Brittany Dashevsky MD, DPhil, Presenter: Nothing to Disclose

Molly Parsons MD, Abstract Co-Author: Nothing to Disclose

Maxine S. Jochelson MD, Abstract Co-Author: Nothing to Disclose

Monica Morrow MD, Abstract Co-Author: Nothing to Disclose

Gary Allan Ulaner MD, PhD, Abstract Co-Author: Research support, General Electric Company Research support, Seragon Pharmaceuticals, Inc

Studies suggest FDG PET is sensitive for lytic osseous metastases in breast cancer patients, but not blastic metastases. However, most studies have included patients who received systemic therapies, and the non-avid lesions may actually represent treated lesions. We evaluated breast cancer patients with osseous metastases at presentation, without prior systemic therapy, so the true sensitivity of FDG PET for untreated osseous metastases can be determined.

This retrospective study was performed under an IRB waiver. Our Hospital Information System was screened for breast cancer patients with osseous metastases at presentation, who underwent PET/CT prior to chemotherapy, hormonal therapy, or radiation from 2009 to 2012. Patients with invasive ductal (IDC), invasive lobular (ILC), or mixed ductal/lobular (MDL) histology were included. Patients with prior cancer history were excluded. PET/CT studies were reinterpreted by a radiologist with 9 years PET/CT experience, blinded to other imaging and biopsy results. CT appearance of osseous metastases was classified per patient as blastic, lytic, occult (seen on FDG PET only), or mixed (mix of blastic, lytic, and occult). SUVmax per patient was recorded. Medical records were reviewed for biopsy results.

95 patients met inclusion criteria (74 IDC, 13 ILC, and 8 MDL). The CT appearance and SUVmax for these patients are reported in the table. For all 74 IDC and 8 MDL patients with osseous metastases apparent on PET/CT, at least one metastasis was FDG-avid, even in patients with only blastic CT appearance. For ILC, 6 of 6 patients with mixed CT appearance, and 1 of 1 with lytic CT appearance, had at least one FDG-avid metastasis. However, only 2 of 6 ILC patients with only blastic CT appearance were demonstrable on PET.

On a per patient basis, FDG PET has high sensitivity for detection of all subgroups of untreated bone metastases in IDC, even for patients with only blastic CT appearance. Sensitivity was also high in ILC patients with mixed CT appearance. Sensitivity of FDG PET was much lower for ILC patients with blastic CT appearance. Knowledge of breast cancer histology may improve PET/CT interpretation.

On a per patient basis, FDG PET has high sensitivity for untreated osseous metastases in IDC with all CT appearances, including blastic, but not for ILC with only blastic CT appearance.

Dashevsky, B, Parsons, M, Jochelson, M, Morrow, M, Ulaner, G, Appearance of Untreated Bone Metastases from Breast Cancer on FDG PET/CT: Importance of Histologic Subtype.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14015071.html