Role of FDG-PET/CT in evaluating surgical outcomes of operable breast cancer--usefulness for malignant grade of triple-negative breast cancer.

BACKGROUND: The aim of this study was to evaluate the significance of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for speculating the malignant level and prognostic value of operable breast cancers.

METHODS: Of 578 consecutive patients with primary invasive breast cancer who underwent curative surgery between 2005 and 2010, 311 patients (53.8%) who received FDG-PET/CT before initial therapy were examined.

RESULTS: Receiver operating characteristics (ROC) curve analysis showed the cutoff value of the maximum standardized uptake value (SUVmax) to predict cancer recurrence was 3.8 in all patients and 8.6 in patients with the triple-negative subtype, respectively. In all patients, 3-year DFS rates were 98.8% for patients with a tumor of SUVmax ≤ 3.8 and 91.6% for patients with a tumor of SUVmax > 3.8 (p < 0.001). High value of SUVmax was significantly associated with large tumor size (p < 0.001), lymph node metastasis (p = 0.040), high nuclear grade (p < 0.001), lymphovascular invasion (p = 0.032), negative hormone receptor status (p < 0.001), and positive HER2 status (p = 0.014). Based on the results of multivariate Cox analysis in all patients, high SUVmax (p = 0.001) and negative hormone receptor status (p = 0.005) were significantly associated with poor prognosis. In patients with triple-negative subtype, 3-year DFS rates were 90.9% for patients with a tumor of SUVmax ≤ 8.6 and 42.9% for patients with a tumor of SUVmax > 8.6 (p = 0.002), and high SUVmax was the only significant independent prognostic factor (p = 0.047).

CONCLUSION: FDG-PET/CT is useful for predicting malignant behavior and prognosis in patients with operable breast cancer, especially the triple-negative subtype.