Purpose With the increasing uptake of Breast Screen comes an increasing number of B3 lesions that patients and surgeons must tackle. Despite existing literature demonstrating the complexities of risk prediction in this heterogenous cohort, the standard practice in many institutions is excisional biopsies of all B3 subtypes. The aim of this study is to assess the malignant upgrade rates at a tertiary centre in Western Australia (WA), in light of the recently published joint European guidelines. Methodology Records of 2,398 Breast Screen WA recalled patients who underwent core biopsies of a breast lesion from 2021 to 2023 were reviewed to identify all B3 lesions. Core versus excisional biopsy results for B3 lesions were compared to assess each subtype’s rate of upgrade to a malignant lesion. Results 125 patients had a B3 lesion. 101 had an excisional biopsy, 91 of whom had accessible final results. Within those 91 patients, upgrade rates were as follows: AIDEP 71%, papillary lesion with atypia 60%, ALH/PLCIS 50%, ADH 30.43%, fibroepithelial lesion 20%, mucocele 17%, papillary lesion without atypia 8.3%, radial scar 0% and haemangioma 0%. Conclusion Our results reflect the existing literature’s wide range of malignancy upgrade rates quoted for each B3 subtype. This can complicate counselling conversations with patients about surgery and subsequent surveillance. Options to ameliorate this clinical dilemma include using risk prediction models such the Cancer Risk Assessment Tool, or a large prospective multi-national study, to narrow the range of risk percentages quoted to patients when discussing treatment options.