Clinical study of keratocystic odontogenic tumors

The odontogenic keratocyst (OKC) was originally classified as a developmental cyst, and OKCs were histologically divided into orthokeratotic (O-OKCs) and parakeratotic (P-OKCs) types. Clinical features differ between O-OKCs and P-OKCs with P-OKCs having a tendency to recur after surgical treatment. According to the revised histopathological classification of odontogenic tumors by the World Health Organization (2005) , the term keratocystic odontogenic tumor (KCOT) has been adopted to describe P-OKCs. In this retrospective study, we examined 186 KCOTs treated at the Maxillofacial Surgery Department of the Tokyo Medical and Dental University Hospital from 1981 through 2005. The patients ranged in age from 7 to 85 years (mean, 32.7) and consisted of 93 males and 93 females. The most frequently treated areas were the mandibular molar region and ramus. The majority of KCOTs in the maxillary region were treated by enucleation and primary closure. The majority of KCOTs in the mandibular region were enucleated, and the wound was left open. Marginal resection was performed in the 4 patients with large lesions arising in the mandible. In patients who were followed for more than a year, recurrences were observed in 19 of 120 lesions (15.8%) . The recurrences were found at the margins of the primary lesion in contact with the roots of the teeth or at the upper margins of the mandibular ramus. Clinicians should consider aggressive treatment for KCOTs because the recurrence rate of P-OKCs is higher than that of other cyst types such as O-OKCs, dentigerous cysts, primordial cysts that were non-keratinized, and slightly keratinized stratified squamous epithelium. Although more aggressive treatment is needed for KCOTs as compared to other cystic lesions, it is difficult to make a precise diagnosis preoperatively on the basis of clinical features and X-ray imaging. Therefore, preoperative biopsy is necessary for selecting the appropriate treatment for patients with cystic lesions.

Simultaneous Assessment of Cyclin D1 and Epidermal Growth Factor Receptor Gene Copy Number for Prognostic Factor in Oral Squamous Cell Carcinomas / Oral Science International

Cyclin D1 gene (<i>CCND1</i>) numerical aberrations are independent prognostic indicators of head and neck squamous cell carcinomas (HNSCCs). High epidermal growth factor receptor gene (<i>EGFR</i>) copy number is associated with poor prognosis in lung cancer, but such findings are controversial in oral SCCs (OSCCs). We analyzed copy number status in <i>CCND1</i> and <i>EGFR</i> in OSCC patients and its association with clinical outcome.<i>EGFR</i> and <i>CCND1</i> statuses were analyzed in 85 OSCC patients by fluorescence <i>in situ</i> hybridization (FISH) of specimens obtained by fine-needle aspiration biopsy.<i>CCND1</i> numerical aberration was found in 35 of 85 tumors (41%), and aberrant <i>EGFR</i> copy number was observed in 36 (42%). Gene amplification (GA) was dominant among <i>CCND1</i> copy number changes (14/35:40%). Balanced trisomy (BT) was the most frequently observed <i>EGFR</i> aberration (17/36:47%). In a multivariate Cox's proportional hazards analysis, <i>CCND1</i> GA was correlated with disease-free survival (<i>P</i><0.001), whereas <i>EGFR</i> BT was significantly correlated with overall survival (<i>P</i>=0.001). Patients with a combination of <i>CCND1</i> GA and/or <i>EGFR</i> BT had significantly poorer clinical outcome.<i>CCND1</i> and <i>EGFR</i> copy number changes were frequent in OSCC and had differing aberration patterns. <i>CCND1</i> GA and <i>EGFR</i> BT statuses by dual-color FISH were the predominant predictors of clinical outcome. Further investigation is needed to determine the implications for EGFR inhibitor therapy in OSCC.