PET Scan in Head and Neck Tumours in a Developing Country Like India: Is It a Must?

Abstract

To study the impact of Positron emission tomography (PET) and its incremental value in diagnosing an unknown primary tumour with secondaries in the head and neck; recurrent head and neck cancers (confirmation of suspected recurrences and re-staging); and staging of head and neck tumours. This was a prospective observational study where 60 patients of head and neck tumours under the clinical settings as described above were evaluated. Thorough clinical examination and necessary radiological and histopathological investigations were done. All patients underwent a PET scan, the results of which were correlated with histopathological examination. Sensitivities, specificities, positive and negative predictive values, false positives and false negatives of PET scan in the different indications were calculated. The study included 11 patients of unknown primary, 28 patients with suspected recurrent tumours and 21 patients where PET scan was done for initial staging. PETCT scan was able to detect the primary in 3 out of 11 patients (27.27%) who presented with cervical metastases with an unknown primary. In 2 of the 8 patients where a primary tumour was not found, PETCT detected distant metastases. For recurrent tumours, PETCT scan showed sensitivity, specificity, positive predictive value and negative predictive value as 100, 72.72, 85 and 100% respectively. In restaging of recurrent disease, 4 out of 28 patients were detected to have distant metastases. In 7 cases of locoregionally advanced tumors, where PETCT scan was used for pre-treatment staging, it detected distant metastases in 4 of 7 patients. In the patients with N0 neck status PETCT scan showed a sensitivity, specificity, positive predictive value and negative predictive value of 100, 66.67, 50 and 100% respectively. PETCT scan was able to alter the plan of management in 15 out of 60 patients. Thus, in carefully selected patients PETCT scan can provide incremental information that proves invaluable in these circumstances even in a developing country like India. In all the settings, PETCT scan demonstrated a very high negative predictive value. Hence, negative PETCT scan could be interpreted as absence of disease with reasonable assurance.