- Email: [email protected]
The marginal mandibulectomy for the treatment of mandibular tumours
British Journal of Oral and Maxillofacial Surgery (1989) 27, 132-138 @ 1989 The British Association of Oral and Maxillofacial Surgeons
0266 4356Xl89/0027-0132/$10.00
THE MARGINAL MANDIBULECTOMY FOR THE TREATMENT OF MANDIBULAR TUMOURS M. A. POGREL, M.B., ch.B.,B.D.s.,F.D.s.R.c.s., F.R.C.S. The Division of Oral and Maxillofacial Surgery, San Francisco
The University of California,
Summary. With the knowledge and techniques gained from orthognathic surgery and more precise imaging techniques, it has become more practical to carry out rim or marginal resections for some malignant tumours of the alveolus to preserve mandibular continuity and yet have adequate tumour margins. This is of great functional and cosmetic importance to the patient. A study of 11 patients is presented to analyse criteria for carrying out this procedure.
Introduction Since the 1940’s, malignant disease of the mandible, mandibular alveolar mucosa and related lingual and buccal mucosa, primarily has been managed surgically, since radiation in close proximity to the mandible runs a significant risk of precipitating osteoradionecrosis (Morrish et al., 1981). Furthermore, radiotherapy as primary treatment is often ineffective in controlling lesions involving the mandible (Quick, 1926; Mattick & Meehan, 1951; Lampe, 1955). Radiation is, however, often given as a combined therapy with surgery. The traditional surgical approach to these lesions involves a composite resection of the mandible and associated soft tissues. This is frequently carried out in continuity with a radical neck dissection or modified neck dissection if there are clinically involved nodes or if the incidence of occult nodes is felt to justify this treatment (Slaughter et al., 1949). Nahum et al. (1976) present an excellent review of the case for and against elective neck dissection and conclude that there is no factual basis for the procedure. Elective irradiation of the neck (Fletcher, 1982) is a preferable modality if required, in most instances. Segmental resection of the mandible allows easy access to the tumour bed and can facilitate primary soft tissue closure. Yet, the problems of reconstruction and rehabilitation following this form of surgery are considerable. Though some people appear to be able to function fairly well without a portion of mandible and others can tolerate the cosmetic deformity, in many cases reconstruction is necessary. To date, a purely prosthetic approach utilising meta!lic or other implants has not met with long term success. To achieve successful reconstruction, both bone and soft tissue must be used, and though free bone grafts and soft tissue flaps can be used, many surgical techniques now utilise myocutaneous and osteomyocutaneous flaps. There are a wide variety of such pedicled or free flaps which have been utilised for mandibular reconstruction, but they all have associated problems (McGregor & McGregor, 1986). In recent years a small number of studies have examined the feasibility of carrying out a marginal resection of the mandible for alveolar carcinoma, preserving a rim of the inferior or lateral border of the mandible, with obvious functional and cosmetic advantages (Converse, 1977; Beecroft et al., 1982; Wald & Caliaterra, 1983; Gilbert et al., 1986; McGregor & McGregor, 1986). These studies (Received
7 January
1988; accepted 30 April 1988)
132
TREATMENT
OF MANDIBULAR
TUMOURS
133
vary considerably in terms of patient selection and treatment modalities, since there are a variety of combinations of local resection plus or minus associated radical neck dissection and possibly combined with radiotherapy. However, they do appear to show that in selected cases similar success rates can be obtained with a marginal resection of the mandible preserving the lower border as opposed to a more conventional segmental resection removing the whole thickness of the mandible. One argument which has been given against marginal resection of the mandible is that the lymphatic drainage from the alveolus and the floor of the mouth passes on the lingual periosteum and that if this is not fully resected in continuity with the tumour, recurrence is likely (Ward & Robben, 1951). It has been shown, however, that these lymphatics do not lie on the lingual periosteum and that this periosteum can often be spared (Marchetta et al., 1971). Even when the periosteum must be resected, the specimen is removed in continuity with the lingual plate and the remaining mandible left in situ. Criteria have been formulated to define those tumours which may be suitable for marginal resection of the mandible. It appears that T-l and T-2 tumors may be suitable, with similar cure rates for marginal or segmental resection in both Stage I and Stage II disease (Byers et al., 1981). To be suitable for marginal resection, it has also been suggested that there should be no preoperative evidence of bone involvement and no perineural involvement as determined by plain radiographs and clinical examination. The tumour may extend through to periosteum but
Fig. I Figure l-Area
of increased uptake on TcW polyphosphate bone scan in left anterior mandible (arrowed). Specimen confirmed tumour invasion in same area.
134
BRITISH
JOURNAL
OF
ORAL
&
MAXILLOFACIAL
SURGERY
should not involve bone (Wald & Caliaterra, 1983). Studies on marginal resection of the mandible have generally described this as being performed from an extraoral approach which often includes a lip-splitting technique. Because earlier criteria for marginal resection were based on clinical examination and plain radiographs, it was felt that modem imaging techniques such as radioisotope imaging, CT scanning and magnetic resonance imaging (MRI) studies may help to delineate more accurately those cases that successfully can be treated by marginal resection. It was felt that invasion of medullary bone would be a contraindication to marginal resection since tumour spread in medullary bone can be rapid and extensive. However, localised tumour invasion of cortical bone only, may not be a contraindication to marginal resection, particularly if this spread can be accurately delineated by means of CT or MRI scanning. It was also felt that by using these imaging techniques for more accurate localisation of tumours, some tumours might be resected via a purely’intraoral approach utilising the techniques and instrumentation from orthognathic surgery. Materials and methods Thirteen consecutive patients with biopsy-proven Tl or T2; NO; M,, squamous cell carcinomas of the mandibular alveolar mucosa and associated structures and a negative panoral radiograph were included in this study. All patients received a radioisotope scan of the mandible, using a phosphate isotope of technetium. All of the patients also received either a CT scan of the mandible or a MRI scan of the mandible, depending on when the investigations were carried out since MRI scanning did not become generally available until 1984. Three patients received both a CT scan and MRI scan. The results of these investigations were analysed,
Figure 2-CT
Fig. 2 scan showing extensive medullary and cortical bone involvement by tumour (arrowed) despite negative panoramic radiograph.
TREATMENT
OF
MANDIBULAR
TUMOURS
135
and as a consequence, patients showing no bone invasion, or invasion limited to cortical bone only, received a marginal mandibulectomy; whereas patients showing more extensive bone involvement received segmental resection. All patients have been followed up for a minimum of 2 years and the longest follow-up is now 7 years. A Results Of the 13 patients involved, none showed unequivocal bone involvement on panoramic radiography. Nine patients showed hot spots on isotope bone __ scanning (Fig. 1) but following resection, there was histological tumour invasion of bone in only seven cases. This confirms that isotope bone scanning is a very sensitive but nonspecific investigation with poor definition. Positive results can result from infection and inflammation as well as tumour involvement. Two cases, which showed no bone involvement on panoramic radiography, showed extensive cortical and medullary bone involvement on CT scanning (Fig. 2) and they were therefore excluded from this study and underwent segmental resection. In a further four cases, the CT scan showed cortical bone invasion but no medullary bone invasion. Of the patients who underwent MRI scanning, two patients showed cortical bone invasion by tumour (Fig. 3) but none showed medullary bone invasion. One of the patients with cortical bone involvement had both MRI and CT scanning and in this case, both the CT and MRI showed good correlation. On the MRI scan, cortical bone, which contains relatively little water shows as a black filling defect, whereas medullary bone and surrounding soft tissues, which contain more water, show as white or grey areas. Following preliminary scanning, the 11 remaining patients (after exclusion of the two patients showing medullary bone invasion) underwent marginal resection of their tumours. Nine of the patients underwent the procedure from an extraoral
Figure 3-MRI
scan showing invasion of cortical bone (black) by tumour (arrowed) despite negative panoramic radiograph.
Compare right and left sides.
136
BRITISH
JOURNAL
OF
ORAL
&
MAXILLOFACIAL
SURGERY
Fig. 4 Figure 4-Squamous cell carcinoma of left buccal alveolus involving periodontal ligament. Tumour recurred postoperatively probably due to medullary bone involvement via the periodontal ligament.
approach, but in two cases, the excision could be carried out intraorally. Seven of the 11 patients received postoperative radiotherapy, varying between 6 000 and 7 200 cGy to the effected area. In all cases, radiation consisted of photon therapy via at least two opposing ports. Five of the seven patients also received elective photon irradiation of the ipsilateral neck. In no cases to date has there been any pathological fracture or evidence of osteoradionecrosis. Histological examination of resected specimens showed 100% correlation between MRI and CT, scans and bone invasion in that the CT scans accurately identified medullary bone invasion in two cases and CT and/or MRI scan accurately showed cortical bone invasion in a further five cases. To date (shortest follow-up 2 years, longest follow-up 7 years), there has been one recurrence. This was in a 63 year-old male with a carcinoma of the buccal alveolar mucosa in the lower left second molar area (Fig. 4) in whom the initial biopsy showed invasion of the periosteum and tumour lying adjacent to the periodontal membrane of the second molar. The CT scan did not show any bone invasion but unfortunately it lacked some definition in the appropriate area due to radiation scatter from some gold restorations. Despite the fact that the resected specimen had histologically clear margins, a recurrence occurred at the anterior end of the marginal resection 11 months after initial surgery despite the patient having had 7 000 cGy of postoperative photon radiation. Subsequent segmental resection plus a suprahyoid neck dissection (no positive nodes were found clinically or histologically) was carried out; and the patient remains well 18 months later. Discussion
These 13 cases show that by accurate delineation of the extent of tumour spread by means of CT scans and magnetic resonance imaging, it may be possible on
TREATMENT
OF
MANDIBULAR
TUMOURS
137
occasion, to resect malignant tumours involving only cortical bone of the mandible thereby preserving mandibular continuity in that portion of the mandible most distant from the tumour. The advantages in terms of cosmesis and function, combined with irradication of malignancy can make the procedure extremely beneficial. This surgery is carried out utilising the instruments and techniques developed for orthognathic surgery. Frequently, this surgery can be carried out from a purely intraoral approach, avoiding the additional morbidity of an extraoral scar. Though criteria have not formally been established for those tumours most suitable for marginal resection, it would appear that only T-l and possibly T-2 tumors are suitable. Lymph node spread is not a contraindication, but it does mean that an in continuity en bloc resection will be necessary from an extraoral approach. This may well require a pull-through type of procedure, possibly including resection of the lingual plate of the mandible. Since many cases will require there is some concern that if excessive postoperative radiation treatment, periosteum is stripped from the remaining marginal strut of the inferior border of the mandible, its vitality may be in question rendering it susceptible to osteoradionecrosis (Converse, 1977). Although this is a legitimate concern, very few cases of osteoradionecrosis have been described in the inferior border strut of mandible. It may well be that the covering soft tissue is sufficiently well vascularised, to make osteoradionecrosis a rare complication. There were no cases to date of osteoradionecrosis in the seven cases in this study which received postoperative radiotherapy. The degree of bone involvement with tumours of the alveolar and related mucosa appear to be fairly low. In a study of 104 cases, Gilbert et al. found that 22% had histological evidence of bone involvement (Gilbert et al., 1986). The presence or absence of neck nodes did not affect the result. Radiographs and bone scans help, although false positives occurred with both modalities. There were no false negatives with bone scans which are’s more sensitive indicator of bone turnover than radiographs. Similar figures for bone involvement have been observed in other studies, Slaughter (1949) 29%) Lampe (1955) and Panagopoulas (1959) 25%. The size of the tumour does not appear to influence the incidence of bone involvement but the proximity of the tumour to bone does have a relationship and tumours involving the gingival margin appear to have a particularly high incidence of bone involvement. In the present study, CT scan, MRI and histology showed bone involvement in 7 out of 13 cases (54%) though panoral radiographs were negative. In the one case where recurrence occurred, tumour probably gained access to the cancellous bone via the periodontal membrane. At the present time, it is felt that periodontal membrane involvement is a contraindication to marginal mandibulectomy as is any other evidence of cancellous bone involvement. With the increasing use of elective postoperative irradiation of the neck and surrounding areas, the rationale for a marginal resection from an intraoral approach supplemented by postoperative radiation therapy, if appropriate, may become more firmly established. Functionally, a delayed inferior alveolar nerve repair is often feasible, as is prosthetic rehabilitation so that a number of patients can be dentally rehabilitated subsequently. Although the number of patients in this study is too small to draw any significant conclusions, the two-year cure rates are encouraging enough to continue the study of marginal mandibulectomy for Ti and T2 carcinomas of the mandibular alveolar mucosa which may involve the cortical bone only.
138
BRITISH JOURNAL
OF
ORAL
& MAXILLOFACIAL
SURGERY
References
Beecroft, W. A., Sako, K. & Razack, M. S. (1982). Mandible preservation in the treatment of cancer of the floor of the mouth. Journal of Surgical Oncology, 19, 171. Byers, R. M., Newman, R. & Russell, N. (1981). Results of treatment for squamous cell carcinoma of the lower gum. Cancer, 47, 2236. Converse, J. M. (1977). Reconstructive Plastic Surgery. Volume 5, pp. 2690-2692. W.B. Saunders Co. Fletcher, G. H. (1972). Elective irradication of subclinical disease in cancers of the head and neck. Cancer,
29, 1450.
Gilbert, S., Tzadik, A. & Leonard, G. (1986). Mandibular involvement by oral squamous cell carcinoma. Laryngoscope, 96, 96. Lampe, I. (1955). Radiation therapy of cancer of the buccal mucosa and lower gingivae. American Journal
of Roentgenology,
73, 628.
McGregor, I. A. & McGregor, F. M. (1986). Cancer of the mouth. pp. 5-54. Edinburgh: Churchill Livingstone. Marchetta, F. C., Sako, K. & Murphy, J. B. (1971). The periosteum of the mandible and intraoral carcinoma. American Journal of Surgery, 122, 711. Mattick, W. L. & Meehan, D. .I. (1951). Cancer of the gum. Surgery, 29, 249. Morrish, R. B., Chan, E., Silverman, S., Meyer, J., Fu, K. K. & Greenspan, D. (1981). Osteoradionecrosis in patients irradiated for head and neck carcinoma. Cancer, 47, 1980. Nahum, A. M., Bone, R. C. & Davidson, T. M. (1976). The case of elective prophylactic neck dissection. Transactions of American Academy of Opthalmology and Otolaryngology, 82, 603. Panagopoulas, A. P. (1959). Bone involvement in maxillofacial cancer. American Journal of Surgery, 98, 890.
Quick, D. (1926). Carcinoma of the lower jaw. American Journal of Surgery, 1, 360. Slaughter, D. P., Roesser, E. N. & Smejkal, W. F. (1949). Excision of the mandible for neoplastic disease. Surgery, 26, 507. Wald, R. M., Caliaterra, T. C. (1951). Lower alveolar carcinoma. Arch Otolaryngology, 109, 578. Ward, G. W. & Robben, J. 0. (1951). Composite operation for radical neck dissection and removal of cancer of the mouth. Cancer, 4, 98.
0266 4356Xl89/0027-0132/$10.00
THE MARGINAL MANDIBULECTOMY FOR THE TREATMENT OF MANDIBULAR TUMOURS M. A. POGREL, M.B., ch.B.,B.D.s.,F.D.s.R.c.s., F.R.C.S. The Division of Oral and Maxillofacial Surgery, San Francisco
The University of California,
Summary. With the knowledge and techniques gained from orthognathic surgery and more precise imaging techniques, it has become more practical to carry out rim or marginal resections for some malignant tumours of the alveolus to preserve mandibular continuity and yet have adequate tumour margins. This is of great functional and cosmetic importance to the patient. A study of 11 patients is presented to analyse criteria for carrying out this procedure.
Introduction Since the 1940’s, malignant disease of the mandible, mandibular alveolar mucosa and related lingual and buccal mucosa, primarily has been managed surgically, since radiation in close proximity to the mandible runs a significant risk of precipitating osteoradionecrosis (Morrish et al., 1981). Furthermore, radiotherapy as primary treatment is often ineffective in controlling lesions involving the mandible (Quick, 1926; Mattick & Meehan, 1951; Lampe, 1955). Radiation is, however, often given as a combined therapy with surgery. The traditional surgical approach to these lesions involves a composite resection of the mandible and associated soft tissues. This is frequently carried out in continuity with a radical neck dissection or modified neck dissection if there are clinically involved nodes or if the incidence of occult nodes is felt to justify this treatment (Slaughter et al., 1949). Nahum et al. (1976) present an excellent review of the case for and against elective neck dissection and conclude that there is no factual basis for the procedure. Elective irradiation of the neck (Fletcher, 1982) is a preferable modality if required, in most instances. Segmental resection of the mandible allows easy access to the tumour bed and can facilitate primary soft tissue closure. Yet, the problems of reconstruction and rehabilitation following this form of surgery are considerable. Though some people appear to be able to function fairly well without a portion of mandible and others can tolerate the cosmetic deformity, in many cases reconstruction is necessary. To date, a purely prosthetic approach utilising meta!lic or other implants has not met with long term success. To achieve successful reconstruction, both bone and soft tissue must be used, and though free bone grafts and soft tissue flaps can be used, many surgical techniques now utilise myocutaneous and osteomyocutaneous flaps. There are a wide variety of such pedicled or free flaps which have been utilised for mandibular reconstruction, but they all have associated problems (McGregor & McGregor, 1986). In recent years a small number of studies have examined the feasibility of carrying out a marginal resection of the mandible for alveolar carcinoma, preserving a rim of the inferior or lateral border of the mandible, with obvious functional and cosmetic advantages (Converse, 1977; Beecroft et al., 1982; Wald & Caliaterra, 1983; Gilbert et al., 1986; McGregor & McGregor, 1986). These studies (Received
7 January
1988; accepted 30 April 1988)
132
TREATMENT
OF MANDIBULAR
TUMOURS
133
vary considerably in terms of patient selection and treatment modalities, since there are a variety of combinations of local resection plus or minus associated radical neck dissection and possibly combined with radiotherapy. However, they do appear to show that in selected cases similar success rates can be obtained with a marginal resection of the mandible preserving the lower border as opposed to a more conventional segmental resection removing the whole thickness of the mandible. One argument which has been given against marginal resection of the mandible is that the lymphatic drainage from the alveolus and the floor of the mouth passes on the lingual periosteum and that if this is not fully resected in continuity with the tumour, recurrence is likely (Ward & Robben, 1951). It has been shown, however, that these lymphatics do not lie on the lingual periosteum and that this periosteum can often be spared (Marchetta et al., 1971). Even when the periosteum must be resected, the specimen is removed in continuity with the lingual plate and the remaining mandible left in situ. Criteria have been formulated to define those tumours which may be suitable for marginal resection of the mandible. It appears that T-l and T-2 tumors may be suitable, with similar cure rates for marginal or segmental resection in both Stage I and Stage II disease (Byers et al., 1981). To be suitable for marginal resection, it has also been suggested that there should be no preoperative evidence of bone involvement and no perineural involvement as determined by plain radiographs and clinical examination. The tumour may extend through to periosteum but
Fig. I Figure l-Area
of increased uptake on TcW polyphosphate bone scan in left anterior mandible (arrowed). Specimen confirmed tumour invasion in same area.
134
BRITISH
JOURNAL
OF
ORAL
&
MAXILLOFACIAL
SURGERY
should not involve bone (Wald & Caliaterra, 1983). Studies on marginal resection of the mandible have generally described this as being performed from an extraoral approach which often includes a lip-splitting technique. Because earlier criteria for marginal resection were based on clinical examination and plain radiographs, it was felt that modem imaging techniques such as radioisotope imaging, CT scanning and magnetic resonance imaging (MRI) studies may help to delineate more accurately those cases that successfully can be treated by marginal resection. It was felt that invasion of medullary bone would be a contraindication to marginal resection since tumour spread in medullary bone can be rapid and extensive. However, localised tumour invasion of cortical bone only, may not be a contraindication to marginal resection, particularly if this spread can be accurately delineated by means of CT or MRI scanning. It was also felt that by using these imaging techniques for more accurate localisation of tumours, some tumours might be resected via a purely’intraoral approach utilising the techniques and instrumentation from orthognathic surgery. Materials and methods Thirteen consecutive patients with biopsy-proven Tl or T2; NO; M,, squamous cell carcinomas of the mandibular alveolar mucosa and associated structures and a negative panoral radiograph were included in this study. All patients received a radioisotope scan of the mandible, using a phosphate isotope of technetium. All of the patients also received either a CT scan of the mandible or a MRI scan of the mandible, depending on when the investigations were carried out since MRI scanning did not become generally available until 1984. Three patients received both a CT scan and MRI scan. The results of these investigations were analysed,
Figure 2-CT
Fig. 2 scan showing extensive medullary and cortical bone involvement by tumour (arrowed) despite negative panoramic radiograph.
TREATMENT
OF
MANDIBULAR
TUMOURS
135
and as a consequence, patients showing no bone invasion, or invasion limited to cortical bone only, received a marginal mandibulectomy; whereas patients showing more extensive bone involvement received segmental resection. All patients have been followed up for a minimum of 2 years and the longest follow-up is now 7 years. A Results Of the 13 patients involved, none showed unequivocal bone involvement on panoramic radiography. Nine patients showed hot spots on isotope bone __ scanning (Fig. 1) but following resection, there was histological tumour invasion of bone in only seven cases. This confirms that isotope bone scanning is a very sensitive but nonspecific investigation with poor definition. Positive results can result from infection and inflammation as well as tumour involvement. Two cases, which showed no bone involvement on panoramic radiography, showed extensive cortical and medullary bone involvement on CT scanning (Fig. 2) and they were therefore excluded from this study and underwent segmental resection. In a further four cases, the CT scan showed cortical bone invasion but no medullary bone invasion. Of the patients who underwent MRI scanning, two patients showed cortical bone invasion by tumour (Fig. 3) but none showed medullary bone invasion. One of the patients with cortical bone involvement had both MRI and CT scanning and in this case, both the CT and MRI showed good correlation. On the MRI scan, cortical bone, which contains relatively little water shows as a black filling defect, whereas medullary bone and surrounding soft tissues, which contain more water, show as white or grey areas. Following preliminary scanning, the 11 remaining patients (after exclusion of the two patients showing medullary bone invasion) underwent marginal resection of their tumours. Nine of the patients underwent the procedure from an extraoral
Figure 3-MRI
scan showing invasion of cortical bone (black) by tumour (arrowed) despite negative panoramic radiograph.
Compare right and left sides.
136
BRITISH
JOURNAL
OF
ORAL
&
MAXILLOFACIAL
SURGERY
Fig. 4 Figure 4-Squamous cell carcinoma of left buccal alveolus involving periodontal ligament. Tumour recurred postoperatively probably due to medullary bone involvement via the periodontal ligament.
approach, but in two cases, the excision could be carried out intraorally. Seven of the 11 patients received postoperative radiotherapy, varying between 6 000 and 7 200 cGy to the effected area. In all cases, radiation consisted of photon therapy via at least two opposing ports. Five of the seven patients also received elective photon irradiation of the ipsilateral neck. In no cases to date has there been any pathological fracture or evidence of osteoradionecrosis. Histological examination of resected specimens showed 100% correlation between MRI and CT, scans and bone invasion in that the CT scans accurately identified medullary bone invasion in two cases and CT and/or MRI scan accurately showed cortical bone invasion in a further five cases. To date (shortest follow-up 2 years, longest follow-up 7 years), there has been one recurrence. This was in a 63 year-old male with a carcinoma of the buccal alveolar mucosa in the lower left second molar area (Fig. 4) in whom the initial biopsy showed invasion of the periosteum and tumour lying adjacent to the periodontal membrane of the second molar. The CT scan did not show any bone invasion but unfortunately it lacked some definition in the appropriate area due to radiation scatter from some gold restorations. Despite the fact that the resected specimen had histologically clear margins, a recurrence occurred at the anterior end of the marginal resection 11 months after initial surgery despite the patient having had 7 000 cGy of postoperative photon radiation. Subsequent segmental resection plus a suprahyoid neck dissection (no positive nodes were found clinically or histologically) was carried out; and the patient remains well 18 months later. Discussion
These 13 cases show that by accurate delineation of the extent of tumour spread by means of CT scans and magnetic resonance imaging, it may be possible on
TREATMENT
OF
MANDIBULAR
TUMOURS
137
occasion, to resect malignant tumours involving only cortical bone of the mandible thereby preserving mandibular continuity in that portion of the mandible most distant from the tumour. The advantages in terms of cosmesis and function, combined with irradication of malignancy can make the procedure extremely beneficial. This surgery is carried out utilising the instruments and techniques developed for orthognathic surgery. Frequently, this surgery can be carried out from a purely intraoral approach, avoiding the additional morbidity of an extraoral scar. Though criteria have not formally been established for those tumours most suitable for marginal resection, it would appear that only T-l and possibly T-2 tumors are suitable. Lymph node spread is not a contraindication, but it does mean that an in continuity en bloc resection will be necessary from an extraoral approach. This may well require a pull-through type of procedure, possibly including resection of the lingual plate of the mandible. Since many cases will require there is some concern that if excessive postoperative radiation treatment, periosteum is stripped from the remaining marginal strut of the inferior border of the mandible, its vitality may be in question rendering it susceptible to osteoradionecrosis (Converse, 1977). Although this is a legitimate concern, very few cases of osteoradionecrosis have been described in the inferior border strut of mandible. It may well be that the covering soft tissue is sufficiently well vascularised, to make osteoradionecrosis a rare complication. There were no cases to date of osteoradionecrosis in the seven cases in this study which received postoperative radiotherapy. The degree of bone involvement with tumours of the alveolar and related mucosa appear to be fairly low. In a study of 104 cases, Gilbert et al. found that 22% had histological evidence of bone involvement (Gilbert et al., 1986). The presence or absence of neck nodes did not affect the result. Radiographs and bone scans help, although false positives occurred with both modalities. There were no false negatives with bone scans which are’s more sensitive indicator of bone turnover than radiographs. Similar figures for bone involvement have been observed in other studies, Slaughter (1949) 29%) Lampe (1955) and Panagopoulas (1959) 25%. The size of the tumour does not appear to influence the incidence of bone involvement but the proximity of the tumour to bone does have a relationship and tumours involving the gingival margin appear to have a particularly high incidence of bone involvement. In the present study, CT scan, MRI and histology showed bone involvement in 7 out of 13 cases (54%) though panoral radiographs were negative. In the one case where recurrence occurred, tumour probably gained access to the cancellous bone via the periodontal membrane. At the present time, it is felt that periodontal membrane involvement is a contraindication to marginal mandibulectomy as is any other evidence of cancellous bone involvement. With the increasing use of elective postoperative irradiation of the neck and surrounding areas, the rationale for a marginal resection from an intraoral approach supplemented by postoperative radiation therapy, if appropriate, may become more firmly established. Functionally, a delayed inferior alveolar nerve repair is often feasible, as is prosthetic rehabilitation so that a number of patients can be dentally rehabilitated subsequently. Although the number of patients in this study is too small to draw any significant conclusions, the two-year cure rates are encouraging enough to continue the study of marginal mandibulectomy for Ti and T2 carcinomas of the mandibular alveolar mucosa which may involve the cortical bone only.
138
BRITISH JOURNAL
OF
ORAL
& MAXILLOFACIAL
SURGERY
References
Beecroft, W. A., Sako, K. & Razack, M. S. (1982). Mandible preservation in the treatment of cancer of the floor of the mouth. Journal of Surgical Oncology, 19, 171. Byers, R. M., Newman, R. & Russell, N. (1981). Results of treatment for squamous cell carcinoma of the lower gum. Cancer, 47, 2236. Converse, J. M. (1977). Reconstructive Plastic Surgery. Volume 5, pp. 2690-2692. W.B. Saunders Co. Fletcher, G. H. (1972). Elective irradication of subclinical disease in cancers of the head and neck. Cancer,
29, 1450.
Gilbert, S., Tzadik, A. & Leonard, G. (1986). Mandibular involvement by oral squamous cell carcinoma. Laryngoscope, 96, 96. Lampe, I. (1955). Radiation therapy of cancer of the buccal mucosa and lower gingivae. American Journal
of Roentgenology,
73, 628.
McGregor, I. A. & McGregor, F. M. (1986). Cancer of the mouth. pp. 5-54. Edinburgh: Churchill Livingstone. Marchetta, F. C., Sako, K. & Murphy, J. B. (1971). The periosteum of the mandible and intraoral carcinoma. American Journal of Surgery, 122, 711. Mattick, W. L. & Meehan, D. .I. (1951). Cancer of the gum. Surgery, 29, 249. Morrish, R. B., Chan, E., Silverman, S., Meyer, J., Fu, K. K. & Greenspan, D. (1981). Osteoradionecrosis in patients irradiated for head and neck carcinoma. Cancer, 47, 1980. Nahum, A. M., Bone, R. C. & Davidson, T. M. (1976). The case of elective prophylactic neck dissection. Transactions of American Academy of Opthalmology and Otolaryngology, 82, 603. Panagopoulas, A. P. (1959). Bone involvement in maxillofacial cancer. American Journal of Surgery, 98, 890.
Quick, D. (1926). Carcinoma of the lower jaw. American Journal of Surgery, 1, 360. Slaughter, D. P., Roesser, E. N. & Smejkal, W. F. (1949). Excision of the mandible for neoplastic disease. Surgery, 26, 507. Wald, R. M., Caliaterra, T. C. (1951). Lower alveolar carcinoma. Arch Otolaryngology, 109, 578. Ward, G. W. & Robben, J. 0. (1951). Composite operation for radical neck dissection and removal of cancer of the mouth. Cancer, 4, 98.