The maximum standardized uptake value of metastatic site in 18 F-FDG PET/CT predicts molecular subtypes and survival in metastatic breast cancer: An Izmir Oncology Group study.

PURPOSE

The purpose of this study was to analyse the association between the 18F-2-deoxy-2-fluorodeoxyglucose maximum standardized uptake value (SUVmax) of metastatic sites and molecular subtypes and survival in metastatic breast cancer (MBC) patients.

METHODS

Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) was performed in 176 MBC patients before any therapeutic intervention. The FDG uptakes of metastatic sites were evaluated using the SUVmax. Histopathological prognostic parameters, such as the tumor size, grade, lymph node involvement, lymphovascular invasion, estrogen (ER), progesterone receptors (PR), HER2 status and Ki67 were determined from the primary breast tumor tissue. The SUVmax of the metastatic sites was assessed in relation to the molecular subtypes and survival in univariate and multivariate analyses. Cox regression analysis was used to evaluate the associations between SUVmax measurements and overall survival (OS).

RESULTS

The mean SUVmax of 176 tumors was 8.0. Among the subtypes 49 (28.8%) were luminal A, 51 (28.9%) luminal B, 35 (19.8%) HER2-overexpressing, and 41 (23.2%) triple- negative, and the corresponding means of SUVmax were 5.6, 7.4, 11.4, 11.0, respectively. A cut-off value of ≤8.4 yielded 80% sensitivity and 57.1% specificity with an area under the receiver operating characteristics curve (AUC) of 0.731 for predicting that a tumor was of the luminal A subtype. A cut-off value of SUVmax ≥10.05 yielded 62.9% sensitivity and 67.4% specificity with an AUC of 0.648 for predicting a HER2 overexpressing subtype. A cut-off value of SUVmax ≥9.25 yielded 61% sensitivity and 64.4% specificity with an AUC of 0.660 for predicting a triple-negative subtype. The SUVmax could not effectively differentiate patients with luminal B subtype. Cox regression analysis showed that in patients with MBC, a SUVmax ≤7.55 acted as an independent negative prognostic factor for OS (hazard ratio/HR = 1.552).

CONCLUSION

The SUVmax of metastatic sites on pretreatment 18F-FDG PET/CT may be an independent prognostic factor for the diagnosis of molecular phenotypes and survival in MBC patients.