Prognostic value of tumor heterogeneity from initial FDG PET/CT in patients with locally advanced breast cancer

Objectives To evaluate the prognostic value of tumor heterogeneity from initial FDG PET/CT in patients with locally advanced breast cancer.

Methods FDG PET/CT images from January 2007 to June 2012, performed for initial staging of breast cancer in 54 female patients (mean age 47±9 years) undergoing neoadjuvant chemotherapy followed by curative surgery were retrospectively reviewed. Heterogeneity of the primary tumor was assessed visually and categorized into 3 groups: homogeneous, equivocal, and heterogeneous. Quantitative analysis was performed by computing standard deviation of standardized uptake value (SD_SUV). In addition, parameters including metabolic tumor volume (MTV) using threshold SUV of 2.5, total lesion glycolysis (TLG), mean and maximum SUV were measured from the primary tumor. Median values of each parameter were used to dichotomize the patients. The disease free survival (DFS) was calculated by Kaplan-Meier method.

Results The mean follow-up was 33.4±14.6 months (range 3.7-76.7 mo). Recurrence was identified after curative surgery in 11 patients. With visual assessment of tumor heterogeneity, there were 22 homogeneous, 12 equivocal and 20 heterogeneous cases. On univariate analysis, tumor heterogeneity showed statistically significant correlation with DFS (p=0.046). Patients with homogeneous tumors (DFS 38.8±15.0 mo) showed longer DFS compared to the patients with heterogeneous (25.8±12.8 months, p=0.028) tumors. SD_SUV, MTV, TLG, SUV_mean and SUV_max showed no significant prognostic value for DFS.

Conclusions Tumor heterogeneity assessed visually from initial FDG PET/CT provided prognostic information in patients with locally advanced breast cancer. Patients with homogeneous tumor showed longer DFS compared to patients with heterogeneous tumors.