O-49 The Positive (biopsy proven) Predictive Value of the Breast Imaging Reporting and Data System Category 3, 4 and 5 at the University Hospital of The West Indies

Methods: Mammography reports of patients with prior ultrasound guided core needle biopsy were retrospectively reviewed from the data archiving system and those assigned BI-RADS categories 3-5 during the three-year study period were analysed. The histology reports were matched to BI-RADS categories assigned and the positive predictive values of the categories were determined after exclusion criteria was applied.

Results: There were 268 suitable cases of which 140 are benign and 128 malignant. Fibroadenoma is the most prevalent benign histology and invasive ductal carcinoma is the most prevalent malignant subtype. The average age for benign and malignant lesions is 43 and 51, respectively. Specifically for malignant lesions, upper-outer quadrant (57%) is most commonly involved and 45% axillary involvement was demonstrated. The commonly observed imaging features for BI-RADS 4 and 5 lesions is ill-defined mass on mammogram and hypoechoic ill-defined mass on ultrasound. The PPV for malignancy of BI-RADS categories was 8% for BI-RADS 3, 69% for BI-RADS 4 and 98% for BI-RADS 5.

Conclusion: The positive predictive value for the BI-RADS categories examined in this study corresponds to the literature for categories 4 (study 69% vs literature 2-95%) and 5 (study 98% vs literature >= 95%). For BI-RADS 3 category, we demonstrated an 8% PPV compared to the literature 0-2%. The Jamaican population is predominately black, which increases the risk for malignancy despite less aggressive features on imaging. Therefore, we recommend biopsy for higher-risk patients, even if benign features are demonstrated on imaging.