Impact of FDG PET on defining the extent of disease and on the treatment of patients with recurrent or metastatic breast cancer.

OBJECTIVE Our aim was to evaluate the impact of FDG PET on defining the extent of disease and on the treatment of patients with advanced breast cancer. MATERIALS AND METHODS The medical records of 125 consecutive patients with recurrent or metastatic breast cancer referred for FDG PET from January 1998 through May 2002 were retrospectively reviewed. The rationale for FDG PET referral and the impact of FDG PET on subsequent treatment decisions for patients were determined by chart review. The impact of FDG PET on defining the extent of disease was determined by comparing the FDG PET interpretation at the time of the examination with findings from conventional imaging (CI) performed before FDG PET. FDG PET results were confirmed in nearly half (n = 61) of the patients by histopathology (n = 23) or follow-up imaging (n = 38; mean follow-up interval, 21.3 months). RESULTS Patients were referred for FDG PET for the following reasons: evaluation of disease response or viability after therapy (n = 43 [35%]), local recurrence, with intent of aggressive local treatment (n = 39 [31%]), equivocal findings on CI (n = 25 [20%]), evaluation of disease extent in patients with known metastases (n = 13 [10%]), and elevated tumor markers with unknown disease site (n = 5 [4%]). Compared with CI findings, the extent of disease increased in 54 (43%), did not change in 41 (33%), and decreased in 30 (24%) of 125 patients using FDG PET. Results of FDG PET altered the therapeutic plan in 40 (32%), directly helped to support the therapeutic plan in 34 (27%), and did not change the plan devised before FDG PET in 51 (41%) of 125 patients. FDG PET altered therapy most frequently in the patients suspected of having locoregional recurrence and in those being evaluated for treatment response versus other referral categories (p = 0.04). For patients with confirmation of FDG PET findings, the sensitivity, specificity, and accuracy of FDG PET were 94%, 91%, and 92%, respectively. CONCLUSION FDG PET contributes significantly to defining the extent of disease and deciding on treatment of patients with advanced breast cancer.