Integrated Positron Emission Tomography/Computed Tomography May Render Bone Scintigraphy Unnecessary to Investigate Suspected Metastatic Breast Cancer

PURPOSE: Although the accurate detection of osseous metastases in the evaluation of patients with suspected metastatic breast cancer (MBC) has significant prognostic and therapeutic implications, the ideal diagnostic approach is uncertain. In this retrospective, single-institution study, we compare the diagnostic performance of integrated positron emission tomography/computed tomography (PET/CT) and bone scintigraphy (BSc) in women with suspected MBC. PATIENTS AND METHODS: Women with suspected MBC evaluated with PET/CT and BSc (within 30 days) between January 1, 2003 and June 30, 2008, were identified through institutional databases. Electronic medical records were reviewed, and radiology reports were classified as positive/negative/equivocal for osseous metastases. A nuclear medicine radiologist (blinded to correlative and clinical end points) reviewed all equivocal PET/CT and BSc images and reclassified some reports. Final PET/CT and BSc classifications were compared. Baseline patient/tumor characteristics and bone pathology were recorded and compared to the final imaging results. RESULTS: We identified 163 women who had a median age of 52 years (range, 30 to 90 years); 32% had locally advanced breast cancer, 42% had been diagnosed with breast cancer less than 12 weeks before identification. Twenty studies were originally deemed equivocal (five with PET/CT, and 15 with BSc), and 13 (65%) of these studies were reclassified after radiology review. Overall, PET/CT and BSc were highly concordant for reporting osseous metastases with 132 paired studies (81%); 32 (20%) were positive, and 100 (61%) were negative. Thirty-one occurrences (19%) were discordant. Twelve of these (39%) had pathology confirming osseous metastases: nine (of 18) were PET/CT positive and BSc negative; one (of three) was PET/CT positive and BSc equivocal; and two (of two) were PET/CT equivocal and BSc negative. CONCLUSION: This study supports the use of PET/CT in detecting osseous metastases for suspected MBC. Whether PET/CT may supplant BSc in this setting is unknown.