Reaction of alveolar bone to invasion of oral carcinoma

Patterns of invasion and routes of tumor entry into the mandible by oral squamous cell carcinoma

BACKGROUND

An understanding of the patterns, spread, and routes of tumor invasion of the mandible is essential in deciding the appropriate level and extent of mandibular resection in oral squamous cell carcinoma.

METHODS

A prospective study of histologic patterns of tumor invasion and routes of tumor entry into the mandible was performed in a consecutive series of 100 previously untreated patients.

RESULTS

The pattern of tumor invasion of the mandible depended on the depth of invasion both in the hard (p =.001) and soft tissues (p =.001). There was evidence that the pattern of invasion was related to histologic prognostic indicators of the disease, such as extracapsular spread from invaded lymph nodes (p =.03). The route of tumor entry was at the point of abutment to the mandible (direct) in all 13 cases, invading the dentate part of the mandible. Fifty-five percent (23 of 42) of tumors invading the edentulous ridge entered through the occlusal (superior) surface. Direct entry to the mandible in the edentulous ridge was more likely for tumors arising in the tongue, floor of the mouth and the buccal mucosa compared with alveolar or retromolar sites (p =.003)

CONCLUSIONS

Larger or more deeply invading tumors in the soft tissue are more likely to invade the mandible and show the more aggressive (invasive) form of tumor spread, reducing the options of a more conservative (rim) resection. Tumors tend to enter the mandible at the point of abutment, which in both the dentate and edentulous jaw is often at the junction of the reflected and attached mucosa. A point of tumor entry below the occlusal ridge or gingival crest should be assumed when planning rim or marginal resections of the mandible.

Factors influencing the patterns of invasion of the mandible by oral squamous cell carcinoma

The pattern of tumour invasion of the mandible depends on the extent of invasion. Both the width (P = 0.02) and depth (P = 0.01) in patients with an invasive or infiltrative pattern of disease were greater than in tumours showing the less aggressive erosive pattern in which the tumour mass is separated from the resorbing bone by a connective-tissue layer. Evidence in this study suggests that the erosive pattern develops through a mixed pattern to the invasive pattern of disease as the tumour progresses through the bone. The invasive pattern of disease was evident at a much shallower depth in the molar region of the mandible (mean 9 mm), with a decreased ratio of alveolar to basal bone, than in the premolar and parasymphyseal region (mean 25 mm) (P = 0.02). The hypothesis to explain this phenomenon is that the more superficial alveolar bone responds by resorbing in advance of the tumour, but the basal bone is unable to respond in the same way and becomes widely infiltrated. The attached mucosa with its firm collagen attachment to bone is proposed as the main route of tumour entry into the mandible in both dentate and edentulous mandibles.

Parathyroid hormone related protein in oral squamous cell carcinomas invading the mandible

AIM

To assess parathyroid hormone related protein (PTHrP) as a candidate biochemical marker of invasion of the mandible by oral squamous cell carcinoma.

METHODS

Tumour PTHrP concentrations were quantitated by immunoassay, and PTHrP was detected by immunohistochemistry, in a cohort of 24 primary squamous cell carcinomas of the mandible.

RESULTS

PTHrP was identified in all tumours examined, but no correlation was found between scores of the intensity and/or consistency of staining or tumour PTHrP concentrations and the histological classification of tumour invasion.

CONCLUSION

Although PTHrP was present in all squamous tumours studied, there was no correlation between PTHrP expression and pattern of tumour invasion. However, tumour derived PTHrP may act locally to influence tumour growth and differentiation and resorption of bone.

Results of surgical treatment for squamous carcinoma of the lower alveolus: segmental vs. marginal resection

The records of 53 patients treated surgically for squamous cell carcinoma of the lower alveolar ridge were reviewed and the results of segmental and marginal resections of the mandible were compared. Analysis of these 2 treatment modalities disclosed that marginal resection was effective in controlling lower gingival cancers, with and without apparent bone involvement, if erosive bone defects that did not extend beyond the inferior alveolar canal, or invasive bone defects confined to a superficial area of the alveolar bone, were detected radiologically.

Mandibular involvement by squamous cell carcinoma of the lower alveolus: analysis and comparative study of histologic and radiologic features

Histologic analysis of squamous cell carcinoma of the lower alveolus shows 2 basic patterns of tumor spread in relation to the mandible: an infiltrative one and an expansive one. While the tumor invades the mandible by destroying the bone or through cortical defects of some spaces in the infiltrative form, the tumor does this only by eroding the bone in the expansive form, in which the degree of bone resorption seems to be proportional to tumor advancement. A comparison between radiologic and histologic features discloses that the radiologically detected bone defects are not necessarily correlated with the patterns of bone involvement. However, most lesions with erosive bone defects show the expansive pattern histologically, and the extent of the radiologically detected bone defect is roughly in accordance with the histologic extent of bone involvement. These results lead us to believe that some squamous carcinoma of the lower alveolus could be treated successfully without sacrificing the continuity of the mandible.

Histopathologic study of bone invasion by DMBA-induced carcinoma of the mouth in the hamster

Carcinoma was induced in the floor of the mouth in the hamster, and the mechanism of bone invasion was studied microscopically. Conclusions are as follows: The periosteum is destroyed and, in general, the external surface of the cortical bone is resorbed through osteoclastic action. However, the periosteum at times resists the invasion of tumors. As the cortical bone is resorbed to some extent and tumor replaces the resorbed area, Volkmann and haversian canals begin to enlarge. Following enlargement of the canals, tumor invasion results in enlargement of the canals of the cortical bone far from the invaded area. In addition, tumors invade the periodontal space and resorb the inner surface of the alveolar bone. Tumors invade the bone marrow through the enlarged haversian canals or the periodontal space or by direct resorption of cortical bone, thus replacing the marrow spaces.

Facial bone scintigraphy. VIII. Diagnosis of malignant lesions in the maxillary, ethomoidal and palatal bones

The results from radiographic and scintigraphic examination of 28 patients with malignant tumors of the nasal, paranasal and palate regions, 23 patients with purulent maxillary sinuitis, and 15 control cases were compared. A combination of radiography and scintigraphy yielded the best information on the differentiation between an inflammatory condition and malignant tumor and the extent of malignant growth in adjacent bone.

Facial bone scintigraphy. VII. Diagnosis of malignant lesions in the mandible

Fifty-four patients were examined clinically, radiographically and scintigraphically with respect to mandible bone involvement by oral carcinoma. Sixteen resected mandibular specimens were available for microscopic examination and the results were correlated to the clinical, scintigraphic and radiographic results. Clinical assessment overestimated and radiography underestimated oral carcinoma involvement of the mandible; scintigraphy was more accurate than was clinical assessment or radiography. Combination of clinical examination with both conventional radiography and bone scintigraphy is recommended for optimum diagnosis of mandible bone involvement by oral carcinoma.

Squamous-cell carcinoma of the floor of the mouth with extensive mandibular involvement

The case of a patient with an extensive squamous-cell carcinoma of the floor of the mouth with erosion of the mandibular bone is presented. The history and initial clinical picture were consistent with either carcinoma with superimposed infection or chronic osteomyelitis with an acute exacerbation. A discussion of diagnosis and treatment of carcinoma of the floor of the mouth follows this case report.