Examining the sensitivity of ultrasound-guided large core biopsy for invasive breast carcinoma in a population screening programme.

Introduction: To evaluate the sensitivity of ultrasound-guided core-needle biopsy (UCB) in invasive breast carcinoma and to establish causes of false-negative biopsy in a population screening programme.

Method: We identified 571 consecutive women diagnosed with surgically proven invasive breast cancer. Histology from 14-gauge UCB was compared with surgical histology to identify true-positive and false-negative ultrasound core biopsies. True-positive and false-negative groups were compared for tumour size and histology. On blinded review of UCB images and pathology reports from false negative (n = 20) and a random sample of true-positive cases (n = 80), we compared core sample number and needle visualisation in the lesion.

Results: Of 571 carcinomas sampled with UCB, 551 (96.5%) were true positive and 20 (3.5%) were false negative. The mean core number was 2.0 (range 1-3) for false negatives and 2.25 (range 1-4) for true positives (P = 0.27). Mean tumour sizes were 13.3 and 16.2 mm for the false-negative and true-positive groups, respectively (P = 0.25). Tubular carcinomas represented 30% (6/20) of false-negative cases compared with 5.1% (28/551) of the true-positive cases (P < 0.001). On blinded review, needle visualisation within the lesion was demonstrated in 47.4% (9/19) of false-negative cases and 76.3% (61/80) of true-positive cases (P = 0.02).

Conclusion: We demonstrated a sensitivity of 96.5% with a mean of 2.21 cores. False-negative results were more likely in the absence of post-fire needle position verification and with tubular carcinomas. Neither tumour size nor core number predicted diagnostic accuracy.