The Prognostic Impact of Early Change in 18F-FDG PET SUV After Neoadjuvant Chemotherapy in Patients with Locally Advanced Breast Cancer.

UNLABELLED: SUV, which is an indicator of the degree of glucose uptake in (18)F-FDG PET, can be applied as a prognostic factor in various malignant tumors. We investigated the prognostic impact of early changes in (18)F-FDG PET uptake in patients with locally advanced breast cancer who received neoadjuvant chemotherapy.

METHODS: We retrospectively identified 87 patients who were treated with neoadjuvant chemotherapy followed by surgery for locally advanced breast cancer. All patients underwent (18)F-FDG PET at baseline and after 3 cycles of neoadjuvant chemotherapy, and the SUVmax of the primary tumor was assessed in each scan. Pathologic slides were retrospectively reviewed, and the residual cancer burden (RCB) index was calculated to estimate pathologic response. RCB-0 indicates no residual disease; patients with residual disease were categorized as RCB-1 (minimal residual disease), RCB-2 (moderate residual disease), or RCB-3 (extensive residual disease).

RESULTS: There was a negative correlation between reduction in SUVmax and RCB index (r = -0.408; P < 0.001). On multivariate analysis, ΔSUVmax was a significant independent prognostic factor for recurrence-free and overall survival, and the respective adjusted hazard ratios were 0.97 (95% confidence interval, 0.95-0.99; P = 0.001) and 0.97 (95% confidence interval, 0.95-0.99; P = 0.015). When patients were categorized into groups according to pathologic response (RCB index ≤ 1 vs. ≥ 2) and metabolic response (ΔSUVmax ≤ 66.4% vs. > 66.4%), metabolic responders had significantly better recurrence-free and overall survival than metabolic nonresponders among poor-pathologic-response patients. In contrast, among metabolic responders, there was no survival difference according to pathologic response.

CONCLUSION: The early change in (18)F-FDG PET SUVmax after third-cycle neoadjuvant chemotherapy is an independent and good prognostic marker beyond pathologic response in patients with locally advanced breast cancer. We suggest that in these patients, the use of ΔSUVmax should be considered not only for the assessment of tumor response but for the prediction of posttreatment outcome.