazard ratios and adjustments for postoperative radiotherapy, pathological T-stage (pT) and soft tissue margins were performed. 5-years LRFS was 63% (95% CI 46.9-75.5) and DSS 80.6% (95% CI 64.7-89.9). In conclusion we found that edentulous patients, more advanced pT-stage and positive soft tissue margins had increased risk for LR. Future studies of the correlation between cT and pT would be important to provide more robust preoperative support in the selection between MM and SM.

Evaluation of outcomes after conservative mandibular surgery in patients with oral squamous cell carcinoma

This study aimed to assess preoperative radiological and clinical examinations for identifying bone status and to evaluate survival outcomes in patients undergoing marginal mandibulectomy for the primary treatment of oral squamous cell carcinoma. The medical records, enhanced computed tomography (CT) scans, and pathological specimens of these patients were reviewed. Disease-free (DFS), local recurrence-free (LRFS), and osteoradionecrosis-free (ORNFS) survival were analysed. The study included 104 patients. The preoperative CT and clinical examinations achieved a sensitivity of 45.8% and specificity of 100% for judging bone condition. LRFS was 79.6% and DFS was 68.8%. Pathological bone invasion in significantly affected DFS (P = 0.597), while DFS was significantly higher for those with a lower clinical tumour stage (1/2 vs 3/4; P = 0.005) and postoperative radiotherapy (P = 0.011). Among 39 patients receiving postoperative radiotherapy, ORNFS was 75.2%. Postoperative chemotherapy significantly decreased ORNFS (P = 0.009). Tumour subsite (P = 0.003) and the resection site (P = 0.035) significantly affected the remaining bone height. The results indicate that CT and clinical examinations cannot precisely identify superficial bone damage, but work well in selecting patients for marginal resection. Adhering to current indications, this resection approach can guarantee safe bone margins in terms of survival outcomes.

Marginal versus Segmental Mandibulectomy in the Treatment of Oral Cavity Cancer: A Systematic Review and Meta-analysis

Introduction  Oral cavity squamous cell carcinoma (OCSCC) is the most common malignancy in the oral cavity. Two types of mandibular resections have been described: the segmental mandibulectomy and the marginal mandibulectomy. Both may have a different impact over the quality of life, oncological prognosis, and functional or aesthetic result. Objectives  The aim of this study was to systematically explore the literature to determine the survival outcomes and disease control rates in patients who underwent segmental or marginal mandibulectomy for OCSCC with histological evidence of cortical and medullary bone invasion. Data Synthesis  This review involved a systematic search of the electronic databases MEDLINE/PUBMED, Google Scholar, Ovid Medline, Embase, and Scopus including articles from 1985 to 2019. Fifteen articles were included for qualitative analysis and 11 articles were considered for meta-analysis calculations. All of them correspond to retrospective cohort studies. Conclusion  This systematic review reveals the low-level evidence regarding the impact over local control or survival according to the type of mandibulectomy. Our results need to be considered with precaution according to the limited evidence available. We just found difference regarding the 5-year disease-free survival, and a tendency in favor of segmental mandibulectomy was confirmed when medullary invasion was evident.

Oral squamous carcinoma: Aggressive tumor pattern of invasion predicts direct mandible invasion

BACKGROUND

Aggressive histologic worst pattern of invasion (WPOI) in surrounding soft tissue has been shown to be predictive of higher local recurrence and poorer survival in oral cavity squamous cell carcinoma (OCSCC) patients. This study investigates whether aggressive WPOI can predict the mandibular invasion phenotype.

METHODS

Patients consecutively diagnosed with OCSCC undergoing a mandibulectomy (marginal or segmental) between 2013 and 2018 were reviewed. Senior physicians re-reviewed radiologic scans and pathologic slides of 44 cases.

RESULTS

Aggressive WPOI (WPOI-4, 5) is significantly associated with infiltrative bone invasion. Non-aggressive WPOI (WPOI-1, 2, 3) is significantly associated with the absence of bone invasion.

CONCLUSIONS

WPOI has become a useful tool that further characterizes the biologic behavior of OCSCC. Potentially, planned surgery may escalate from a marginal to segmental mandibulectomy based on aggressive WPOI for patients with radiographically uncertain cortical status. Further studies are needed to validate the relationship between OCSCC WPOI and mandible status.

Oncologic outcome of marginal mandibulectomy in squamous cell carcinoma of the lower gingiva

Background

There is a large amount of controversy about the best management of the mandible in oral squamous cell carcinoma (SCC), mainly owing to the inability to acquire accurate bone invasion status. Therefore, our goal was to analyse the oncologic safety in patients undergoing marginal mandibulectomy (MM) for cT1-2 N0 SCC of the lower gingiva.

Methods

Patients undergoing MM for untreated cT1-2 N0 SCC of the lower gingiva were retrospectively enrolled. The main endpoints of interest were locoregional control (LRC) and disease-specific survival (DSS).

Results

A total of 142 patients were included in the analysis, and a pathologic positive node was noted in 27 patients. Cortical invasion was reported in 23 patients, and medullary invasion was reported in 9 patients. The 5-year LRC and DSS rates were 85 and 88%, respectively. Patients with bone invasion had a significantly higher risk for recurrence than patients without bone invasion. However, the DSS was similar in patients with versus without bone invasion. Patients with a high neutrophil lymphocyte ratio had a higher risk for worse prognosis.

Conclusions

The oncologic outcome in patients undergoing MM for cT1-2 N0 SCC of the lower gingiva was favourable; bone invasion was not uncommon, but it significantly decreased the prognosis in patients undergoing MM.

Marginal or segmental mandibulectomy: treatment modality selection for oral cancer: a systematic review and meta-analysis

Surgery is the most well established mode of initial definitive treatment for the majority of oral cancers. The most important decision in terms of tumour ablation in oral cancers when the jaws are potentially involved is the management of the mandible. The aim of this study was to explore the differences in survival rate and disease control between patients undergoing marginal mandibulectomy and patients undergoing segmental mandibulectomy using a systematic review and meta-analysis approach. A total of 15 cohort studies, including 1672 participants, were identified. Meta-analysis provided weak evidence in favour of segmental mandibulectomy for local control. Segmental mandibulectomy gave 73% better disease-free survival than marginal mandibulectomy when the marrow was invaded (P=0.04). The overall survival rate was evaluated, and no statistically significant difference was found between the two different mandibulectomy approaches, although the results showed a trend in favour of segmental mandibulectomy which could increase the overall survival by 23%. Based on these findings regarding the survival rate and efficacy of disease control, this study indicates that a marginal mandibulectomy may be recommended for cases with no invasion or superficial invasion of the mandibular cortex, and a segmental mandibulectomy may be a more reasonable choice for patients with extensive mandibular cortex invasion or medullary invasion.

Does Medullary Versus Cortical Invasion of the Mandible Affect Prognosis in Patients With Oral Squamous Cell Carcinoma?

PURPOSE

Whether mandibular involvement by oral squamous cell carcinoma (OSCC) could be identified as a factor for cancer staging and prognosis prediction remains a subject of debate. In addition, the influence of different types of mandibular invasion (cortical or medullary invasion) on patients' prognosis remains unclear. The aim of this systematic review was to establish whether mandibular invasion or its subset should be considered an independent prognostic factor for patients with OSCC.

MATERIALS AND METHODS

The search for eligible studies was performed according to the predesigned inclusion criteria for a systematic review. Mandibular invasion and invasion depth were considered the primary and secondary predictor variables, respectively. The electronic search was performed using 12 databases. Manual searching covered 14 related journals and references of the included studies were scanned. The risk of bias assessment was evaluated by 2 reviewers using risk-of-bias assessment tools recommended by Saltaji et al (Angle Orthod 82:1115, 2012). Two reviewers extracted the data in duplicate. RevMan 5.2 was used for meta-analysis to assess the primary outcomes (disease-free survival and overall survival) and the secondary outcomes (2- and 5-year survival rate and local control).

RESULTS

Eighteen studies (total, 3,756 participants) were included and used as the study sample. Among these included studies, 7 had an unclear risk of bias and the remaining showed a high risk. The results of the meta-analyses showed a significant relation between mandibular invasion and overall survival (P = .04) and, most importantly, that medullary involvement (P = .0001), but not cortical involvement (P = .66), could decrease overall survival. When focusing on disease-specific survival, mandibular medullary involvement predicted a poor disease-specific survival (P < .0001), but cortical involvement showed no effect (P = .66).

CONCLUSION

This review showed that OSCC mandibular medullary invasion, and not mandibular invasion or mandibular cortical invasion, could be an independent prognostic factor for patients.

Impact of mandibular condyle preservation on patterns of failure in head and neck cancer

Objective

To determine the role of native condyle preservation in local recurrence after segmental mandibulectomy in patients with head and neck squamous cell carcinoma.

Methods

Retrospective chart review with main outcome measuring local control of cancer.

Results

Between 1994 and 2003, 72 patients (48 men, 24 women) with an average age of 73.5 years without previous treatment underwent segmental mandibulectomy. Fifty-four cases (n = 54) involved the mandible posterior to the mental foramen and are the subject of this review. In 36 patients, the condyle was preserved and mandibular continuity was restored. In 18 patients, condyle and ramus were resected without mandibular reconstruction. Reconstructive modalities included primary closure (3), split-thickness skin graft (3), pedicle flap (19), and free tissue reconstructions (29). Overall local-regional recurrence rate was 22 percent (12 of 54); no recurrences were identified in patients who underwent condylar resection. Recurrences were observed in patients with mandibular reconstruction by both plate and pedicle flap (5 of 9) or (osteo) myocutaneous free flap (7 of 27).

Conclusion

Condylar preservation may predispose patients to local recurrence after segmental mandibulectomy. This does not translate into overall reduction in survival.

Retromolar trigone squamous cell carcinoma treated with radiotherapy alone or combined with surgery: a 10-year update

PURPOSE/OBJECTIVES

Treatment outcomes were analyzed for patients who received radiotherapy for squamous cell carcinoma of the retromolar trigone at a single institution.

MATERIALS/METHODS

We reviewed the medical records of 110 patients treated with radiotherapy alone (n=36) or radiotherapy combined with surgical resection of the primary tumor (n=74) between June 1966 and October 2013. The median follow-up was 4.5years for all patients and 11.8years for living patients (range, 1.3-23.5years).

RESULTS

The 5-year local-regional control rates after definitive radiotherapy versus surgery and radiotherapy for stages I-III were 52% and 89% and for stage IV they were 46% and 58%, respectively. The 5-year cause-specific survival rates after definitive radiotherapy compared with surgery and radiotherapy for stages I-III were 57% and 82% and for stage IV they were 45% and 43%, respectively. Multivariate analyses revealed that the likelihood of cure was better with surgery and radiotherapy compared with radiotherapy alone (p=0.041).

CONCLUSION

Patients treated with surgery and radiotherapy had a better chance of cure than those treated with radiotherapy alone. Complications of treatment were common in both groups but more common in patients who underwent surgery.

Mandibular conservation in oral cancer

Surgery is one of the established modes of initial definitive treatment for a majority of oral cancers. Invasion of bony or cartilaginous structures by advanced upper aero-digestive tract cancer has been considered an indication for primary surgery on the basis of historic experience of poor responsiveness to radiation therapy [1]. The mandible is a key structure both in the pathology of intra-oral tumours and their surgical management. It bars easy surgical access to the oral cavity, yet maintaining its integrity is vital for function and cosmesis. Management of tumours that involve or abut the mandible requires specific understanding of the pattern of spread and routes of tumour invasion into the mandible. This facilitates the employment of mandibular sparing approaches like marginal mandibulectomy and mandibulotomy, as opposed to segmental or hemimandibulectomy which causes severe functional problems, as the mandibular continuity is lost. Accurate preoperative assessment that combines clinical examination and imaging along with the understanding of the pattern of spread and routes of invasion is essential in deciding the appropriate level and extent of mandibular resection in oral squamous cell carcinoma. Studies have shown that local control rates achieved with marginal mandibulectomy are comparable with that of segmental mandibulectomy. In carefully selected patients, marginal mandibulectomy is an oncologically safe procedure to achieve good local control and provides a better quality of life. This article aims to review the mechanism of spread, evaluation and prognosis of mandibular invasion, various techniques and role of mandibular conservation in oral squamous cell carcinoma.

Prognostic impact of marginal mandibulectomy in the presence of superficial bone invasion and the nononcologic outcome

BACKGROUND

Treatment of oral cavity cancer may require variable extent of mandibular resection. Marginal mandibulectomy is a controversial technique in providing oncologic resection margin. This study analyzes the efficacy of local oncologic control and the morbidity of marginal mandibulectomy in oral cavity carcinoma. Nononcologic complication of osteoradionecrosis is discussed.

METHODS

A retrospective cohort study analyzed clinicopathologic features of 43 patients with oral cavity cancer who underwent marginal mandibulectomy. Histologic mandibular invasion was examined as a function of local control and contribution to osteoradionecrosis.

RESULTS

Bone invasion was present in 16.3% of patients with marginal mandibulectomy. Local control rates were 85.7% in the bone invasion group and 77.8% in the no bone invasion group (p = .7). Osteoradionecrosis rates were 16.7% and 17.6%, respectively (p = .96). There was no significant difference between the 2 groups.

CONCLUSIONS

Marginal mandibulectomy is oncologically sound in providing a safe resection margin in oral cavity cancer abutting or superficially invading the mandible.

Contemporary management of cancer of the oral cavity

Oral cancer represents a common entity comprising a third of all head and neck malignant tumors. The options for curative treatment of oral cavity cancer have not changed significantly in the last three decades; however, the work up, the approach to surveillance, and the options for reconstruction have evolved significantly. Because of the profound functional and cosmetic importance of the oral cavity, management of oral cavity cancers requires a thorough understanding of disease progression, approaches to management and options for reconstruction. The purpose of this review is to discuss the most current management options for oral cavity cancers.

Histopathological prognosticators in oral and oropharyngeal squamous cell carcinoma

Histopathological assessment of the surgical resection specimen continues to provide information that is central to determining the post-operative treatment needs and prognosis for an individual patient with oral/oropharyngeal squamous cell carcinoma. This review describes the prognostic value of histopathological features related to the primary tumour and the cervical lymph nodes, and considers their relative merits. In addition, a brief overview of more general patient factors is included. Throughout the review, guidance is offered on practical aspects of the histopathological assessment together with brief mention of potential inaccuracies. Emphasis is given also to the importance of the partnership between the surgeon and the pathologist, the need for standardisation during all stages of the histopathological assessment, and the value of accurate documentation of the findings.

Management of mandibular invasion: When is a marginal mandibulectomy appropriate?

There has been a great deal of controversy regarding the appropriate method of management of oral cavity and oropharyngeal tumors that invade the mandible. The inability to acquire intraoperative bone margins can make the decision process complex. Preoperative imaging offers several advantages, however, there is no single modality that has proven accurate. Intraoperative assessment has been suggested as a method of evaluation, however, this approach does not allow for preoperative planning. The following is a review of the current literature regarding mandibular invasion and the indications for a marginal mandibulectomy.

Influence of marginal and segmental mandibular resection on the survival rate in patients with squamous cell carcinoma of the inferior parts of the oral cavity

AIM

The aim of this retrospective study was to investigate whether radical (segmental resection) or conservative (marginal) resection of mandibular bone influenced patients, survival.

PATIENTS AND METHODS

A series of 136 patients selected for partial mandibular resection for the treatment of squamous cell carcinomas of the lower oral cavity was evaluated retrospectively. Fifty-four patients underwent marginal and 82 cases segmental resection of the mandible. The mean follow-up periods were 91.1+/-30.1 months and 91.5+/-26.2 months, respectively. Data was extracted from the patient records and transferred into a database for statistical evaluation. Results Mean survival was 63.0+/-35.3 months for marginal and 53.1+/-32.3 months for segmental resection. The overall survival rate was analysed according to Kaplan-Meier and the test of significance (Log Rank) which yielded no statistically significant difference in the survival rate between both groups (p=0.1119). Numbers of recurrences, second primaries, metastases and/or postoperative complications were similar in both groups, i.e. no statistically significant differences were observed (ANOVA, Post-hoc Scheffé test). Conclusion In cases with an indication for bone resection, marginal resection may achieve satisfactory control and is as effective as segmental resection.

The influence of the pattern of mandibular invasion on recurrence and survival in oral squamous cell carcinoma

BACKGROUND

Controversy exists over the predictive value of the presence and pattern of tumor invasion of the mandible in oral squamous cell carcinoma (SCC). Many authors have questioned increasing the classification of small tumors to T4 on the basis of mandibular invasion alone. There are little data on the influence of the pattern of invasion on prognosis.

METHODS

We prospectively reviewed 100 consecutive mandibular resections for previously untreated oral SCC. Clinical and pathologic data collected included details of soft and hard tissue histologic findings. Outcomes included recurrence (local, regional, and distant metastases), disease-specific survival, and death from other causes. The median follow-up for survivors was 65 months.

RESULTS

Of 100 cases, 65 involved segmental and 35 involved marginal resections. Sixty-two percent of mandibles were invaded by tumor. Local recurrence occurred in 21% and was strongly correlated with tumor size, nodal involvement, and pattern of soft tissue invasion. The 5-year disease-specific survival was 68%, and the crude survival was 50%. Mandibular invasion predicted for recurrence and disease-specific survival, even after correcting for the effects of other variables. The pattern of mandibular invasion (erosive/infiltrative) was also predicted for recurrence and disease-specific survival.

CONCLUSIONS

Even in the presence of mandibular invasion, soft tissue factors are the most important determinants of prognosis. Upstaging tumors on the basis of mandibular invasion is justified. An infiltrative pattern of bone invasion is a marker of aggressive tumor biology and should be included in the pTNM classification.

Marginal mandibulectomy for lateral sulcus tumours

OBJECTIVE

To report a retrospective series of marginal mandibulectomy for cancers of oral cavity, with special reference to squamous cancers of gingival buccal complex.

METHODS

Retrospective record review of 107 patients who underwent marginal mandibulectomy between 1994 and 2001.

RESULTS

Eighty-three marginal mandibulectomies were done for gingivo-buccal complex cancers. Local failure rate was 16%. The 2-year and 5-year disease free survival rates were 69 and 60%, respectively. The local recurrence free survival at the end of 2 and 5 years were 79 and 70%, respectively.

CONCLUSION

In carefully selected patients, marginal mandibulectomy is an oncologically safe procedure to achieve good local control.

Posterior Marginal Mandibulectomy in the Management of Cancer of the Oral Cavity and Oropharynx

OBJECTIVE: To review a single institution's experience with posterior marginal (ramus) mandibulectomy for mandibular preservation in the management of patients with squamous cell carcinoma of the retromolar trigone or oropharynx. To review the history and surgical technique with emphasis on functional as well as oncologic outcomes.

STUDY DESIGN AND SETTING: Retrospective review at a tertiary care academic referral center from 1996 to 2002.

RESULTS: Between 1996 and 2002, 382 patients with squamous cell carcinoma of the oral cavity and oropharynx were surgically treated at the Loyola University Medical Center. Medical records were reviewed and 152 patients were identified who had some form of mandibular procedure (segmental resection, marginal resection, or mandibulotomy) performed in conjunction with their tumor resection. Eighteen posterior marginal mandibulectomies were performed for primary cancers of the retromolar trigone, tonsillar fossa, and/or base of the tongue. All patients received adjuvant radiotherapy. Bone invasion of the marginal mandibulectomy specimens by squamous cell carcinoma was observed in 2 cases, neither of which developed a local recurrence. Mean and median overall survivals were 41.4 and 37.5 months, respectively. Functional outcomes were determined by administering the University of Washington Quality of Life instrument administered at 12 months. Patients reported significant alterations in chewing, but all were able to maintain satisfactory oral intake and no patient required a gastrosotomy tube.

CONCLUSIONS: A posterior osteotomy of the mandibular ramus is a useful adjunct in the surgical treatment of cancer of the retromolar trigone or oropharynx. Negative surgical margins can be obtained even with focal invasion of mandibular bone. The loss of bone in this area does not significantly affect patients' appearance. Patients report deterioration in chewing following this procedure but are able to maintain a diet of solid food. (Otolaryngol Head Neck Surg 2003;129:713-9.)

Marginal and segmental mandibulectomy in patients with oral cancer: a statistical analysis of 106 cases

PURPOSE

The treatment of oral squamous cell carcinoma may require mandibular resection to secure adequate margin. This bone resection often is segmental or marginal mandibulectomy. The purpose of this work was to evaluate the local control and survival after surgical treatment of oral cancer, according to these 2 different mandibular resection procedures.

PATIENTS AND METHODS

We conducted a retrospective study of a 20-year cohort of 106 patients who underwent marginal or segmental mandibulectomy for oral cancer. All patients had a biopsy-confirmed diagnosis of squamous cell carcinoma involving either the floor of the mouth, mandibular gingiva, retromolar trigone, tongue, buccal mucosa, or oropharynx. The type of mandibular resection and treatment outcome were compared, using an univariate analysis by the Pearson chi(2) test, logistic regression model for multivariate analysis, and Kaplan-Meier method to determine survival.

RESULTS

The 5-year observed survival rate was 60.35%. The presence of histologic mandibular invasion increased the local recurrence rate. Early tumor stages (P =.02) were found to be associated with decreased local recurrence rates. Our findings indicate that tumor stage and size of mandibulectomy are more important than the type of mandibulectomy in predicting histologic bone involvement. The cases treated with a greater than 4 cm bone resection showed a lower survival rate than those treated with less than 4 cm mandibulectomy (P =.01). Patients in advanced stages (P =.006) and those with surgical margin (P =.0001) or the bone (P =.003) affected by the tumor showed a statistically significant lower survival rate. However, no statistically significant differences were found between patients treated by marginal or segmental mandibulectomy.

CONCLUSIONS

Among the prognostic factors studied, the status of the surgical resection margin, the bony involvement and the size of mandibulectomy affected the prognosis for oral carcinoma. Mandibular conservation surgery is oncologically safe for patients with squamous carcinoma in early stages. The marginal technique was not associated with worse prognosis.

Rim versus sagittal mandibulectomy for the treatment of squamous cell carcinoma: Two types of mandibular preservation

BACKGROUND

The role of conservative mandibulectomy for patients with bone invasion from squamous cell carcinoma remains poorly defined. However, marginal mandibular resection is biomechanically secure in its design while maintaining the mandibular continuity. This procedure has proven to be a successful method of treating squamous cell carcinoma with limited mandibular involvement.

PURPOSE

The purpose of this study was to analyze our results after the use of a marginal technique for the treatment of oral and oropharyngeal cancer and to compare two types of mandibular conservative procedures: rim resection versus sagittal inner mandibulectomy.

METHODS

A retrospective review of a cohort of 50 patients (global group) who underwent mandibular conservative resection for previously untreated squamous cell carcinoma was performed. Two subgroups were considered: rim group (n = 37) and sagittal group (n = 13). Clinical evaluation and preoperative radiologic studies were the means used to evaluate bony invasion and to decide on the extent of mandibulectomy. The treatment outcome after these two types of mandibular resection was calculated and compared using analysis by the Pearson chi(2) test, logistic regression model for multivariate analysis, and the Kaplan-Meier method to determine survival. RESULTS.: In the sagittal group, specimens from 2 patients (11.7%) demonstrated tumor invasion on decalcified histologic examination, whereas the rim group showed 11 cases (29.7%) with bone invasion. Local recurrence was observed in the follow-up of 10 patients. No statistical relationship was found between the presence of histologic bone invasion and the risk of local recurrence. The size of bone resection >4 cm (p =.002) and tumor invasion of surgical margins (p =.039) were found to be associated with increased local recurrence rates. In multivariate analysis, lymph node affectation significantly correlated with histologic mandibular involvement (p =.02). In the global group, the 5-year observed survival rate was 56.97%. Overall survival and rate of recurrence were comparable in both groups. In the global group, tumor infiltration beyond the surgical margin was statistically related with poor survival (p =.01).

CONCLUSIONS

Analysis of this series disclosed that marginal mandibulectomy is effective in the control of squamous cell carcinomas that are close to or involving the mandible. In carefully selected patients, sagittal bone resection seems to be as appropriate as rim resection in the local control of these tumors.

Mechanisms of cancer invasion of the mandible

There is little evidence that the tumor enters the mandible preferentially through the occlusal surface, the periodontal membrane, or named foramina. Tumor enters the mandible at the point of contact, which is often at the junction of the attached and reflected mucosa, which lies below the crest of the ridge in all but grossly resorbed mandibles. Angulation of the bone cut in rim or marginal resection of the mandible is advised. The erosive pattern of disease is associated with shallow mandibular invasion and smaller tumors in the soft tissue. This finding supports the principle of marginal resection in such cases. There is little evidence to support the principle that the tumor spreads preferentially along the inferior alveolar nerve or the bone marrow. The inclusion of the neurovascular bundle in marginal resections of the mandible is not necessary. Preoperative assessment should include plain radiography combined with a sensitive scan (bone scintigraphy, single photon emission computerized tomography, or MRI) and inspection of the bone surface after periosteal stripping at the time of the resection.