Degree of Tumor FDG Uptake Correlates with Proliferation Index in Triple Negative Breast Cancer

2-Deoxy-2-[F-18]fluoro-D-glucose (FDG) uptake may be a useful surrogate marker for proliferation index, but the correlation has not always been clear-cut. Previous research by our group suggests that FDG-positron emission tomography (PET) is sensitive in detecting triple negative breast cancer. We therefore performed a pilot study to test if FDG uptake correlated with proliferation index in women with triple negative cancer. To determine whether proliferation index correlates with metabolic uptake of FDG in women with triple negative breast cancer, we performed a retrospective analysis correlating %Ki67 nuclear stain with tumor maximum standardized uptake values (SUVmax) in a group of 41 women, 22 with triple negative and 19 with non-triple negative breast cancer. As expected, [18F]-PET imaging was significantly more sensitive in detecting triple negative breast cancer than non-triple negative breast cancer, 95.5% vs 68.4% (p = 0.036). In general, SUVmax and %Ki67 nuclear stain values rise as histologic grade worsens. Histologic grade of triple negative breast cancer was more often poorly differentiated than non-triple negative cancer (p = 0.001). SUVmax correlated with %Ki67 nuclear staining in our entire cohort (spearman correlation = 0.485, p = 0.002). Moreover, this significant correlation appeared to be driven primarily by a subset of women with triple negative cancer (spearman correlation = 0.497, p = 0.019). Degree of tumor FDG uptake correlated significantly with proliferation index in women with triple negative breast cancer suggesting a potential role of FDG-PET in treatment response monitoring for this group of women. Future studies are necessary to define the role of PET imaging as a non-invasive means to monitor breast cancer treatment response in the neoadjuvant setting.