RATIONALE AND OBJECTIVES

To determine the diagnostic accuracy of stereotactically and sonographically guided core biopsy (CB) for the diagnosis of nonpalpable breast lesions.

MATERIALS AND METHODS

Twenty-two institutions enrolled 2,403 women who underwent imaging-guided fine needle aspiration followed by imaging-guided large-CB of nonpalpable breast abnormalities. All mammograms were reviewed for study eligibility by one of two breast imaging radiologists. The protocol for image-guided biopsy, using either ultrasound (USCB) or stereotactic (SCB) guidance, was standardized at all institutions and all biopsy specimens were over-read by one of three expert pathologists. Patients with atypical ductal hyperplasia (ADH), atypical lobular hyperplasia, or lobular neoplasia on CB underwent surgical excision. Those with negative CB but suspicious ("discordant") pre-biopsy mammography also underwent surgical excision. Patients having a negative CB that was concordant with the pre-biopsy mammography suspicion were assigned to follow-up mammography at 6, 12, and 24 months following CB.

RESULTS

A gold standard diagnosis based on definitive histopathologic diagnosis, mammography follow-up, or an imputed gold standard diagnosis was established for 1,681 patients. Of 310 cases with a gold standard diagnosis of invasive breast carcinoma, 261 (84.2%) were invasive carcinoma, 31 (10%) were ductal carcinoma in situ (DCIS), four (1.3%) were ADH, one (0.3%) was a non-breast cancer, and 13 (4.2%) were benign on CB. For 138 cases with a gold standard diagnosis of DCIS, 113 (81.9%) were DCIS, 20 (14.5%) were ADH, and five (3.6%) were benign on CB. For 57 cases (13 masses, 44 calcifications) with an initial CB diagnosis of ADH, atypical lobular hyperplasia or lobular neoplasia, 20 (35.1%) had a gold standard diagnosis of DCIS (4 masses, 16 calcifications) and four (7.0%) had a gold standard diagnosis of invasive cancer (4 calcifications). Of 144 cases (22 masses, 122 calcifications) with an initial CB diagnosis of DCIS, 31 (21.5%) had a gold standard diagnosis of invasive cancer (10 masses, 21 calcifications). The sensitivity, specificity and accuracy for CB by either imaging guidance method in this trial were .91, 1.00, and .98, respectively. The sensitivity, predictive value negative, and accuracy of CB for diagnosing masses (.96, .99, and .99, respectively) were significantly greater (P < .001) than for calcifications (.84, .94, and .96, respectively). The sensitivity (.89) of SCB for diagnosing all lesions was significantly lower (P = 0.029) than that of USCB (.97) because of the preponderance of calcifications biopsied by SCB versus USCB. There was no difference between USCB and SCB in sensitivity, predictive value negative, or accuracy for the diagnosis of masses (97.3, 98.9, and 99.2, respectively for USCB; 95.6, 98.5, and 98.9 respectively for SCB).

CONCLUSION

Percutaneous, imaged-guided core breast biopsy is an accurate diagnostic alternative to surgical biopsy in women with mammographically detected suspicious breast lesions.