Utility of (18)F FDG-PET/CT for predicting prognosis of luminal-type breast cancer

Abstract

Postoperative prognosis is better for hormonal receptor-positive breast cancer than for other phenotypes; however, there are no definitive predictive factors for relapse or survival. This study aimed to evaluate the maximum standardized uptake value (SUVmax) on (18)F-fluoro-2-deoxy-glucose positron emission tomography/computed tomography (FDG-PET/CT) and clinicopathological characteristics as possible predictors of postoperative relapse-free survival (RFS) and overall survival (OS) in hormonal receptor-positive breast cancer patients. We evaluated 262 patients with Stage I-III breast cancer diagnosed as luminal type (luminal A, 166; luminal B, 96 patients) who underwent preoperative FDG-PET/CT between January 2006 and December 2011 at two institutions. The relationships among SUVmax and clinicopathological factors (age, clinical T/N stage, nuclear grade, lymph node metastasis and vascular invasion) were evaluated. A phantom study was performed to correct differences in PET/CT analysis between two institutions. The patients were divided according to the SUVmax cutoff on receiver operating characteristic (ROC) analysis for OS (≤6.0 group vs. >6.0 group, AUC = 0.742). Clinical T-factor and nuclear grade were significantly correlated with SUVmax (p < 0.0001 and p = 0.0092, respectively). In the uni- and multivariate analyses using the Cox model for relapse, SUVmax was significant (p = 0.013 and p = 0.055, respectively) among characteristics. RFS curves showed that prognosis was significantly better for the SUVmax ≤ 6.0 group than for the SUVmax > 6.0 group (p = 0.004). Similarly, SUVmax was significant for OS (p = 0.007 and p = 0.008). OS was significantly different between the SUVmax ≤ 6.0 and >6.0 groups (p < 0.001). SUVmax was useful for predicting outcomes in patients with luminal-type breast cancer.

Fig. 1

Maximum standardized uptake (SUVmax) adjusted by analyzing an experimental phantom (revised SUVmax) at two institutions. After revision, the SUVmax ratio of the two institutions was close to 1.00

Fig. 2

Receiver operator characteristic (ROC) curves of revised maximum standardized uptake (SUVmax) for overall survival in luminal-type breast cancer (n = 262). The SUVmax cutoff value for overall survival was set to 6.0 after evaluating the ROC area under the curve (0.742 with 95 % CI 0.513–0.970)

Fig. 3

Relapse-free survival (RFS) curves for prognostic factors, considering the revised maximum standardized uptake value (SUVmax) and nuclear grade. The RFS of the revised SUVmax ≤ 6.0 group was significantly better than that of the revised SUVmax > 6.0 group in the log-rank test (p = 0.004). There was no significant difference in RFS between the nuclear grades (nuclear grades I/and II versus grade III) in the log-rank test (p = 0.120)

Fig. 4

Overall survival (OS) curves for revised maximum standardized uptake value (SUVmax) and nuclear grade. The OS of the revised SUVmax ≤ 6.0 group was significantly better than that of the revised SUVmax > 6.0 group in the log-rank test (p < 0.001). There were no significant differences in OS among the nuclear grades in the log-rank test (p = 0.254)