Journal of Indian Academy of Oral Medicine and Radiology

: 2021  |  Volume : 33  |  Issue : 2  |  Page : 157--162

Association of pattern of mandibular invasion in MDCT with recurrence in oral cancers

Vishal Thakker, Manali Arora, Nisarg Thakkar 
 Department of Radio-Diagnosis, Pramukhswami Medical College, Karamsad, Gujarat, India

Correspondence Address:
Dr. Manali Arora
H.NO 1546, Sector 15, Sonipat, Haryana - 131001


Background: Mandibular invasion has been a long-debated criterion for predicting prognosis in oral cancers. Though the American Joint Committee on Cancer (AJCC) marks cortical erosion in oral lesions as T4 disease, it is often challenged that mere superficial bony erosion should not be used to demark T4 disease. Aim: This study aimed to evaluate the association of pattern of mandibular erosion in preoperative Multi-Detector CT (MDCT) of oral cancers with the presence of recurrent loco-regional malignant disease. Materials and Methods: A retrospective study was done in the Department of Radio-Diagnosis of a tertiary center in Western India. MDCT Neck findings in 56 consecutive postoperative patients clinically suspected for recurrent oral carcinoma over a period of 1 year were assessed. Preoperative MDCT of all patients was evaluated for presence and pattern of mandibular involvement by primary malignancy. These patterns were compared with the presence of recurrent disease in the postoperative scan. Association between two findings was tested by Fisher's exact test. Results: Forty-eight patients showed features of recurrent malignancy on MDCT confirmed by biopsy; of which 10 patients had shown no bony invasion in the preoperative scan, 14 had shown cortical erosion and 24 showed medullary invasion. P value for association of recurrence and bony invasion pattern was found to be 0.6705 (insignificant) for cortical erosive lesions and 0.0469 (significant) for medullary infiltrative lesions. Conclusion: Only medullary infiltrative lesions of the mandible have a statistically significant association with recurrent disease and may be used as a prognostic factor. Cortical erosions are statistically insignificant in predicting recurrence similar to no bone invasions.

How to cite this article:
Thakker V, Arora M, Thakkar N. Association of pattern of mandibular invasion in MDCT with recurrence in oral cancers.J Indian Acad Oral Med Radiol 2021;33:157-162

How to cite this URL:
Thakker V, Arora M, Thakkar N. Association of pattern of mandibular invasion in MDCT with recurrence in oral cancers. J Indian Acad Oral Med Radiol [serial online] 2021 [cited 2022 Oct 3 ];33:157-162
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With continued exposure to the major causative factor of Tobacco, postoperative recurrence in Oral Cancer is a dreaded clinical scenario with increased morbidity and mortality. Underlying bone invasion is an important tendency of oral cancers, especially in edentulous mandible, open tooth sockets form a path for tumor cells to invade the bone. The American Joint Committee on Cancer (AJCC) demarks mandibular invasion as T4 disease; however, the significance of pattern of invasion remains a debatable issue. In multiple studies, attempts have been made to identify prognostic factors of recurrence in oral cancers such as lesion size, histological differentiation, nodal staging, adjacent soft tissue involvement are known factors affecting prognosis. Mandibular invasion and its types as an independent prognostic indicator is still an issue of debate with multiple conflicting studies. Most of these are pathological studies that analyze the postoperative surgical samples.[1],[2],[3]

In the present study, we aim to analyze the association of patterns of mandibular invasion on MDCT with postoperative loco-regional recurrence of Oral Cancer, thereby aiming to determine the role of imaging in depicting the prognosis in oral cancer.

 Materials and Methods

After due clearance from the institutional ethical committee for analysis of hospital-based data via letter no IEC/HMPCMCE/2018/Ex. 28, a retrospective analytical study was done by reviewing the MDCT neck findings of postoperative patients who had undergone surgery for oral carcinoma; coming to our department for a period of 1 year. “All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.”

The study aimed to evaluate the association of pattern of mandibular invasion in preoperative MDCT necks in patients of pathologically proven oral cancers with the presence of recurrent malignant disease in postoperative MDCT.

Inclusion criteria

All patients who underwent MDCT neck at our department after surgical treatment for Oral carcinoma.All such patients whose preoperative imaging was available for comparison with the postoperative scans.

Exclusion criteria

All patients whose previous imaging/surgical details were not available for comparison.

Design of study

Clinical notes with details of oral examination and surgical details were retrieved from the hospital database. The data of all patients who had undergone a contrast-enhanced CT scan of the neck on a 128 Slice Optima CT 660 (Wipro GE Healthcare Pvt. Ltd.), after a surgical resection of oral carcinoma was included in the study. The prerequisites before a CT scan included a normal renal function test (Serum creatinine and creatinine clearance), and a written informed consent from the patient, for an intravenous contrast study. Non-contrast and contrast-enhanced 5 mm thick contiguous helical MDCT sections of neck were performed from the base of skull to thoracic inlet before and after giving intravenous administration of 100 ml non-ionic iodinated contrast medium. Few 5 mm coronal and sagittal reconstructions were done through the region of interest. The three-dimensional reconstructed and multiplanar reformatted images were obtained. Reconstruction parameters included slice thickness of 3 mm and reconstruction increment of 3 mm. Both source and reconstructed images of MDCT neck were analyzed in both postoperative and preoperative scans.

A single radiologist, with 5 years of experience in head and neck imaging, blinded to the preoperative imaging findings, retrospectively analyzed the MDCT data of the patients included in the study and thereafter compared them with the available preoperative MDCT findings and surgical notes from the hospital database.

The mandibular invasion pattern in preoperative scans was demarcated in three categories: No Invasion, Cortical Erosion, Medullary Infiltration.

Statistical analysis of association of recurrent disease with each pattern of bone invasion was done by Fisher Exact Test. P value thus obtained was used to demark the said pattern of bone invasion as significant or non-significant in predicting recurrent disease.

Since the study was a retrospective data analysis, where patients had already undergone the said examination, a consent waiver was obtained from the Ethical Committee.


Our study group comprised 56 patients with males comprising more than 90% of the study group. The most common decade of presentation was the sixth decade with the mean age of presentation being 53.2 years. Tobacco intake is a common social habit in the given study area, which is reprised in the study group with more than 2/3rd of the subjects giving a history of tobacco use. The demographic profile of the study group is presented in [Table 1].{Table 1}

Of the 56 patients presenting for CT imaging with clinical suspicion of recurrence, CT detected suspicious lesions in 50 patients. Of this a pathological recurrence was proven in 48 patients with two false positives in imaging, one of which was mandibular osteonecrosis and the other inflammatory soft tissue on pathology. Six patients had no discernible imaging signs of recurrent disease. MDCT thus had a PPV of 96% in detecting postoperative recurrence. It was observed that of the eight patients that did not show any pathological recurrence, four had no bone erosion in the preoperative scans, three had cortical erosions while only one case had medullary infiltration in the preoperative scans.

The preoperative imaging of the 48 pathologically proven patients of recurrent loco-regional malignant disease was thereby assessed. While more than one site of involvement was a common occurrence in the study group, the most common site of primary disease was buccal mucosa (n = 41, 85.41%) followed by Gingivo buccal sulcus (n = 33, 68.76%). The most common pattern of mandibular involvement was medullary involvement or gross destruction of the mandible in half of the study group (n = 24, 50%), while cortical erosion only was found in 14 cases. Accordingly, while assessing the surgical details, it was observed that segmental mandibulectomy was performed in all cases of medullary involvement (n = 24, 50%) while marginal mandibulectomy was performed in 16 cases based on clinico-radiological observations. The most common site of recurrence was the surgical flap (n = 21, 43.75%). Recurrence at a new site within the oral cavity was an uncommon occurrence within the study group (n = 4, 8.33%). Clinical and surgical details are represented in [Table 2] and [Figure 1].{Table 2}{Figure 1}

On analysis of association of pattern of individual mandibular involvement with recurrent disease, it was observed that 17 patients had cortical erosions in preoperative scans, of which 14 had postoperative recurrence while three patients did not. In preoperative scans, 25 patients showed mandibular medullary involvement or gross tabular destruction of which 98% patients (n = 24) showed postoperative recurrence. This was found to be statistically significant when compared with recurrence in patients with no preoperative mandibular involvement. However, there was no statistically significant association between cortical erosion and recurrent disease in our study. The statistical analysis of the study is represented in [Figure 2] and [Figure 3]. Few representational cases are shown in [Figure 4] and [Figure 5].{Figure 2}{Figure 3}{Figure 4}{Figure 5}


Oral carcinoma is one of the most common cancer in India with 30% of all types of cancer.[4] It is the second most common cancers in the Indian men, second only to lung carcinoma with the highest age-specific incidence rate of 58.4 in the high tobacco consumption west zone.[5],[6] Despite advances in diagnosis and therapeutic measures, the menace of recurrence is very high in oral cancers, with various studies in literature reporting approximately 35% recurrent cases in different geographical zones and overall survival rate of around 50%.[7],[8],[9] This makes analysis of prognostic factors essential in order to predict recurrence and provide adjuvant therapies accordingly.[9]

Our study group comprised male-dominant population (91%) with maximum prevalence in the sixth decade. A history of high tobacco consumption (69%) was found in the study group as is seen in other studies also.[7],[10]

Mandibular invasion has been a much-discussed criterion as a prognostic marker for oral cancers. The AJCC 8th edition has described bony cortical as well as medullary involvement as T4 disease, except for superficial involvement of the tooth sockets where cortex is not involved. On univariate analysis, our observations suggested that mere cortical erosion had no significant association with recurrent disease. However, medullary invasion including both medullary canal involvement and tabular destruction of bone had statistically significant association with recurrent disease even after segmental mandibulectomy was performed. Thus, on a preoperative scan, only medullary invasion of the mandible merited to be designated as an independent prognostic factor and should be used to upstage T staging to Stage 4.

There are multiple conflicting studies in literature, with both similar and discrepant results. A recent study by Lee et al.[10] which analyzed both imaging and histological factors, also found that Mandibular canal involvement and complete bony destruction were independent prognostic factors for oral carcinoma. Shaw et al.,[11] also emphasize that the pattern of bony infiltration is crucial and upstaging of disease on the basis of bony invasion is necessary. However, various other studies made specific observations on the basis of size and other confounding factors such as T staging, including the study of Fried et al.,[12] who found worse outcomes in patients with medullary invasion. In contrast to this, Fives et al.[13] observed that medullary invasion was associated with poor prognosis irrespective of lesion size. Wong et al.[14] found a high recurrence rate in their study group in patients with medullary involvement (53%) in comparison to that of cortical erosion only (17%). Ebrahimi et al.[1] while analyzing mandibular invasion as an independent prognostic factor in a multivariate analysis done on 498 patients concluded that medullary and not cortical invasion is an independent prognostic factor for overall survival in oral cancers with a P value of 0.037, more so in determining distant metastases rather than locoregional disease. Du et al.[15] observed that bone invasion irrespective of type significantly reduced loco-regional disease control. A meta-analysis of 18 studies performed by Li et al.[16] observed that mandibular erosion in general cannot be a reliable prognostic marker while medullary invasion is an independent prognostic marker for oral carcinoma. [Table 3] depicts a comparative analysis of our study with the study of Shaw et al.[11]{Table 3}

On the other hand, multiple researchers could not establish a significant association between bone invasion and disease prognosis. Ash et al.[17] observed that pattern of bony involvement was a significant risk factor for recurrence. Patel et al.[18] observed that there was no prognostic impact of extent of mandibular invasion in patients of oral cancer undergoing mandibulectomy. Similarly, Muñoz Guerra et al.[19] and Tankéré et al.[20] also could not establish an association between bony invasion and disease prognosis.

Limitations and future prospects

In such a conflicting issue, our study had multiple limitations, first being a retrospective analysis where surgical specimens and pathological details were available in limited capacity. Details of adjuvant treatments taken by patients were also limited. We could not determine the exact time of disease-free period as recurrent patients presented after various periods of disease onset. Despite this, the authors felt it was essential to project the radiologist's perspective and potential role in depicting and deciphering the role of such an important clinico-radiological finding of bone invasion in oral cancer.


Bone invasion should be depicted as an independent prognostic factor for oral carcinoma with only medullary invasion of the mandible on MDCT showing strong association with postoperative locoregional recurrence. Superficial cortical erosion of the mandible does not show statistically significant association with recurrence and hence cannot be used as an independent prognostic indicator.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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