To Assess the Clinical Impact of 18F-FDG PET/CT in Non-Treated Cases of Squamous Cell Carcinoma of Head and Neck Presenting with Clinically and/or Radiologically N0 Status

Background: The most common sites are the oral cavity, pharynx and larynx and 85% to 95% neoplasms of the head and neck are SCCHN. The preservation of function, especially as it relates to speech, swallowing, and mastication, as well as cosmetic considerations, are considered essentials for determining the most effective management paradigm for SCCHN. The most common known imaging modalities in clinical use are CT and MRI imaging, despite their suboptimal sensitivity and specificity for the detection of distant metastases. The aim of present study is to establish the impact of 18F-FDG PET/CT in clinically and/or radiologically negative neck in the assessment of cervical lymph nodes. Materials & Methods: The present study was conducted in the Department of Nuclear Medicine and PET CT, Sudhamayi Hospitals and Clinics, Cochin, Kerala over a period of about one and half years. The study group comprised of untreated patients of both sexes with age ranging from 20 to 81 years referred to our department with an established tissue diagnosis of SCCHN for 18F-FDG-PET/CT Whole Body scan for evaluation of disease status and staging. 8 -10 mCi of 18F-Flouro-Deoxy-Glucose (18F-FDG) was injected I.V. in euglycemic status. Time of injection was noted along with pre-injection and post injection counts. Whole body PET/CT images (head to mid-thigh) were acquired after 45 min to 60 min post injection. Data including age, sex, endoscopy (direct / indirect) findings, neck lymph nodes level by clinical examination and radiological finding, FNAC/histopathology report of the primary and /or lymph nodes and conventional imaging (CT/MRI when available) findings was recorded. SPSS software was used for analysis. Results: At presentation, in 32.4% (n-12) of patients no nodes were palpable. Ipsilateral (single / multiple levels) lymph nodes were present in 48.7% of the patients (n-18). Bilateral involvement was seen in 18.9% (n-7) of the cases. Patient with FDG non avid necrotic lymph node was staged N0 on PET/CT but clinically had N2c disease was excluded from further analysis. There was no change in the overall stage or management of this patient. Conclusion: 18F-FDG PET/CT can accurately predict N stage better than clinical / conventional imaging leading to change in nodal staging and thus overall staging of patients. Thus it acts as a valuable tool in determining the exact nodal spread of squamous cell carcinoma and thus establishing the exact treatment plan.