Evaluation of mandibular tumor invasion with magnetic resonance imaging

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.

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.

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.

Computed tomography in TN stage evaluation of oral cavity and oropharyngeal cancers

Oral and oropharyngeal carcinomas are characterized by a high incidence of node metastatic involvement and local extension. The study compared the TN stage of patients by clinical and computed tomography (CT) examination to postoperative histopathology. Sensitivity of CT for tumor extension was 82%, predictive value for bone involvement 67%. Clinical examination was poor in predicting the presence (54%) or absence (56%) of node involvement. Sensitivity of CT for assessment of node involvement was 80%, specificity 71%, positive predictive value 67%, and negative 83%. Node involvement was high (30%) in clinically NO necks versus only 9% for negative CT.

Evaluation of mandibular invasion by head and neck cancers using99mTc-methylene diphosphonate or99mTc-hydroxymethylene diphosphonate and201Tl chloride dual isotope single photon emission computed tomography

Whether a patient with head and neck cancer has mandibular invasion or not is important in determining the method of resection surgery. But, no modality is adequately reliable when used alone in the evaluation of mandibular invasion. Therefore, to more accurately diagnose mandibular invasion in head and neck cancer, we used a new modality, namely, 99mTc methylene diphosphonate (MDP) or 99mTc hydroxymethylene diphosphonate (HMDP) and 201Tl chloride dual isotope single photon emission computed tomography (Tc/Tl SPECT). The aim of this study is to disclose the usefulness of Tc/Tl SPECT in the assessment of mandibular invasion by head and neck cancers. 99mTc-MDP or -HMDP SPECT (Tc SPECT)s and 201Tl chloride SPECT (Tl SPECT)s were performed in 34 patients with suspected mandibular involvement of head and neck cancer. Thirty of 34 cases underwent both TcMTl SPECT and CT examination. Tc/Tl SPECT fusion images were obtained using the Automatic Registration Tool (ART, TOSHIBA, Japan) system. In the diagnosis of mandibular invasion on Tc/Tl SPECT fusion images, a problem was that the range of Tc and Tl uptake was changed by the condition of display used in the reconstruction and expression of the images. Then, prior to clinical evaluation, to reveal the most appropriate upper window level for display, a phantom study was performed. In a clinical study, the upper window level was set at 40 or 50%, which were verified to be the proper values in the preliminary study. The diagnostic accuracy obtained using Tc SPECT, TcMTl SPECT and CT was compared with the histopathological findings. Tc/Tl SPECT at 40 and 50% upper window level had higher specificity, accuracy, and positive predictive value (73.3%, 85.3%, 81.8%) than Tc SPECT alone (21.4%, 67.6%, 64.5%) and higher sensitivity and negative predictive value (94.7%, 91.7%) than CT (70.6%, 72.2%) for detecting mandibular invasion. Tc/Tl SPECT was a useful diagnostic procedure for the assessment of mandibular invasion by head and neck cancers.

Imaging in head and neck oncology

Evaluation of head and neck cancer with imaging is a topic that is far more extensive than can be covered in this article. The main reason for head and neck imaging is to evaluate the true extent of disease to best determine surgical and therapeutic options. This process includes evaluation of the size, location, and extent of tumor infiltration into surrounding vascular and visceral structures. Important anatomic variants must be pointed out so the surgeon can avoid potential intraoperative complications. These variant scan be evaluated with the appropriate multiplanar and three-dimensional images to provide as much information as possible to the surgeon preoperatively. Second, nodal staging should be assessed in an effort to increase the number of abnormal nodes detected by physical examination and, more important, to precisely define their location by a standard classification system that can be understood and consistently applied by the radiologist, surgeon, radiation oncologist, and pathologist. Although secondary to the previously described tasks, imaging frequently enables a limitation of the diagnostic and histologic possibilities based on lesion location and signal-attenuation characteristics, which may lead the clinical investigation along a different path. saving the patient unnecessary risk and shortening the time to diagnosis and ultimate treatment. This article has attempted to detail the current state of the controversy between CT, MRI, and other modalities, and has emphasized the constant evolution of this controversy because of the evolving imaging technology. Although CT and MRI are both well suited to evaluation of the deep spaces and submucosal spaces of the head and neck, each has some limitations.MRI has the advantages of higher soft tissue contrast resolution, the lack of iodine-based contrast agents, and high sensitivity for perineural and intracranial disease. The disadvantages of MRI include lower patient tolerance, contraindications in pacemakers and certain other implanted metallic devices, and artifacts related to multiple causes, not the least of which is motion. CT is fast, well tolerated, and readily available but has lower contrast resolution and requires iodinated contrast and ionizing radiation. The current authors' practice is heavily centered on CT for initial evaluation, preoperative planning, biopsy targeting, and postoperative follow-up. They reserve MRI for tumors that are suspicious for perineural,cartilaginous, or bony invasion on CT, or for tumors such as adenoid cystic carcinoma that are highly likely to spread by way of these routes. For patients who have head and neck cancer, a radiologist who is educated in the treatment options, patterns of tumor growth, and important surgical landmarks, and who has a well-established pattern of communication with the head and neck clinical services, including surgery, radiation oncology,and pathology, is key in providing accurate and useful image interpretation.

Carcinoma espinocelular de gengiva: análise das imagens de sete casos

Os autores estudaram sete casos de carcinoma de gengiva atendidos no Serviço de Cirurgia de Cabeça e Pescoço e Otorrinolaringologia e no Serviço de Diagnóstico por Imagem do Complexo Hospitalar Heliópolis, São Paulo, SP, entre 1985 e 1996. Todos os casos eram carcinomas do tipo espinocelular. Os sete pacientes eram do sexo masculino (100%), com idade variando entre 48 e 72 anos (média de 57 anos). Exame de tomografia computadorizada foi realizado em seis (85,6%) dos sete pacientes. Quatro pacientes (57,1%) eram não tratados na ocasião do exame de imagem e três pacientes (42,8%) já tinham tido algum tipo de tratamento (cirurgia ou radioterapia). Além disso, os autores analisaram o local primário e as extensões locais para a mandíbula (5/7 casos; 71,4%), para o soalho da boca (3/7 casos; 42,8%), para o soalho do seio maxilar (1/7 casos; 14,2%) e para o trígono retromolar (1/7 casos; 14,2%). Linfonodos metastáticos foram observados em cinco pacientes (71,4%). Biópsia e exame histopatológico confirmaram todos os casos. Confrontação com achados cirúrgicos foi possível em cinco casos (71,4%).

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.

Imaging the treated oral cavity and oropharynx

Cross-sectional imaging has become essential in the evaluation of the treated oral cavity and oropharynx. The purpose of this paper is to review the imaging guidelines for the evaluation of this region and to detail the typical changes encountered on imaging following surgical and radiation treatment for cancer.

[Analysis of epidermoid carcinomas using panoramic radiography and computerized tomography]

The purpose of this work was to compare radiographic findings, such as localization and extension of tumors toward the bone and soft tissues, in panoramic radiography and computed tomography (CT). Four radiologists assessed the radiographic findings of 48 patients with the histopathological diagnosis of squamous cell carcinoma in different sites of the maxillofacial region. Panoramic radiographs and computed tomographs were obtained at the University of Iowa Hospitals and Clinics, at FUNDECTO-USP and at the hospital of the University of São Paulo (USP). We observed a considerable limitation of the panoramic radiography in determining the localization and extension of tumors, since it revealed unclear delimitations. Regarding CT, better results were obtained: it was possible to observe the invasion of the tumor toward adjacent soft tissues, as well as the extension of bone destruction and the depth of the lesion, which were confirmed by surgical findings. We concluded that computed tomography demonstrated to be a sensitive radiographic technique for the detection of the involvement of bone and soft tissues, contributing for a more precise diagnosis, surgical planning and intervention. On the other hand, panoramic radiography was considered less sensitive and less efficient than CT, since it shows only unclear borders of the lesions and is not able to assess the involvement of soft tissues.

Use of intraoperative cytologic assessment of mandibular marrow scrapings to predict resection margin status in patients with squamous cell carcinoma

PURPOSE

This study assessed the feasibility of intraoperative microscopic assessment of mandibular bone resection margins in patients undergoing segmental resection of mandible for treatment of squamous cell carcinoma.

PATIENTS AND METHODS

This prospective pilot study involved 7 consecutive patients undergoing segmental resection of mandible as part of surgical treatment of oral squamous cell carcinoma. Cytologic examination of smear/touch preparations of 35 bone marrow scrapings, including simulated positive margins, was performed.

RESULTS

"Malignant" excision margins produced a high cell yield, and it was easy to assign samples to malignant or benign categories on microscopic examination. All the simulated positive margins were easily identified. No false positive results were found.

CONCLUSION

Cytologic examination of bone excision margin scrapings is a rapid, inexpensive, and accurate technique. This study confirms its feasibility and accuracy in cases of mandibular resection for squamous cell carcinoma.

CT detection of mandibular invasion by squamous cell carcinoma of the oral cavity

OBJECTIVE

The purpose of this study was to determine the diagnostic accuracy of CT in detecting mandibular invasion by squamous cell carcinoma of the oral cavity.

MATERIALS AND METHODS

Forty-nine patients who had squamous cell carcinoma of the oral cavity that was clinically fixed to the mandible were treated with mandibulectomy. All patients underwent contrast-enhanced CT (contiguous 3-mm-thick sections) through the primary site before surgery. All studies were reconstructed with bone algorithm. These studies were retrospectively reviewed by a neuroradiologist for evidence of mandibular invasion. The imaging results were compared with the histologic findings in all cases.

RESULTS

CT correctly revealed 25 of 26 cases with mandibular invasion. CT correctly excluded mandibular invasion in 20 of 23 cases without invasion. The diagnostic accuracy of CT for detecting mandibular invasion was as follows: sensitivity, 96%; specificity, 87%; positive predictive value, 89%; and negative predictive value, 95%.

CONCLUSION

Thin-section (3-mm) CT reconstructed with bone algorithm is an accurate technique to detect mandibular involvement by squamous cell carcinoma of the oral cavity.

Technetium 99m single positron emission computed tomography scanning for assessing mandible invasion in oral cavity cancer

OBJECTIVES

To study the accuracy of single positron emission computed tomography (SPECT) scanning and compare its results to clinical examination, Panorex, and computed tomography (CT) scanning with respect to determining mandibular invasion by oral cavity and oropharyngeal cancer, and to define the role of SPECT scanning in the preoperative assessment of oromandibular cancer.

STUDY DESIGN

Prospective study of 38 patients who underwent technetium 99m SPECT scanning as part of their preoperative clinical assessment for cancer at risk of invading the mandible. All patients underwent partial or segmental mandibulectomy as part of their surgical management.

METHODS

A data protocol was used to tabulate patient demographics, tumor characteristics and results of preoperative tests as patients were enrolled into the study. Following surgical treatment, these data were correlated with histopathological findings. Detailed analysis was performed to assess the tabulated data.

RESULTS

The SPECT scanning demonstrated an 87% overall accuracy in predicting bone invasion compared with 71% for clinical examination, CT scanning, and Panorex x-rays. The SPECT scanning was significantly more sensitive (95%) than either CT scans (55%) or Panorex x-rays (50%). Notably SPECT scanning demonstrated a considerable improvement in specificity (72%) compared with conventional radionuclide scanning. Although not as specific as CT scanning or plain films, SPECT scanning was significantly more effective in ruling out disease than was clinical examination.

CONCLUSIONS

Preoperative SPECT scanning used in combination with clinical examination, CT scanning, and Panorex x-rays to assess patients at risk for mandible involvement by oral cavity cancer can improve the accuracy of predicting bone invasion and help in appropriate treatment planning so as to safely reduce the proportion of disease-free jaws resected.

Outcome of squamous cell carcinoma of the gingiva: a follow-up study of 83 cases

BACKGROUND

Squamous cell carcinomas of the gingiva are relatively rare tumours. Standard treatment is based on surgery and radiotherapy. The extent of bone involvement affects mandibulectary indications.

PURPOSE

A retrospective review of squamous cell carcinomas of the gingiva was performed to evaluate the incidence of mandibular or maxillary bone involvement. Indications for marginal and segmental bone resections are specified.

MATERIAL

From 1985 to 1996, 83 patients with squamous cell carcinoma of the gingiva were treated at the Department of Surgery (Institut Bergonié, Bordeaux, France) and at the Department of Maxillofacial and Plastic Surgery (Centre Hospitalier Universitaire, Bordeaux, France). Forty-three underwent surgery plus postoperative radiotherapy. Twenty-two had flap reconstructions. Clinical evaluation and panorex roentgenography were the means used to evaluate bony invasion and to decide on the extent of bone resection.

METHODS

A retrospective review of 83 consecutive patients was performed. This series is unusual in its homogeneity: surgery was performed by only two individuals and the radiotherapy was the responsibility of just two physicians. Outcome was calculated using the Kaplan-Meier method.

RESULTS

Primary local control was achieved in 72 patients (87%). Overall survival and rate of recurrence were comparable to those of other squamous cell carcinomas of the oral cavity and oropharynx.

CONCLUSION

Surgical resection continues to be the mainstay of treatment and this study tends to confirm the validity of modified neck dissection and marginal bone resection in suitably selected patients.

Mandibular invasion in carcinoma of the lower alveolus

PURPOSE

Efforts to conserve the mandible in resection for oral cancer tend to bring the resection margin progressively closer to the tumor front. This study of the manner of mandibular invasion by carcinoma of the lower alveolus provides added information regarding the behavior of the cancer within the bone.

MATERIALS AND METHODS

Twenty-four resected specimens of squamous carcinoma of the lower alveolus were studied with x-rays and step-serial whole-organ histological sections.

RESULTS

In 19 of the 21 specimens showing bone invasion, the spread was in the form of a broad front. Insinuation of tumor beyond the tumor front was extensive in 9 of 13 tumors showing deep mandibular invasion. Horizontal subcortical spread took place in 5 of 18 specimens for a distance of up to 1 cm. Perineural spread along the inferior alveolar nerve was found in 4 of 13 specimens in which the tumor extended to the canal; tumor spread along the canal, without neural involvement, was never seen. Preoperative orthopantomogram correctly estimated the extent of mandibular invasion in 16 of 24 patients.

CONCLUSIONS

The tumor front of mandibular invasion by carcinoma of the lower alveolus is usually broad. In the absence of deep invasion, which is defined by invasion reaching the alveolar canal, there is little or no insinuation of cancer cells beyond the tumor front, and no spread along the alveolar canal. Marginal mandibulectomy can be applied more widely, taking a margin of 1 cm in all directions.

Autoradiographic evaluation of 99mTc-methylene diphosphonate accumulation in oral cancer invading the mandible

PURPOSE

Skeletal scintigraphy, a sensitive diagnostic tool used to detect changes in bone, is helpful for evaluating bone invasion by oral cancer. However, the exact sites of accumulation of 99mTc-phosphate compounds in the mandible have not yet been fully elucidated. The aim of this study was to determine the localization of 99mTc-methylene diphosphonate (MDP) in the areas of mandible that have been invaded by cancer.

PATIENTS AND METHODS

Seven patients with oral cancer (lower gingiva, 4; tongue, 2; floor of the mouth, 1) who underwent surgical treatment with mandibular bone resection were included in the study. Autoradiography and contact macroradiography were used for evaluation of 99mTc-MDP accumulation.

RESULTS

Radioactivity reflecting accumulation of 99mTc-MDP was documented encircling the portion of the mandible with cancerous invasion, suggesting that 99mTc-MDP accumulated in immature bone. High uptake also was found in the periosteal reactive bone around the cortical bone.

CONCLUSIONS

The amount of increased 99mTc-MDP circumscribing carcinoma invasion varies among cases. Additionally, uptake may not correspond directly with the amount of the carcinoma invasion; that seen in periosteal bone could be attributed mistakenly to bone invasion in planar scintigraphy.

Update on intraoperative analysis of mandibular margins

PURPOSE

Assessing the adequacy of the surgical resection during composite resection of carcinoma is limited by the ability to evaluate the bone margins. The standard pathologic evaluation of bone is by decalcification.

PATIENTS AND METHODS

A method of analysis was devised based on histologically proven methods of cortical invasion and subsequent spread. Frozen-section analysis of cancellous bone was investigated as a rapid method of evaluating adequacy of the mandibular resection. This report is an update of previously published results and includes an increase in the sample size as well as the analysis of additional pathology. Subjects consisted of 66 patients undergoing full thickness mandibular resection with 30 cases of histologically proven mandibular invasion qualifying for evaluation. Results on frozen section were then compared to the permanent section analysis on the cancellous bone and to the decalcified specimen.

RESULTS

Complete correlation was found between frozen and permanent section results. Frozen section analysis was able to correctly predict adequacy of resection in 60 of 61 margins.

CONCLUSION

Based on these results, the oncologic surgeon can evaluate bone margins at the time of the resection and adjust the amount of excision required to eradicate the disease.

DentaCT for evaluating mandibular and maxillary invasion in cancer of the oral cavity

We used a retrospective analysis of charts, imaging studies, and histologic findings when available in 17 patients with cancer of the oral cavity to define the value of DentaCT or multiplanar reformation software in assessing bony involvement by malignant tumors of the oral cavity. From two academic tertiary-referral medical centers, the 17 patients had a mean age of 63 years and suspected maxillary (2) or mandibular (15) invasion. All patients had conventional computed tomography scanning and multiplanar reformation scans with several additional imaging studies obtained. Two patients demonstrated no bony involvement by imaging and histologic studies. Twelve of the remaining 15 patients had surgically documented bony involvement also correctly detected by DentaCT. DentaCT was found to be a valuable tool in defining extent of bony invasion by tumor. Although not compared to other imaging modalities, our experience supports the use of DentaCT where available for this purpose.

Mandibular invasion by squamous cell carcinoma: a computed tomographic and histological study

Our knowledge of the entry and spread of oral cell carcinoma (SCC) into the mandible is increasing, making an impact on surgical planning. Fourteen resection specimens of mandibular bone and adjacent SCC were radiographically (CT) and histologically investigated. In six cases there was no involvement of mandibular bone; a continuous periosteal layer separated the tumour from bone. The remaining eight specimens showed bony involvement with good correlation between corresponding CT and histological slices in the five edentate cases. The site of entry of the tumour into the bone was usually through the alveolar crest with additional spread through the lingual cortex in tumours that lay lingual to the mandible. Although limited, our data shows that the main site of entry of SCC is through the alveolar crest. It also highlights the usefulness of CT in the identification of bone involvement in edentate cases. This information may assist in the planning of operations to preserve as much bone as is consistent with complete excision of the tumour.

Bone scintigraphy in detection of bone invasion by oral carcinoma

Detecting osseous involvement is clinically important in the management of oral carcinoma. Thirty-one patients with osseous involvement due to oral carcinoma who underwent panoramic radiography and bone scintigraphy were evaluated retrospectively. Bone scintigraphy confirmed osseous involvement in all 31 (100%) of these patients. In 27 (87%) of 31 patients with osseous involvement, both the panoramic radiogram and bone scintigram were positive. In the remaining four patients (13%), bone scintigram was positive for mandibular or maxillary invasion, while panoramic radiogram was negative. There were no instances of an abnormal radiogram with a normal bone scintigram. These findings strongly suggest that bone scintigraphy is more sensitive than panoramic radiography in detecting osseous involvement of the mandible and maxilla due to oral carcinoma. Furthermore, bone scintigraphy was a critical pre-surgical in determining the extent of the osseous involvement.

Rapid analysis of mandibular margins

Evaluating surgical margins during composite resection of carcinoma is limited by analysis of the bone margins. The standard pathologic evaluation of bone is by decalcification. A method of analysis was devised based on histologically proven methods of cortical invasion and subsequent spread. Frozen section analysis (FSA) of the cancellous bone was investigated as a rapid method of evaluating adequacy of the mandibular resection. Subjects consisted of 29 patients undergoing full-thickness mandibular resection, with 16 cases of histologically proven mandibular invasion qualifying for evaluation. Results of FSA were then compared to the permanent section analysis of the cancellous bone and to the decalcified specimen. Complete correlation was found between frozen and permanent section results. Frozen section analysis was able to correctly predict adequacy of resection in 32 (97%) of 33 margins.

Magnetic resonance imaging: practical theory and clinical relevance

Magnetic resonance imaging can be a valuable diagnostic tool. Some fundamental concepts behind MRI are discussed, using clinical cases to illustrate the potential of this imaging system.

Predictors of carcinomatous invasion of the mandible

The preoperative assessment of mandibular invasion by oral or oropharyngeal squamous cell carcinoma poses a challenge for the head and neck surgeon. A study of 64 composite resection patients was performed to determine which variables in the patient's history, physical exam, and diagnostic workup had a predictive association with carcinomatous mandibular invasion. Four postoperative variables were included in this analysis. Thirty-nine percent of the mandibular specimens demonstrated cancerous involvement. A multivariate recursive partitioning statistical analysis was performed to create a decision tree. Branching was based on the two statistically predictive variables: computed tomographic (CT) scan results and primary tumor location. The guide provides improved predictive accuracy with a 100% negative predictive value (NPV) and a 46% positive predictive value (PPV). This decision guide should help the surgeon provide accurate patient counseling, anticipate reconstructive needs, and maximize surgical oncologic effectiveness.

DentaScan imaging of the mandible and maxilla

DentaScan is a unique new computer software program which provides computed tomographic (CT) imaging of the mandible and maxilla in three planes of reference: axial, panoramic, and oblique sagittal (or cross-sectional). The clarity and identical scale between the various views permits uniformity of measurements and cross-referencing of anatomic structures through all three planes. Unlike previous imaging techniques, the oblique sagittal view permits the evaluation of distinct buccal and lingual cortical bone margins, as well as clear visualization of internal structures, such as the incisive and inferior alveolar canals. Several case reports are presented to demonstrate the clinical usefulness of DentaScan.

Major surgery of oral and oropharyngeal carcinoma

Thirty-two composite resections were carried out in the Department of Otolaryngology at Groote Schuur Hospital for oral and oro-pharyngeal squamous carcinoma over the 10-year period, 1977-1986. Three patients were lost to review but all others were followed up to death or to five years. Twenty-seven patients underwent surgery as their primary procedure and five for recurrence after primary radiotherapy. The overall survival was 16 patients at three years and eight at five years. Only one of the five patients who underwent salvage surgery after failed radiotherapy was alive at five years and all five experienced serious postoperative complications. All those surviving over five years had had either N0 or N1 disease at the time of presentation for surgery.