Purpose: 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.
Procedures: 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.
Results: 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).
Conclusions: 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.