The performance of fine needle aspiration cytology (FNAC) compared to histology in the preoperative diagnosis of thyroid cancer: a single centre study

Abstract

Background: Thyroid cancer is the most common endocrine malignancy globally. Fine needle aspiration cytology (FNAC) is used in the diagnostic workup of thyroid nodules. There have been discrepancies between FNAC and histology at Charlotte Maxeke Johannesburg Academic Hospital (CMJAH). This prompted a study to determine the performance of FNAC compared to histology in diagnosing thyroid cancer at CMJAH.

Methods: A retrospective review of patients who underwent thyroid surgery at CMJAH between 1 January 2015 and 1 September 2022 was conducted. Patient details were accessed via the theatre registry and the department of nuclear medicine. FNAC and histology results were accessed using the National Health Laboratory Service (NHLS) website. The data was collected and entered into a Microsoft Excel spreadsheet. STATA statistical software was used to analyse the data.

Results: A total of 369 patients were screened, of which 222 were included in the study. We found the prevalence of thyroid cancer at CMJAH to be 35.6%. FNAC was found to have a sensitivity of 83.6% and a specificity of 88.7%. Its accuracy was 0.861 and it had a PPV of 81.2% and a NPV of 90.3%. The likelihood ratio generated was 7.39. PTC was found to be the most prevalent subtype with the FNAC malignancy detection rate of 85%.

Conclusion: Our study showed that FNAC performed well in diagnosing thyroid cancer preoperatively. Therefore, it should continue to be used in the diagnostic workup of thyroid nodules at CMJAH.