E1068. Surgical Outcomes of High Risk Breast Lesions on MR-VAB
  1. Michelle Tran; Inland Imaging
Regarding high-risk lesions found on MRI-guided vacuum-assisted breast biopsies (MR-VAB), there is no general consensus regarding management, be it via surgical excision or watchful waiting. This study aims to identify factors to aid with management of these high-risk lesions (papilloma, radial scar, ADH, ALH, FEA, LCIS).

Materials and Methods:
Retrospective review of medical records and pathology results was performed on 188 patients with MR-VAB resulting in high-risk breast lesions. The 134 patients who went on to have surgical management (via excisional biopsy, lumpectomy, or mastectomy) were evaluated for tumor upgrade on surgical pathology. Various factors, such as indication, lesion size, lesion multiplicity, initial MRI indications, MRI descriptors, and MRI kinetics were noted.

Out of 134 patients with high-risk lesions and surgical pathology, 47 were upgraded to DCIS (16 out of 47) or invasive carcinoma (31 out of 47). Per lesion type, upgrade rates ranged from 28 - 67%, with the highest upgrade rates seen in LCIS (4 out of 6) and ADH (16 out of 29). Upgrade rates did not show much correlation with MRI characteristics aside from size > 1 cm (18 out of 35). Patients who underwent initial MRI to evaluate the extent of known breast cancer, then went on to have biopsy of high-risk lesions demonstrated an upgrade rate of 42% (41/97), 11 to DCIS, 30 to invasive carcinoma. Lesions found on “problem solving” MRIs had an upgrade rate of 38% (5/13), all to DCIS. Meanwhile, lesions found on high-risk screening exams only had an upgrade rate of 4% (1/24). If the highest risk lesions, ADH and LCIS, are excluded, this drops to 0% (0/22). In those with known cancer, single vs. two high-risk lesions found on MRI biopsy had upgrade rates of 40% (29/73) vs. 48% (11/23). This contrasted with the screening and problem solving group, in which single high-risk lesions upgraded at a 12% rate (4/34) and two lesions upgraded at a 50% rate (1/2). In total, there were two patients with three or more high-risk lesions, one who had known cancer and one who presented on a high-risk screening exam, with both upgrading to invasive carcinoma.

In high-risk lesions found on MR-VAB, lesion types (LCIS and ADH), size > 1 cm, known breast cancer, and multiple high-risk lesions had higher upgrade rates on surgical excision. However, prior papers on these factors have demonstrated mixed results. Lesions found on high-risk screening exams had a low upgrade rate of 4%, but this dropped to 0% upon exclusion of higher risk lesions such as LCIS and ADH. These findings suggest that in the setting of high risk screening exams, high-risk lesions found on MR-VAB may be amenable to imaging follow-up rather than surgical management, and higher power studies would be ideal in further exploring this idea.