RT Journal Article SR Electronic T1 18F-FDG PET for Staging Breast Cancer in Patients with Inner-Quadrant Versus Outer-Quadrant Tumors: Comparison with Long-Term Clinical Outcome JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1455 OP 1459 VO 46 IS 9 A1 Amy Tran A1 Betty S. Pio A1 Bahareh Khatibi A1 Johannes Czernin A1 Michael E. Phelps A1 Daniel H.S. Silverman YR 2005 UL http://jnm.snmjournals.org/content/46/9/1455.abstract AB Extraaxillary metastases (i.e., in the absence of axillary involvement) are more likely to develop in patients with inner-quadrant (IQ) breast cancer than in patients with outer-quadrant (OQ) primary tumors. The relative difficulty of identifying extraaxillary metastases may lead to understaging of cancer in these patients. This study examined whether 18F-FDG PET findings were differentially associated with the location of primary tumors, and with long-term prognosis, in IQ and OQ patients. Methods: Follow-up data were obtained for 141 patients whose breast cancer was staged by PET and who were documented to have IQ (n = 42) or OQ (n = 99) primaries. Results were stratified according to PET findings consistent with different metastatic patterns. Data were further analyzed with respect to disease outcome after a mean 3-y follow-up period. Results: Among IQ patients, progressive disease was identified in 26.1%, compared with 13.1% of OQ patients, for a relative risk (RR) of 2.0. Of patients with PET findings of isolated extraaxillary metastases, 36.1% had progressive disease, compared with 10.7% of other patients (RR = 3.4), and 61.9% of IQ patients had isolated extraaxillary metastases identified on PET, compared with 10.1% of OQ patients (RR = 6.1). Conclusion: IQ patients demonstrated a 6-fold greater frequency of PET findings of isolated extraaxillary metastasis, and such findings were associated with triple the risk for disease progression. Patients with IQ tumors could be vulnerable to understaging with conventional staging approaches and may particularly benefit from PET during the staging process.