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Nuclear Medicine

E3139. Male Breast Cancer: Molecular Profile and Impact of F18 FDG PET/CT on Its Staging and Management

Waxman J,  Garg I,  Goenka A. Mayo Clinic, Rochester, United States

Address correspondence to J. Waxman (waxman.jacob@mayo.edu)

Objective: Male breast cancer is an aggressive neoplasm that is often diagnosed at advanced stages. Accurate staging and assessment of disease recurrence or progression are critical for management. The purpose of our study was to evaluate the molecular profile of male breast cancer patients undergoing F18 FDG PET/CT and to evaluate the accuracy of PET/CT in staging and its impact on management.

Materials and Methods: In this institutional review board–approved, HIPAA-compliant retrospective study, our institutional PET/CT database (July 2006 to September 2016) with more than 12,000 patients was searched for male patients with breast cancer. We identified 39 PET/CT scans in 19 male breast cancer patients (mean age, 63 years; range, 40–82 years) for initial staging (n = 19) and restaging and/or follow-up (n = 20). Three scans (two for initial staging, one for restaging) were excluded due to insufficient follow-up. Tumor profile and clinical management were noted from electronic medical records. A dual board-certified radiologist blinded to results of PET/CT re-reviewed each study for reverification of findings noted on the original PET/CT report. Accuracy of PET/CT for initial staging and restaging and its impact on management was assessed based on a composite reference standard consisting of biopsy results, further work-up, and follow-up. Change in management was defined as either an alteration in treatment regimen, upstaging of disease from prior conventional imaging, or averting a preplanned invasive procedure or treatment.

Results: Mean time to follow-up (clinical follow-up or death) was 5.9 years (range, 1–20 years). Histology was invasive ductal carcinoma (n = 16), ductal carcinoma in situ (n = 1), non–small cell adenocarcinoma (n = 1), and unknown (n = 1). All tumors were unilateral and unifocal. Molecular profile was estrogen receptor positive (19/19), progesterone receptor positive (17/18), HER2 positive (3/14), high Ki-67 index (4/7), and BRCA2 gene positive (1/11). Molecular subtype of tumors was either luminal A (57%; 8/14) or luminal B (43%; 6/14) with no HER2 type or triple negative type tumor. A majority of patients had grade 2 or higher (88.2%; 15/17) and stage 2 or greater disease (64.7%; 11/17) at initial staging. At initial surgical staging, 12 patients had axillary nodal metastases. PET/CT demonstrated additional axillary (n = 2) and distant (n = 3) nodal metastases in five patients and distant metastases in six patients that included lungs (n = 6), bones (n = 5), and soft tissue (n = 1). Based on composite reference standard, PET/CT was 100% accurate in staging or restaging MBC. PET/CT led to a change in management of both initial staging (10/17) and restaging or follow-up (8/19).

Conclusion: A majority of male breast cancer tumors were estrogen receptor/progesterone receptor positive. Yet, PET/CT demonstrated excellent accuracy in initial staging or restaging and led to a change in management in a majority of patients.