Pilot study: prognostic significance of semi-quantitative parameters in baseline fluorine‑18 fluorodeoxyglucose PET/computed tomography in nonmetastatic breast cancer patients

BACKGROUND: Breast cancer demonstrates heterogeneous clinical behavior, underscoring the need for reliable prognostic biomarkers. Semi-quantitative parameters derived from fluorine‑18 fluorodeoxyglucose PET/CT, including spleen maximum standardized uptake value (SUVmax) and spleen-to-liver SUVmax ratio (SLR), may reflect systemic inflammatory activity and predict outcomes. OBJECTIVE: To assess the prognostic significance of baseline spleen SUVmax and SLR, compared with other PET/computed tomography (CT)-derived parameters, in predicting disease-free survival (DFS) in nonmetastatic breast cancer. METHODS: Ninety-two female patients with pathologically confirmed invasive breast cancer underwent baseline fluorine‑18 fluorodeoxyglucose PET/CT before treatment. SUVmax values for primary tumor, spleen, and bone marrow were measured, and SLR and bone marrow-to-liver SUVmax ratios were calculated. Associations with clinicopathological features were analyzed using chi-square and ANOVA tests. DFS predictors were evaluated using Cox regression and Kaplan-Meier analysis. RESULTS: Higher spleen SUVmax and SLR were significantly associated with larger tumor size, advanced stage, higher grade, hormone receptor negativity, and triple-negative subtype (P < 0.05). Patients with progressive disease had higher spleen SUVmax (2.93 ± 0.50) and SLR (0.87 ± 0.06) than those with complete remission (P < 0.001). In univariate Cox regression, SLR remained a strong predictor of DFS [hazard ratio = 6.12, 95% confidence interval (CI): 2.05-18.25, P = 0.001]. In multivariate analysis including SLR, Ki-67, stage, nodal status, and molecular subtype, only SLR remained independently significant (hazard ratio = 6.12, 95% CI: 2.05-18.25, P = 0.001). Patients with SLR greater than 0.7083 had significantly shorter mean survival (14.5 vs. 31.6 months, P < 0.001). CONCLUSION: Baseline SLR is a strong prognostic marker in nonmetastatic breast cancer along with tumor SUVmax and spleen SUVmax, and may aid in risk stratification and treatment planning.