Effect of previous radiotherapy on cervical lymph node fine-needle aspiration cytology diagnostic accuracy in head and neck cancers.

OBJECTIVES/HYPOTHESIS: It is not uncommon for head and neck surgeons to encounter patients with previous neck irradiation that require fine-needle aspiration cytology (FNAC) for assessment of neck mass. It had been observed that the diagnostic performance of FNAC appears to be poorer among patients with previous irradiation. However, to the best of our knowledge, the effect of previous irradiation on diagnostic performance of FNAC has never been studied.

STUDY DESIGN: Retrospective study.

METHODS: A computer search was performed to identify all patients who had been treated under the Division of Head and Neck Surgery, Department of Surgery, Queen Mary Hospital, from January 2008 to December 2010. We retrospectively retrieved all FNAC of cervical lymphadenopathy procedures, and only cases with subsequent histologic confirmation were included. All patients with squamous cell carcinoma of the head and neck (HNSCC) were included.

RESULTS: When compared to patients without previous irradiation, FNAC among patients with history of previous irradiation had comparable specificity (100% vs. 88%) and positive predictive value (100% vs. 89%) but significantly worse sensitivity (82% vs. 40%), negative predictive value (74% vs. 37%), and accuracy (88% vs. 54%). History of previous irradiation was found to be strongly associated with false-negative cytologic results among those with positive final histology (60% vs. 18%; P = .001).

CONCLUSIONS: FNAC remains an important diagnostic tool in assessment of cervical nodal status in HNSCC. However, our study showed that false-negative rate is significantly higher among patients with previous neck irradiation. Negative FNAC results in this group of patients should be interpreted with caution.