Rate of insufficient samples for fine-needle aspiration for nonpalpable breast lesions in a multicenter clinical trial: The Radiologic Diagnostic Oncology Group 5 study

BACKGROUND. Radiologic Diagnostic Oncology Group 5 is a multicenter clinical trial designed to evaluate fine-needle aspiration (FNA) of nonpalpable breast lesions performed by multiple operators using the same protocol. METHODS. Four hundred and nineteen women with mammographically detected nonpalpable breast lesions were enrolled on the trial at 18 institutions. Group A institutions randomized women to stereotactically guided FNA (SFNA) followed by stereotactically guided core needle biopsy (SCNB), or SCNB only. Group B institutions randomized women to SFNA and SCNB, SCNB, or ultrasonographically guided FNA followed by ultrasonographically guided core needle biopsy (USCNB), or USCNB only. A total of 377 women were eligible for analysis. RESULTS. FNA yielded 128 insufficient samples for the 377 patients (33.95%; 95% confidence interval, 29.2-38.7%). The rate of insufficient samples varied by type of lesion with calcified lesions associated with a significantly higher rate of insufficient sampling than masses (P < 0.001). The radiologist's level of suspicion of the lesion was not a statistically significant predictor of insufficient samples for mass lesions, but was a predictor for calcified lesions. For the 336 lesions for which histologic information was available, insufficient samples occurred in significantly more benign than malignant lesions. CONCLUSIONS. The high rate of insufficient samples for FNA of nonpalpable breast lesions in this multicenter trial makes its use impractical in this setting. Because of this factor, the study was terminated early.