[Mass Screening of Oral Cancer in Eastern Shimane Prefecture during 2015-2019].

The Department of Oral and Maxillofacial Surgery, Shimane University Faculty of Medicine, has been conducting mass screening of oral cancer using oral abrasion cytology by oral surgeons in eastern Shimane prefecture for public awareness and its early detection. As a result, 3(0.09%)cases of oral cancer were identified. Case 1: The patient was diagnosed with well-differentiated squamous cell carcinoma in the floor of the mouth(pT1N0M0, Stage Ⅰ)after undergoing Matsue city oral cancer screening in 2016. Case 2: The patient underwent oral cancer screening in Izumo city in 2018 and was diagnosed with verrucous carcinoma in the back of the tongue(pT1N0M0, Stage Ⅰ). Case 3: The patient was diagnosed with highly differentiated squamous cell carcinoma of the palate(pT1N0M0, Stage Ⅰ)after undergoing the Izumo city oral cancer screening in 2019. Awareness of oral cancer is important, and cancer screening by oral surgeons using cytology is highly useful and should be continued in the future.

[A Case of Treatment Applicable to Squamous Cell Carcinoma of the Tongue by Mass Screening Examination of Oral Cancer in Western Part of the Shimane Prefecture].

Radical excision, a common oral cancer treatment, produces variable postoperative results depending on the specialized tissues involved and the extent of the cancer. Furthermore, the material selected for reconstruction also influences functional outcomes. Oral dysfunction due to postoperative tissue loss is more common with advanced cancer; therefore, early detection and treatment are important. To improve oral cancer awareness and early detection, mass oral cancer screenings led by maxillofacial surgeons in cooperation with the Shimane prefecture and local dental associations were conducted. We describe the mass screening methods and describe a case of tongue cancer that was detected and treated as a result of our screening efforts.

[Effective Treatment of Ameloblastoma in an Odontogenic Cyst with Fenestration before Curative Surgery-A Case Report].

Ameloblastoma is a benign odontogenic tumor that rarely undergoes malignant transformation and metastasis but may be locally invasive and recurrent. Fenestration is used to reduce maxillary odontogenic cysts. Here, we report a case ofameloblastoma that developed in the wall of an odontogenic cyst and was treated with fenestration before curative surgery. A 57-yearold Japanese man presented with a mass on the right side ofthe lower gingiva. Computed tomography revealed a unicystic lesion in the right mandibular body, accompanied by a multicystic area in the right lower canine region. Three involved molars were extracted and the cystic wall was harvested. Biopsy analysis revealed an odontogenic cyst in the unicystic lesion and an ameloblastoma in the multicystic area. The ameloblastoma was thought to have developed in the odontogenic cyst wall. The biopsy wound was maintained as a fenestration for 3 months and the lesion was reduced. Marginal resection of the mandible with cystectomy was performed to preserve mandibular bone continuity and the mandibular nerve. Although fenestration delayed curative surgery, the large cystic lesion reduction helped to avoid complications after curative surgery.

[Feasibility of a Heart-Shaped Modified Pectoralis Major Myocutaneous Flap for a Stabilized Vascular Supply in the Reconstruction of Surgically Induced Defects in Patients with Advanced Oral Cancer].

The pedicled pectoralis major myocutaneous(PMMC)flap, used for the reconstruction of surgical defects in advanced oral cancer resection, is versatile and can be obtained without a highly-invasive procedure. However, flap utility is limited by an unstable blood supply and the relatively high rate of partial necrosis of the skin island. Thus, the use of microvascularized free flaps has become more common in patients requiring oral-maxillofacial reconstruction. Detailed angiographic studies revealed the 3-dimensional vascular anatomy of the PMMC flap. This allowed us to obtain a modified, heart-shaped flap with a skin island that includes the intramuscular vascular networks between the pectoral branches of the thoracoacromial vessels and the intercostal perforators of the internal mammary vessels, thus ensuring a sufficient blood supply and stable survival of the flap. We have used this technique since 2015 to treat 7 patients with locally advanced or recurrent(salvage)oralcancer. None developed critical flap problems, and survival of the total skin island was successfully obtained in all cases. Transfer of the heart-shaped PMMC, including the multiple intercostal perforators from the internal mammary vessels, may contribute to a stable blood supply of the skin island and therefore can be effective for advanced oral cancer reconstruction.

[Clinicopathological Study of the Resected Oral Leukoplakia Cases].

Oral leukoplakia is the most common premalignant or potentially malignant lesion in the oral mucosa. This retrospective study examined 67 lesions from 62 patients with clinical diagnoses of oral leukoplakia who underwent surgical excision in our department from 2015 to 2017. The patients comprised 22 men and 40 women. The most common location of the lesion was the lower gingiva, followed by the tongue, upper gingiva, buccal mucosa, palate, and lip. The most common clinical type was the white-spotted, followed by erythroleukoplakia, hillock, and verrucous types. Histopathologically, 16 lesions were oral intraepithelial neoplasia, whereas five were squamous cell carcinoma. The data identified several characteristics of oral leukoplakia that predict a high risk of malignant transformation and require aggressive surgical resection.

Oral soft tissue disorders are associated with gastroesophageal reflux disease: retrospective study.

BACKGROUND: Dental erosion (DE), one of oral hard tissue diseases, is one of the extraoesophageal symptoms defined as the Montreal Definition and Classification of gastroesophageal reflux disease (GERD). However, no study evaluated the relationship between GERD and oral soft tissues. We hypothesized that oral soft tissue disorders (OSTDs) would be related to GERD. The study aimed to investigate the association OSTDs and GERD. METHODS: GERD patients (105 cases), older and younger controls (25 cases each) were retrospectively examined for oral symptoms, salivary flow volume (Saxon test), swallowing function (repetitive saliva swallowing test [RSST]), teeth (decayed, missing, and filled [DMF] indices), and soft tissues (as evaluation of OSTDs, gingivitis; papillary, marginal, and attached [PMA] gingival indexes, simplified oral hygiene indices [OHI-S], and inflammatory oral mucosal regions). Clinical histories, which included body mass index [BMI], the existence of alcohol and tobacco use, and bruxism, were also investigated. A P value of <0.05 was defined as statistically significant. RESULTS: GERD patients, older and younger controls participated and aged 66.4 ± 13.0, 68.3 ± 8.2 and 28.7 ± 2.6 years old, respectively. The most common oral symptom in the GERD patients was oral dryness. Salivary flow volume and swallowing function in the GERD patients were significantly lower than in either of the controls (all P < 0.05). Inflammatory oral mucosal regions were found only in the GERD patients. The DMF indices, as a measure of dental caries, in the GERD patients were higher than in the younger controls (P < 0.001), but lower than in the older controls (P = 0.033). The PMA gingival indexes, as a measurement for gingival inflammation, and OHI-S, as a measure for oral hygiene, in the GERD patients were significantly higher than in either of the controls (all P < 0.05). Though no significant differences in BMI, the existence of alcohol and tobacco use were found, bruxism, as an exacerbation factor of periodontal disease, in the GERD patients was significantly more frequent than in either control group (P = 0.041). CONCLUSIONS: OSTDs were associated with GERD, which was similar to the association between DE and GERD.

[A Contrivance for Closure and Dressing of Orocutaneous Fistula Developed in Advanced Oral Cancer].

Orocutaneous fistula sometimes occurs in locallyadvanced unresectable or recurrent oral squamous cell carcinoma. The developed orocutaneous fistula results in constant leakage of saliva, ingested foods and liquids and decline in patients' quality of life(QOL). A 47-year-old Japanese man had received treatment for tongue carcinoma. At the routine follow-up, a cystic lesion in the right submandibular region was detected. Biopsyof the specimen of the cystic lesion revealed squamous cell carcinoma. After chemotherapy, an orocutaneous fistula between the right oropharyngeal and the right submandibular region developed and graduallyincreased. Although closure and dressing of the orocutaneous fistula with various materials was attempted, it was ultimatelyunsuccessful. Finally, application of a rubber film and silicone adhesive agent to the skin was successful for closure and dressing of the fistula. Orocutaneous fistula is one of major contributors to decline in patients' QOL. The sharing of information regarding effective methods or materials for closure and dressing of orocutaneous fistula is necessaryto maintain patients' QOL.

Histopathological Features of Secondary Squamous Cell Carcinoma Around a Dental Implant in the Mandible After Chemoradiotherapy: A Case Report With a Clinicopathological Review.

Oral squamous cell carcinoma (OSCC) around a dental implant is a rare pathologic condition. This report describes a case of recurrent OSCC surrounding a dental implant, histopathologic findings, and a literature review of this condition. A 58-year-old Japanese woman underwent chemoradiotherapy for OSCC in the right lower gingiva, resulting in a complete response. Nine years after primary chemoradiotherapy, a dental implant was placed in her atrophic mandible. Three years later, an OSCC developed around the dental implant in the right lower premolar region. Marginal mandibulectomy was performed. Microscopic examination showed medullary invasion around the implant surface, suggesting that tumor infiltration of the bone was through the interface between the implant and bone. However, no downward invasion through the interface was evident. OSCC can develop around dental implants that are placed for oral rehabilitation after ablative surgery. Staging of OSCC and planning of surgical management should be carried out carefully, because implants placed adjacent to the OSCC can influence tumor invasion. A high degree of vigilance for OSCC is required during follow-up of patients with dental implants who have OSCC risk factors such as premalignant lesions. Detailed evaluation, including biopsy examination, is essential for distinguishing peri-implantitis from OSCC.

Does a Retromandibular Transparotid Approach for the Open Treatment of Condylar Fractures Result in Facial Nerve Injury?

PURPOSE: The retromandibular transparotid approach (RMA) to condylar fractures of the mandible provides excellent access, but can increase the risk of complications. The aim of this study was to estimate the frequency of facial nerve paralysis (FNP) and associated postoperative complications after open reduction and rigid internal fixation (ORIF) of subcondylar fractures through the RMA. MATERIALS AND METHODS: This was a retrospective cohort study of patients with condylar fractures requiring ORIF through the RMA. The inclusion criteria were 1) a medical record of surgical treatment of a subcondylar fracture by RMA; 2) preoperative and postoperative radiographs; 3) mental status permitting an adequate neuromotor examination; 4) absence of a post-injury or pretreatment functional facial nerve deficit; and 5) regular postoperative follow-up longer than 6 months with documentation of complications, functional results, and fixation stability. The predictive variables were age, gender, fracture site, fracture pattern, concomitant fractures, etiology, and plate types. The outcome variable was FNP. Univariate, bivariate, and multiple logistic regression statistics were computed. RESULTS: Fifty patients with 55 displaced mandibular subcondylar fractures (35 men, 15 women; mean age, 44.5 yr; range, 17 to 87 yr) met the inclusion criteria. The condylar fracture involved the neck in 35 patients (63.6%) and the base in 20 patients (36.4%). The fracture pattern was deviation in 11 patients (20.0%), displacement in 23 (41.8%), and dislocation in 21 (38.2%). Precise ORIF with double-buttress fixation resulted in immediate functional recovery in all patients. Seven fractures (12.7%) were associated with FNP that resolved completely within 6 months. Further statistical analysis showed that dislocated and displaced condylar neck fractures were significant risk factors for postoperative FNP (P < .05). Other postoperative complications were minimal. CONCLUSION: The RMA for subcondylar fractures is feasible and safe. Dislocated condylar neck fractures are associated with a highly increased risk of temporary postoperative FNP as a surgical complication.

Transfection of hypoxia-inducible factor-1 decoy oligodeoxynucleotides suppresses expression of vascular endothelial growth factor in oral squamous cell carcinoma cells.

Vasculature development is thought to be an important aspect in the growth and metastasis of solid tumors. Among the many angiogenic factors produced by tumor cells, vascular endothelial growth factor (VEGF) is considered to play a key role in angiogenic processes. VEGF synthesis is modulated by hypoxia-inducible factor-1 (HIF-1) function within the hypoxic microenvironment of growing cancer tissue. To inhibit HIF-1 activation, oligodeoxynucleotides (ODNs) were synthesized and transferred with either the consensus sequence for HIF-1 binding or a mutated form of this sequence. If we could transfer a large number of ODNs into the cancer cell nucleus, activated HIF-1 might bind to the ODNs, resulting in inhibition of hypoxia-induced VEGF synthesis. We transferred these ODNs into cultured oral squamous cell carcinoma cells (SAS cells) using the hemagglutinating virus of Japan (HVJ)-liposome method. Hypoxia-mediated expression of VEGF by cancer cells was suppressed by transfection of HIF-1 decoy ODNs, but not by mutated HIF-1 decoy ODNs. HIF-1 decoy ODN transfection also inhibited VEGF protein synthesis. These results suggest that transfection with HIF-1 decoy ODNs is effective for regulating tumor growth by reducing VEGF.

Fenestration is a logical and effective treatment for a large primordial cyst with cholesterol granuloma: a case report.

A cholesterol granuloma (CG) is characterized by the presence of cholesterol crystals that cause a chronic granulomatous reaction in an enclosed space. It occurs most commonly in the head and neck region, particularly in the middle ear. Although CGs in the maxilla have also been reported, odontogenic cysts in conjunction with CGs in the maxilla are very rare. We herein present a case of a 72-year-old man who developed a large primordial cyst with a maxillary CG that extended into the maxillary sinus, nasal cavity, and infraorbital region, causing left-sided facial swelling and discomfort. We successfully controlled the symptoms and reduced the size of the lesion using the treatment approach for a common odontogenic cyst: fenestration followed by complete excision. This case suggests that fenestration is an effective technique to treat odontogenic cysts with CGs. Although the mechanisms underlying the pathogenesis and growth of CGs are still unknown, our report highlights a potential therapeutic approach for these lesions.

A Retrospective Observational Study of Risk Factors for Denosumab-Related Osteonecrosis of the Jaw in Patients with Bone Metastases from Solid Cancers.

This single-center retrospective observational study aimed to identify risk factors for developing denosumab-related osteonecrosis of the jaw (DRONJ) in stage IV solid cancer patients with bone metastases. In total, 123 consecutive patients who had received 120 mg of denosumab every 4 weeks at least twice between July 2014 and October 2018 were included. We surveyed their demographics, medical history, blood test, underlying disease, and intraoral findings. Fourteen patients (11.4%) developed DRONJ within a mean denosumab administration period of 4 months (range: 2-52 months). Univariate analyses showed a statistically significant correlation between DRONJ and hormone therapy, chemotherapy/molecular target drug, apical periodontitis, periodontal disease, sex and body mass index. Multivariate analysis showed a statistically significant correlation between DRONJ and hormone therapy (odds ratio [OR], 22.07; 95% confidence interval [CI], 2.86-170.24), chemotherapy and/or molecular targeted therapy (OR, 18.61; 95% CI, 2.54-136.27), and apical periodontitis (OR, 22.75; 95% CI, 3.20-161.73). These findings imply that collaborative oral examinations by oral specialists may reduce the risk of development of DRONJ in patients treated with denosumab for bone metastases from solid cancers.

Overview of innovative advances in bioresorbable plate systems for oral and maxillofacial surgery.

Maxillofacial osteosynthetic surgeries require stable fixation for uneventful boney healing and optimal remodeling. Although conventional titanium plates and screws for osteofixation are considered the gold standard for rigid fixation in maxillofacial surgeries, bioresorbable implants of plates and screw systems are commonly used for various maxillofacial osteosynthetic surgeries such as orthognathic surgery, maxillofacial fractures, and reconstructive surgery. Titanium plates are limited by their palpability, mutagenic effects, and interference with imaging, which may lead to the need for subsequent removal; the use of a biologically resorbable osteofixation system could potentially address these limitations. However, several problems remain including fundamental issues involving decreased mechanical strength and stability, slow biodegradation, complex procedures, and the available bioresorbable implant materials. Major advances in bioresorbable plate systems have been made with the use of bioactive/resorbable osteoconductive materials and an accelerator of bioresorption, such as polyglycolic acid. This report presents an overview of currently available resorbable implant materials and their applications, with a focus on recent innovative advances and new developments in this field.

Fracture of the Clavicle following Radical Neck Dissection and Reconstruction Using Pectoralis Major Myocutaneous Flap Accompanied by Postoperative Radiotherapy.

Fracture of the clavicle following radical neck dissection (RND) and/or radiotherapy is a rare complication. Several causes of fracture of the clavicle after treatment of head and neck cancer were postulated in previous reports. We present a case of fracture of the clavicle after treatment of squamous cell carcinoma of the tongue. An 81-year-old Japanese woman underwent RND, subtotal glossectomy, reconstruction using a pectoralis major myocutaneous flap (PMMCF), and postoperative radiotherapy (50.4 Gy). One month after the primary treatment, fracture of the clavicle occurred. It was thought that muscular dynamic factor and reduction of blood supply in the clavicle associated with RND and PMMCF were the causes of the fracture. We have to recognize the occurrence of this complication and try to reduce the factors related to the complication.

Expression of aquaporin 3 and 5 as a potential marker for distinguishing dry mouth from Sjögren's syndrome.

A study was performed to investigate whether expression of aquaporin (AQP) 3 and 5 has potential as a marker for distinguishing dry mouth from Sjögren's syndrome. Twenty-five patients underwent labial minor salivary gland biopsy (dry mouth, n = 9; Sjögren's syndrome, n = 16; control, n = 8). All patients were interviewed about their medical history and subjective oral symptoms, and intraoral examinations were conducted. Quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry were used to examine the expression and localization of AQP3 and 5. Significant differences in oral dryness, dry eye, medical history, and Saxon test results were revealed among the groups. However, there were no significant inter-group differences in expression of mRNA for AQP3 and 5. Immunohistochemical staining for AQP3 was localized mainly in the basolateral and part of the ductal cell membrane, and was barely evident in the apical membrane of acinar cells. AQP5 was localized to the basolateral and apical membrane and cytoplasm, but not the ductal cell membrane. Staining intensity for AQP3 in the apical membrane was significantly stronger in Sjögren's syndrome, and that for AQP5 was significantly weaker in dry mouth. Taken together, the present data suggest that expression of AQP3 and 5 may be a marker for distinguishing between patients with dry mouth and those with Sjögren's syndrome.

Etodolac, a selective cyclo-oxygenase-2 inhibitor, enhances carboplatin-induced apoptosis of human tongue carcinoma cells by down-regulation of FAP-1 expression.

The human tongue well-differentiated squamous carcinoma cell line, SCC-25, shows Fas-dependent apoptosis by treatment with carboplatin (CBDCA). FADD is markedly up-regulated by CBDCA, resulting in the induction of apoptosis. FAP-1, antiapoptotic tyrosine phosphatase, is expressed in the cytosol and blocks the transduction of the "death signal" from Fas to downstream. In this study, we show that etodolac, a selective cyclo-oxygenase-2 inhibitor, enhanced CBDCA-induced apoptosis of SCC-25, although etodolac alone did not induce the apoptosis. In combination with CBDCA, etodolac significantly decreased FAP-1 expression both at protein and mRNA levels, although etodolac by itself did not inhibit FAP-1 expression. These results indicate that etodolac, when combined with CBDCA, can enhance an action of anticancer drug through the suppression of FAP-1 expression.

Development or existence of non-metastatic lymph nodes in the previously operated neck: a good prognostic sign for oromaxillary squamous cell carcinoma?

The aim of this study is to clarify the clinicopathological features of patients having non-metastatic lymph nodes in the previously operated neck for oromaxillary squamous cell carcinoma (OSCC). The clinicopathological factors of 9 such patients were comparatively analyzed with those of 78 other patients who underwent neck dissection (ND). The following observations were elicited from the data: (1) These 9 patients were alive and without OSCC for periods ranging from 1 year to 15 years and 9 months since their initial cancer treatments. (2) The interval between ND and clinical and/or imaging recognition of newly developed lymph nodes with suspicion of recurrence was significantly longer in these 9 patients. (3) The initially removed lymph nodes tended to be in a less advanced stage of disease. (4) Retrospectively, discrimination of non-metastatic lymph nodes from metastatic nodes was difficult in only one patient. (5) Each of the extirpated lymph nodes from 7 of the 9 patients showed a varying grade of reactive lymphadenitis on histopathology. In conclusion, the occurrence of benign hyperplastic lymph nodes in the previously operated neck region suggested favorable prognosis, though the immunological mechanism is not understood.

A modified pectoralis major myocutaneous flap technique with improved vascular supply and an extended rotation arc for oral defects: A case report.

The pedicled pectoralis major myocutaneous (PMMC) flap is versatile, and is widely used for the treatment of surgical defects following oral cancer resection. Although free-tissue transfer of a vascularized free flap is often preferred, the clinical benefits of the PMMC flap should not be overlooked. The conventional technique of harvesting a PMMC flap involves a single vascular supply from the pectoral branch of the thoracoacromial artery. However, this approach compromises the distal skin island of the flap, and requires an indirect blood supply via communicating vessels, which increases the potential risk of partial distal flap necrosis. When harvesting a PMMC flap for oral and maxillofacial reconstruction, preservation of the lateral thoracic artery and use of the subclavian route are alternatives that ensure sufficient blood supply and an increased rotation arc. Such an approach enables the harvesting of a PMMC flap that can reach the entire oral cavity, including the infraorbital region, palate, middle pterygopalatine fossa and nasopharynx, with no risk of vascular insufficiency to the distal skin island. In conclusion, the technique described in the present study was able to improve the blood supply of the distal PMMC flap and increase its rotation arc.

Clinical Features and Treatment Modes of Mandibular Fracture at the Department of Oral and Maxillofacial Surgery, Shimane University Hospital, Japan.

BACKGROUND: The number of elderly patients with maxillofacial trauma is rapidly increasing due to active lifestyles and longevity. Shimane prefecture has the fastest growing proportion of elderly individuals in Japan. The aim of this study was to reveal the distinctive features and treatment modes of mandibular fracture treatment mode in patients requiring hospitalization at the Department of Oral and Maxillofacial Surgery, Shimane University Hospital, Japan. PATIENTS AND METHODS: Patient age, sex, period between injury and first consultation, years since injury, cause of injury, fracture site, treatment, and duration of hospitalization were evaluated. Univariate Poisson regression, relative risk with 95% confidence interval based on the Wald test, Fisher's exact test, and Kruskal-Wallis test were used to explore associations among clinical and demographic variables. RESULTS: In total, 305 patients were diagnosed with and hospitalized for mandibular fracture from 1980 to 2010. Younger age increased the risk for mandibular fracture. Incidence was higher in males than females, particularly in the young, but the male to female ratio decreased with age. The period until first hospital consultation decreased progressively over the study period. Fall was a much more frequent cause in patients aged ≥60 than in those aged <60 years. Mandibular fracture with condyle, symphysis, and angle involvement were most common and were associated with sex, age, and treatment mode. Length of hospitalization has decreased since 1980. CONCLUSION: In our department, patients aged ≥60 years accounted for a greater proportion of mandibular fracture cases than in many previous studies, reflecting the greater proportion of elderly residents in Shimane prefecture.

Nucleus Accumbens-Associated Protein 1 Expression Has Potential as a Marker for Distinguishing Oral Epithelial Dysplasia and Squamous Cell Carcinoma.

BACKGROUND: Oral epithelial dysplasia (OED) and carcinoma in situ (CIS) are defined by dysplastic cells in the epithelium. Over a third of oral squamous cell carcinoma (OSCC) patients present with associated OED. However, accurate histopathological diagnosis of such lesions is difficult. Nucleus accumbens-associated protein 1 (NAC1) is a member of the Pox virus and Zinc finger/Bric-a-brac Tramtrack Broad complex family of proteins, and is overexpressed in OSCC. This study aimed to determine whether NAC1 has the potential to be used as a marker to distinguish OED and OSCC. METHODS AND FINDINGS: The study included 114 patients (64 men, 50 women). There were 67, 10, and 37 patients with OED, CIS, and OSCC, respectively. NAC1 labeling indices (LIs) and immunoreactivity intensities (IRI) were evaluated. The patients' pathological classification was significantly associated with age, sex, NAC1 LIs, and NAC1 IRI (p = 0.025, p = 0.022, p < 0.001, and p < 0.001, respectively). As a result of multivariate analysis, a predictive model was made; this identified the NAC1 LIs (OR [95% CI] 1.18 [1.11-1.28], p < 0.001) and NAC1 IRI (0.78 [0.68-0.86], p < 0.001) as predictive factors for CIS/OSCC. The NAC1 LIs/IRI cut-off values which discriminated between OED and CIS/OSCC were 50%/124 pixels. For NAC1 LIs with > 50% positivity the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 0.766, 0.910, 0.857, and 0.847, respectively. For NAC1 IRI with ≤ 124 positive pixels, the sensitivity, specificity, PPV, and NPV were 0.787, 0.866, 0.804, and 0.853, respectively. Though there are several potential limitations to this study and the results were obtained from a retrospective analysis of a single site cohort, the data suggest that the NAC1 LIs/IRI is a strong predictor of CIS/OSCC. CONCLUSIONS: NAC1 has potential as a marker for distinguishing OED from CIS/OSCC.