Breast core needle biopsy (CNB) is an accurate test but may result in borderline histology (lesions of uncertain malignant potential or B3). This is an evaluation of the largest series (to date) of B3 histology, which focusses on estimating positive predictive values (PPV) for malignancy. We identified all B3 CNBs over a 10-year period in a single institution (N ¼ 372) from a series of 4035 consecutive needle biopsies. We describe the imaging findings, and report excision histology outcomes (N ¼ 279) and category-specific PPV for B3 lesions using two approaches including estimates based on subjects who had either excision or follow-up (N ¼ 328). B3 represented 9.2% of all CNB results. Excision histology was benign in 181 (64.9%) and malignant in 98 (35.1%) subjects (61 ductal carcinoma in situ, 37 invasive carcinoma). Positive predictive value for malignancy (based on excision histology) was 35.1% (95% CI: 29.5 -40.7) and PPV (based on excision or review) was 29.9% (95% CI: 24.9 -34.8). Lesion-specific PPV (estimates in parentheses for excision or follow-up) was atypical ductal hyperplasia 44.7% (40.6%); lobular intraepithelial neoplasia 60.9% (58.3%); papillary lesion 22.7% (15.9%); radial scar 16.7% (12.3%); phyllodes tumour 12.5% (12.5%); and B3 not specified 20.0%. Approximately one-third of CNB results classified as B3 are malignant on excision, and the likelihood of malignancy varies substantially between specific lesion groups. Whereas cases may be selectively managed without surgery, the majority warrant excision biopsy based on our estimates. Research is needed to improve differentiation between malignant and benign diseases in B3 lesions using diagnostic or predictive methods.

Breast cancer cases diagnosed in women aged 50 -69 since 1990 to 1996 in the City of Florence were partitioned into those who had been invited to screening prior to diagnosis and those who had not. All cases were followed up for vital status until 31 December 1999. The cumulative number of breast cancer deaths among the cases were divided by screening and invitation status, to give the rates of cancers proving fatal within a period of 8 years of observation (incidence-based mortality). We used the incidence-based mortality rates for two periods (1985 -86, 1990 -96), pre and during screening. The incidencebased mortality ratio comparing 1990 -96 and 1985 -86 was 0.50 (95% CI : 0.38 -0.66), a significant 50% reduction. For noninvited women, compared to 1985-86, there was a 41% significant mortality reduction (RR=0.59, 95% CI : 0.42 -0.82). The comparable reduction in those invited was a significant 55% (RR=0.45, 95% CI : 0.32 -0.61). The incidence ratio of rates of cancers stage II or worse was close to one when the noninvited in 1990 -96 were compared with 1985 -86 (RR=0.97, 95% CI : 0.78 -1.21). Excluding prevalent cases, the rate of stage II+ breast cancer cases was 42% lower in Screened women compared with the noninvited (RR=0.58, 95% CI : 0.45 -0.74). This study confirmed that new treatments and the first rounds of the screening programme contributed to reducing mortality from breast cancer.

We present a novel, international, multicenter, predictive tool to assess the risk of additional axillary metastases after tumor-positive sentinel node biopsy in breast cancer. The predictive model performed well in internal and external validation but needs to be further studied in each center before application to clinical use.