Background: Confidence in a negative stereotaxic breast biopsy result allows for safe clinical and mammographic follow-up, whereas a positive or equivocal diagnosis leads to excision. Direct comparison of stereotaxic core needle biopsy (SCBX) and fine-needle aspiration (SFNA) is needed, and should be based on the use of appropriate current methods of practice, and address the indication of each for different types of mammographic lesions.
Methods: The diagnostic accuracy of SFNA, SCBX, and combined SFNA with SCBX performed at a community radiology practice were assessed for different mammographic lesions and levels of radiologic suspicion. Negative predictive values (NPVs) measured the confidence that a negative diagnosis (failure to identify atypia or malignancy) was benign and therefore suitable for follow-up. A benign outcome was accepted only after surgical excision or > or =24 months' follow-up of the lesion. Positive predictive values (PPVs) [final diagnoses at least atypical (A) or carcinoma (CA)] also were calculated.
Results: SFNA was performed for 495 lesions and was combined with SCBX for 252 of these. Nondiagnostic (SFNA, 2%; SCBX, 8%) and atypical (SFNA, 7%; SCBX, 3%) rates were low. The authors obtained 94% follow-up (81% > or = 24 months). NPVs were all SFNAs, 99%; SCBXs, 95% (corresponding SFNAs, 98%); and SFNA with SCBX, 99%. NPVs were 100% for masses, ill-defined densities, and architectural distortions. NPVs for microcalcifications (for low, moderate, and high suspicion) were all SFNAs, 97% (100, 95, and 75); SCBXs, 93% (94, 93, and 67), corresponding SFNAs, 96% (100, 94, 75); and SFNA with SCBX, 98% (100, 97, 75). All false-negative lesions were microcalcifications. Calcium was recognized in 98% of SFNA specimens and in 89% of SCBX specimens from microcalcifications. No calcium was identified in the histologic sections in 63% (5 of 8) SCBX false-negative specimens. PPVs(A) were atypical (SFNA, 46%; SCBX, 88%) and suspicious (SFNA, 93%). PPVs(CA) were SFNA carcinoma, 100%; SCBX in situ, 89%; and SCBX invasive, 100%.
Conclusions: SFNA identified benign lesions more reliably for follow-up, particularly microcalcifications. Based on these results, the authors suggest 1) added SCBX if on-site SFNA assessment is nondiagnostic, atypical, or positive (and needs preoperative confirmation of invasion); 2) either SCBX or SFNA for masses, architectural distortions, and ill-defined densities; 3) SFNA for microcalcifications, with SCBX added for moderately and highly suspicious lesions; and 4) surgical excision for all highly suspicious microcalcifications.