Is [18F] fluorodeoxyglucose uptake by the primary tumor a prognostic factor in breast cancer?

Background: We retrospectively investigated ¹⁸F-FDG uptake by the primary breast tumor as a predictor for relapse and survival. Patients and methods: We studied 203 patients with cT1-T3N0 breast cancer. Standardized uptake value (SUVmax), was measured on the primary tumor. After a median follow-up of 68 months (range 22-80), the relation between SUVmax and tumor factors, disease free-survival (DFS) and overall survival (OS) was investigated. Results: In the PET-positive patients, the median FDG uptake by the tumor was 4.7. FDG uptake was significantly related to tumor size, number of involved axillary nodes, grade, negative ER, high Ki-67 and HER2 overexpression. No distant metastases or deaths occurred in the PET-negative group. Five-year DFS was 97% and 83%, respectively in the PET-negative and PET-positive groups (P = 0.096). At univariate analysis, DFS was significantly lower in patients with SUVmax >4.7 compared to the patients with negative PET (P = 0.042), but not to the patients with SUVmax ≤4.7 (P = 0.106). At multivariable analysis, among PET-positive patients, SUVmax was not an independent prognostic factor for DFS (HR_{>4.7 vs ≤4.7}: 1.02 (95% CI 0.45-2.31)). Five-year OS was 100% and 93%, respectively, in the PET-negative and PET-positive groups (P = 0.126). Conclusion: FDG uptake by the primary lesion was significantly associated with several prognostic variables, but it was not an independent prognostic factor.