Validation of LRG1 as a potential biomarker for detection of epithelial ovarian cancer by a blinded study

Abstract

Background: Leucine-rich alpha-2-glycoprotein (LRG1) was found to be differentially expressed in sera from patients with Epithelial Ovarian Cancer (EOC). The aim of this study is to investigate the performance of LRG1 for detection of EOC, including early stage EOC, and to evaluate if LRG1 can complement CA125 in order to improve EOC detection using two independent blinded sample sets.

Methods and results: Serum LRG1 and CA125 were measured by immunoassays. All assays were performed blinded to clinical data. Using the two independent sample sets (156 participants for sample set 1, and 233 for sample set 2), LRG1 was differentially expressed in EOC cases as compared to healthy, surgical, and benign controls, and its performance was not affected by the conditions of blood collection. The areas under the ROC curve (AUC) for LRG1 in differentiating EOC cases from non-cases were 0.797 and 0.786 for sample set 1 and 2. For differentiating EOC cases from healthy controls, the AUC values for LRG1 were 0.792 and 0.794. At a fixed specificity of 95%, LRG1 detects 52%, and 53.5% of EOC cases from healthy controls for sample set 1 and 2. When combining LRG1 and CA125, the AUC value increased to 0.927, which was improved compared to CA125 (AUC=0.916) (p=0.008) alone in distinguishing EOC cases from non-cases. More importantly, LRG1 also showed potential performance in differentiating early stage EOC from non-cases with an AUC of 0.715 for sample set 1, and 0.690 for sample set 2. The combination of LRG1 and CA125 resulted in an AUC of 0.838, which outperforms CA125 (AUC=0.785) (p=0.018) in detecting early stage EOC cases from non-cases using the larger sample set.

Conclusions: LRG1 could be a useful biomarker alone or in combination with CA125 for the diagnosis of ovarian cancer.

Fig 1. Serum marker levels for sample set 1.

(a) The levels of CA125, and LRG1 were examined in the serum from healthy controls, surgical controls, benign diseases, stage I/II EOC, and stage III /IV EOC. *p<0.05 indicates a significant difference between pairwise comparisons (all cases vs. all controls; early stage cases vs. all controls; late stage cases vs. all controls). (b) Marker distributions for the EOC patients from sample set 1 with different histological subtypes.

Fig 2. Serum marker levels for sample set 2.

(a) The protein level changes of CA125 and LRG1 were confirmed in the larger sample set 2. (b) Marker distributions for the EOC patients with different histological subtypes.

Fig 3. ROC curves comparing marker concentrations in cases to non-cases for sample set 1.

(a) ROC analyses for CA125 and LRG1 to differentiate EOC from non-cases. (b) ROC analyses for CA125 and LRG1 to differentiate early stage EOC from non-cases.

Fig 4. ROC curves comparing marker concentrations in cases to healthy controls for sample set 1.

(a) ROC analyses for CA125 and LRG1 to differentiate EOC from healthy controls. (b) ROC analyses for CA125 and LRG1 to differentiate early stage EOC from healthy controls.

Fig 5. Multimarker panel analysis.

The performance of multimarker panels in distinguishing EOC/ early stage EOC from non-cases using sample set 1and sample set 2.