Ⅰ. INTRODUCTION
Worldwide, oral cancer accounts for 2%–4% of all cancer cases. It is estimated that more of 90% of all oral neoplasms are oral squamous cell carcinoma (OSCC) [1,2]. Advancedstage oral cavity malignancies require combined modality therapy, and patients typically undergo surgical resection followed by adjuvant radiation with or without chemo- therapy [3]. The surgical approach to primary site of the oral cavity is dictated by the size and location of the tumor and the anatomic region involved relative to the tumor's presentation [4].
After resection at the mandibular body site involving oral cancer, free vascularized fibular graft, a type of vascularized autograft, is often used for the mandibular reconstruction [5]. Also, according to defect condition, titanium mesh (T-mesh) and particulate cancellous bone and marrow (PCBM), and a type of non-vascularized autograft also can be used for the reconstruction.
The aims of this study were to evaluate follow-up outcomes with pathologic reviews in patients with OSCC invading the mandibular bone who underwent primary radical and reconstructive surgery. We obtained ethics approval (IRB No. PNUDH-2020-034) from PNUDH for this case report.
In this article, we report two case of patients with OSCC invading the mandibular bone. A 68-year-old male patient had OSCC on the mandible left gingiva and bone area and underwent surgical procedures, such as wide excision of the site and reconstruction with fibula free flap. The other patient is a 51-year-old female patient who had OSCC on the mandible right area and underwent follow-up sequential surgical procedures like CAD-CAM T-mesh reconstruction. Additionally, some literature will serve as evidence for our treatment of the patient.
Ⅱ. Case Presentation
CASE 1.
A 68-year-old male patient visited to Pusan National University Dental Hospital due to a left mandibular gingiva swelling and pain. Upon clinical examination at our clinic, a ulcerative whitish swelling lesion was observed in left mandibular gingiva (Fig. 1 A), Furthermore, the panoramic examination revealed, and bone erosion on the mandible left alveolar bone area and indeterminate lymph node on left level II was observed on CT enhance (Fig. 1 B, C). To check of general condition, laboratory testing including a complete blood count, electrolyte, liver, and renal function chemistries, total protein, albumin, quantitative im- munoglobulin, lactate dehydrogenase (LDH), erythrocyte sedimentation rate, ferritin, uric acid, and urinalysis was performed. The patient had hypertension only as pre-existing general disease and no alcohol drinking or smoking history.
A dentist suspected any malignancy lesion on the mandibular left gingival and alveolar bony area, and performed incisional biopsy, additional MRI, and PET for an accurate diagnosis. The results of incisional biopsy revealed moderate differentiated histologic type of squamous cell carcinoma. And MRI views show a lesion involving mandible left bone and lingual gingival area (Fig. 1 D) and the border of the lesion is relatively precisely destroyed. The Fluorine-18-fluorodeoxyglucose positron emission tomography/ computed tomography (F18-FDGPET/CT) was performed, which also give an information about SUVmax 14.4 and no other metastatic organ like lung. After that, the surgeon seriously considered wide ablation about lingual gingival OSCC area and transplantation of fibular bone on mandibular bone resection area for function and quality of patient life.
The surgical team planned nasotracheal intubation wide excision, segmental mandibulectomy, supra-omo-hyoid neck dissection (SOHND), and reconstruction with fibular free flap, which is considered of the radiological and clinical findings. Surgery design was done by using rapid prototyping (RP) model and resin block. Surgery was done on June 2020 (Fig. 2 A). During operation, left fibular free flap was harvested (Fig. 2 B). The size of the removed primary main mass with a safety margin was 6.5 x 4.3 x 2.8 cm (Fig. 3 A, B), after surgery the pathologic result give resection OSCC margin is clear. Also, the excised lymph node specimen was 4.5 x 1.2 x 0.7 cm (Fig. 3 C), unfortunately the surgeon can prove two level II lymph node was metastasis by pathologic result. The mandibular resection defect was successfully anastomosed with fibular free flap (Fig. 2 C) using superior thyroid artery and branch of jugular veins as recipient vessels and covered without any tension or complications. The excised specimen was examined. Histological examination revealed squamous cell carcinoma and level IIa metastatic lymph node (Fig. 4 B). Furthermore, the resection margin of the main specimen was clear (Fig. 4 A). Post-operative chemo radiation therapy was done, 6 weeks after the diagnosis of the malignancy and operation, because of metastatic lymph node on surgical specimen.
Mandibular left gingival area, neck, and left leg were observed by clinically and radiographically 1 months after the surgery (Fig. 2 D). Complete healing was noted within 6 weeks. The defect was completely covered without any complications. The main professor observed carefully the patient’s operative site and general condition.
CASE 2.
The other case is a 51-year-old female patient who referred to Pusan National University Dental Hospital in 2016. The patient had done clinical examination, an ulcerative lesion and bone exposure was observed in right mandibular gingiva (Fig. 5 A), Furthermore, the panoramic examination (Fig. 5 B) revealed, and bone destruction on the mandible right and 4.1 x 1.8 x 2.5 cm sized lesion was observed on MR T2 views (Fig. 5 C, D). Laboratory testing was performed for check of general condition. The patient had hypertension and Parkin’s disease as pre-existing general disease and no alcohol drinking or smoking history.
The patient was operated wide excision, segmental mandibulectomy, supra-omohyoid neck dissection (SOHND), and reconstruction with fibular free flap through incisional biopsy, additional CT enhancement, MRI, and PET in July 2016. The histopatholgical examination displayed that the tumor mass mainly consists of spindle-shaped cells with focal foci of squamous differentiations, moderate dysplasia and multiple blood vessels. In addition, the tumor cells invade surrounding connective tissue. There are neither lymphatic/ venous invasion nor perineural invasion. The resection margins of the specimen were clear and there were no metastasis in the resected lymph nodes. Curettage, mini plate removal, and fibular bone debridement were per- formed in December 2017 after follow-up due to an infection of the flap that occurred within 1 month after surgery (Fig. 6 A) but the biopsy result was revealed clear safety margin and no metastatic lymph node (Fig. 6 B).Close observation was done until January 2020 without post-operative CCRT due to no lymph node involvement post operatively, after confirming no recurrence, titanium mesh (T-mesh) (Fig. 7 A, B, C) and particulate cancellous bone and marrow (PCBM) of iliac bone, a type of non-vascularized autograft were performed (Fig. 7). After second reconstruction, jaw function and quality of patient life was recovered.
Ⅲ. DISCUSSION
OSCC invading the mandibular body bone have to be considered about primary radical and reconstructive surgery because of patient’s quality of life and survival rate. Despite the advances of therapeutic approaches, percentages of morbidity and mortality of OSCC have not improved significantly during the last 30 years. Percentages of morbidity and mortality in males are 6.6/100,000 and 3.1/100,000 respectively, while in females the same percentages are 2.9/100,000 and 1.4/100,000 [6]. The percentage of 5-year survival for patients with OSCC varies from 40-50% [1]. Considering these factors, it is judged that a long-term protocol considering various factors is needed for the treatment of patients who need reconstruction in the mandible body advanced OSCC.
The incidence of oral cancer is 2%–4% and more of 90% of all oral neoplasms are OSCC. It is said that differential diagnosis and additional follow-up have become easier due to intraoral examination, but until recently, there are many patients who need treatment according to surgery and systematic protocol due to advanced type oral cancer. With considering of evaluation of the patient's various systemic conditions, the histological differentiation of the margin of the main mass, the lymph node metastasis, and x-ray such as CT, MRI and PET, there is a need to establish a systematic surgical protocol.
If there is OSCC, it is necessary to attain optimal surgical tumor-free margin to avoid local recurrence and improve survival. Also, if that OSCC involved in bone, it is T4 advanced type and needed to have segmental mandibulectomy instead of marginal mandibulectomy. Even though a tumor-free resection surface does not guarantee that local recurrence will not occur [7], before reconstruction in the middle of the surgical procedure, we must go through the frozen biopsy to confirm during operation that the surgical margin is clean. In the literature, close surgical margins less than 3 mm or 5 mm have been reported to be associated with a high risk of cancer recurrence. However, there is still no universally agreed definition of close surgical margin [8]. As many techniques are available, depending upon the feasibility, a correct method has to be followed by a surgeon for complete clearance of the surgical margins to reduce the chances of recurrence [9]. In the first patient, the surgical margin was relatively clear and the pathologic subtype were moderately differentiated. But, metastatic Level II lymph nodes were found. The other case was different on pathologic subtype, margin and involved metastatic lymph node existence. These are very important factors in determining CCRT after surgery.
More recently, selective neck dissection has been developed in order to reduce the morbidity of radical neck dissection [10]. Maintaining method of the airway after operation according to the surgical resection margin and the neck dissection can be considered before surgery. Surgical tracheostomy is essential for the postoperative care when swelling and edema can lead to airway compromise. The decision to perform planned intra-operative tracheostomy is based on the extent of surgery, likelihood of further postoperative swelling, and the ability to rescue the airway [11]. Nasotracheal tube can be maintained for couple of post-operative days when tracheostomy doesn’t need. The Nastracheal intubation was done in the one case, the tracheostomy was done in the other case, in this report. Tracheostomy was performed when it was judged that after surgery dyspnea due to postoperative swelling was serious considering because of the location of the lesion.
Resection area should be reconstructed, our one case had done by fibular free flap, and T-mesh with PCBM. Sufficient new-bone formation was observed in terms of volume and strength. In the CAD-CAM custom-made type T-mesh case (Cusmedi, S. Korea), especially, it was much easier to fix screws onto the adjacent mandible, and after the removal of the mesh, the appearance of both patients was improved, and the neo-mandibular body showed adequate bony volume for implant or prosthetic restoration like our other report [5].
After surgery, surgeon carefully consider with post-operative radiotherapy and chemotherapy. In radiotherapy, important parameters include close (<5 mm) or positive margins, tumor extension through the lymph node capsule, invasion of the soft tissues of the neck, more than 5 mm subglottic invasion, two or more positive lymph nodes, perineural invasion and endothelial-lined space invasion [12-13].
Efforts to increase the efficacy of radiotherapy, especially in local advanced disease, include, altered fractionated radiotherapy or concomitant chemo-radiotherapy (CCRT) [14]. Furthermore, as for chemotherapy, cisplatin-based chemoradiation remains the standard for locoregionally advanced head and neck SCC [15]. The treatment of choice for the localized lesions is surgical excision with a clear margin. Chemotherapy and radiation therapy should also be considered as treatment options for neck node metastatic lesions. In this cases, post-operative CCRT was determined by proven theory such as pathologic free margin involvedness and subtype, and lymph node metastasis.
If at least some of the malignant tendencies are known at the time of the initial diagnosis, clinical examination, and radiographic imaging, radiologists and the surgeons need to actively cooperate in order to establish proper diagnosis and treatment plan.
Ⅳ. CONCLUSION
The aim of this study was to evaluate outcome of surgery options and adjunctive postoperative radiation therapy in patients with OSCC invading the mandibular bone (T4) who underwent primary radical mandibulectomy with neck lymph node dissection for removal of occult metastasis of cancer cells and immediate reconstructive surgery with free vascularized bone flaps or PCBM to improve the function of maxillofacial area after surgery.
