Factors affecting the results of ultrasound-guided percutaneous biopsy in oncology

PURPOSE: Cytological or histological sampling of a neoplastic lesion, suspect or non-suspect for malignancy, either primary or metastatic, is always mandatory for indicating and planning the therapeutic work-up. Ultrasound-guided percutaneous needle biopsy is the most used technique for obtaining cellular or tissue samples, as it is quick, easy, reliable and less expensive than other techniques. The aim of this paper is to evaluate the efficacy of US-guided biopsy in responding to the clinical query with a diagnostic result, and to analyse the different factors that might influence the diagnostic adequacy of the sampled cellular or tissue material. MATERIALS AND METHODS: The results of 1897 biopsies (either cytological or histological), obtained by percutaneous US guided technique in patients with a lesion suspect for neoplasm, were evaluated in terms of adequacy or inadequacy in obtaining a pathologic diagnosis. The results were analysed with regard to the site of the lesion, the sampling method (cytological or histological) and the expertise of the operator (in terms of number of formerly executed procedures). RESULTS: The difference in adequacy of histological vs cytological sampling resulted statistically significant (94.l63% vs 71.18%, p<0.00001). The operator's former experience resulted the most important factor in determining the success of the procedure. The operators with an experience rate below 50 former procedure have, in fact, obtained inadequate material more than twice (36.29% vs 15.9%) compared to the more experienced operators: the difference was statistically significant for histological samplings. CONCLUSIONS: The period of technical learning of operators may be considered adequate after a personal experience of almost 50 procedures learning or over for microhistological sampling; while the apprenticeship is continuous and progressive for optimisation of sampling by cytoaspiration.