The prognostic role of [18F]FDG PET/CT for suspected recurrence or monitoring systemic treatment in triplenegative breast cancer: preliminary results of the TRINE-PET trial.

Aim/Introduction: triple-negative breast cancer (TNBC) is an aggressive neoplasm frequently causing metastatic spread. [18F] FDG (FDG) Positron Emission Tomography (PET) is often used in daily clinical practice in case of suspect of recurrency, or for monitoring systemic treatment, although its prognostic relevance still requires further investigation. TRINE-PET is an Italian, multicenter, retrospective study, aiming to investigate the prognostic meaning of FDG PET/CT in different clinical settings of TNBC. Materials and Methods: data of TNBC patients who performed FDG PET/CT for suspected recurrency or for monitoring systemic treatment were retrospectively collected from 23 Italian centers. A minimum of 2 years of follow-up was required for inclusion. Correlation between FDG PET/CT positivity per district (T, N and M) and survival outcomes (progression and death) was evaluated with long-rank test. In patients imaged for suspected recurrency, Mann-Withney test was used to correlate the value of the onco-marker Ca-15.3 and the evidence of N+ or M+ disease at FDG PET/CT. In patients monitoring systemic treatment, the change of therapeutic management according to FDG PET/CT was collected. Results: 81 patients performing FDG PET/CT for suspected recurrency were retrieved. The median value of Ca-15.3 was 31 U/mL and lymph node and distant metastases were identified in 35 (43.2%) and 38 (46.9%) patients, respectively. After a median follow-up of 3.4 years, progression and death were reported in 45 (55.6%) and 37 (45.7%) patients. Median values of Ca-15.3 were significantly higher in patients with N+ and/or M+disease at FDG PET and dead at follow-up (38.1 vs 15.8 U/mL;p=0.01). N recurrence (p=0.018) and M recurrence (p<0.0001) at FDG PET were significantly correlated with progression at followup and M recurrence was also associated to death (p<0.0001). Data of 39 patients who performed FDG PET/CT for monitoring systemic treatment were collected, for a total of 93 studies. FDG PET/CT changed the therapeutic management in 51.2% of cases. In a per-study analysis, progression was reported in 65 (69.9%) cases and death in 43 (46.2%). A statistically significant correlation was found between the presence of N+ and M+ disease at FDG PET/CT and both progression and death at followup (both p<0.0001). Conclusion: TNBC patients with high Ca-15.3 values and evidence of N or M recurrence at FDG PET/CT have an increased risk of death. In TNBC patients with suspected recurrency or undergoing systemic therapy the evidence of N+ or M+ disease at FDG PET/CT is a strong negative prognostic factor.