Review of early stage Floor of Mouth Squamous Cell Carcinoma; The Glasgow Experience. Manjit Dhillon *, S. Doumas, A. Cooper, S. Farooq, J. McMahon, J. Devine Oral & Maxillofacial Surgery, Southern General Hospital, Glasgow, UK INTRODUCTION Significant variation exists in the clinical management of early stage floor of mouth (FOM) squamous cell carcinoma (SCC) in terms of primary treatment modality (surgery vs brachytherapy vs radiotherapy), extent of resection (periosteal stripping vs rim resection), management of N0 and contralateral neck in tumours close to or crossing the midline. Our preference is primary radical surgery where indicated for early FOM SCC with elective neck dissection when tumour depth exceeds 3-4mm. We present our experience of managing these cases. OBJECTIVES The objective of this study is to report the overall and disease-specific survival of a consecutive series of patients presenting with early FOM SCC to Southern General Hospital, Glasgow from 2008-2013 and to examine the clinical, pathological and therapeutic factors relating to these cases. RESULTS 57 cases of FOM SCC were identified Elective Neck Dissection METHODS Patients were identified from the departmental Head & Neck cancer database. Data was collected retrospectively using electronic patient records. 57 consecutive cases of clinically & radiologically T1-T2, N0 SCC were identified from the cancer database between 2008-2013. All patients were previously untreated, and underwent primary curative surgery. Exclusion Criteria •Non-SCC pathology •Recurrent disease •Synchronous tumours •Cases with incomplete data •Patients unfit for surgery Raw data was analyzed using Excel, SPSS & Medcalc. References 1. Fu KK, Lichter A, Galante M. Carcinoma of the floor of mouth: an analysis of treatment results and the sites and causes of failures. Int Radiat Oncol Biol Phys. 1976 Sep-Oct;1(9-10):829-37. 2. Aygun C, Salazar OM, Sewchand W, Amornmarn R, Prempree T. Carcinoma of the floor of the mouth: a 20-year experience. Int Radiat Oncol Biol Phys 1984 May;10(5):619-26. 3. Dias F et al Cancer of the floor of mouth. Operative Techniques in Otolaryngology, Vol 16, No 1, March 2005 4. Sessions DG, Spector GJ, Lenox J, Parriott S, Haughey B, Chao C, Marks J, Perez C. Analysis of treatment results for floor-of-mouth cancer. Laryngoscope 2000 Oct;110(10 Pt 1):1764-72. 5. Hicks WL, Loree TR, Garcia RI, Maamoun S, Marshall D, et al. Squamous cell carcinoma of the floor of mouth: a 20-year review. Head Neck 1997 Aug;19(5):400-5. 6. Pimenta Amaral TM, Da Silva Frejre AR et al Predictive factors of occult metastasis and prognosis of clinical stages I and II squamous cell carcinoma of the tongue and floor of the mouth. Oral Oncology 2004 Sep;40(8):780-6. 63% 37% Male/Female Male Female 79% 21% pT Stage pT1 N0 pT2 N0 Tumour Size & Depth Range Average Tumour size 0.7-29mm 12.9mm Tumour depth 0.4-15mm 4.6mm Margin Status n=57 >5mm 46 (81%) 1-5mm 9 (16%) <1mm 2 (3%) Perineural /Lymphovascular Invasion n=57 Perineural Invasion 10 (18%) Lymphovascular invasion 8 (14%) Both 4 (7%) 46% 54% Marginal Mandibulectomy Performed None 56 cases Elective Neck Dissection N=38 (68%) pN+ N=9 (24%) PORT N=8 (89%) OS= 63% No PORT N=1 (11%) OS=100% pN- N=29 (76%) OS=93% No Neck Dissection N=18 (32%) No PORT N=17 (94%) OS=94% PORT N=1 (6%) OS=0% Rim Resection Tumours within 1cm of the resection margin underwent marginal mandibulectomy (46%) to ensure an oncologically safe margin. No patients underwent periosteal stripping. Histopathologically, no cases revealed frank bony invasion, and 1 case demonstrated cortical erosion only. *Contact Manjit Dhillon email: m.dhillon@nhs.net Conflicts of interest: None Ethical approval obtained: None required CONCLUSION Although this is a small series of patients, it represents a homogeneous sample of early FOM SCC. Although bony involvement was not evident in any of the resections, it permits a confident safe margin around tumours close to the mandible and reflects in our high marginal clearance rates. Our survival rates also compare very favourably against other published series in early stage floor of mouth SCC. Data on neck management was available for 56 cases. 13.5% of pT1 & 25% of pT2 were upstaged to Stage 3 or 4 due to pN+. Average follow-up time was 37.4 months. For Stage 1 & Stage 2 disease Kaplan Meier Survival curves revealed the disease specific survival to be 97.5% & 77.8% and overall survival 92.5% & 77.8% respectively.