Diagnostic and prognostic impact of fluorine-18-fluorodeoxyglucose PET/CT in preoperative and postoperative setting of breast cancer patients.

Purpose: The aim of this study was to assess the diagnostic and prognostic value of fluorine-18-fluorodeoxyglucose (F-FDG) PET/CT in patients with breast cancer (BC) in the preoperative and the postoperative setting.
Patients and Methods: Between 2011 and 2015, we prospectively enrolled 275 patients (mean age: 53 years) with BC (stage I-III; triple-negative or HER2-positive cancer). One-hundred and forty-nine (54.2%) patients underwent F-FDG PET/CT before neoadjuvant therapy and 126 (45.8%) after surgery and before any additional adjuvant therapy. The patients were followed for a median period of 44 (2-57) months. The different effects of PET/CT on the presetting and postsetting phase form a therapeutic and prognostic point of view were assessed by χ, by Kaplan-Meier, and Cox-regression analyses.
Results: In the preoperative setting, PET/CT provided additional diagnostic information in 42/149 (28%) patients. In particular, 17/70 (24%) patients at stage III were converted into stage IV and 4/68 (6%) at stage II were upstaged to IV. In the postoperative setting, PET/CT upstaged the disease in both stage IIIC and stage IV in 14/126 (11%) cases. At the end of follow-up, 28/271 (10%) patients died from BC and 40 (15%) had a recurrence of disease. On Kaplan-Meier analysis, patients with a positive PET/CT other than the primary tumor site showed both a worse overall survival and a worse disease-free survival compared with their counterpart (76 vs. 92%; P=0.063 and 65 vs. 100%; P<0.001). Conversely, in the postoperative setting, no differences in overall survival and disease-free survival were found between patients with positive and negative PET/CT findings (both P>0.05). On multivariate Cox-regression analysis, a positive PET/CT was a significant predictive factor of a poor prognosis in the preoperative setting. The significance was lost in the postoperative setting.
Conclusion: In the preoperative setting, PET/CT can provide additional diagnostic and prognostic information. Conversely, in the postoperative setting, PET/CT adds diagnostic information, but does not provide any adjunctive prognostic assessment.