Prognostic analysis of invasive circulating tumor cells (iCTCs) in epithelial ovarian cancer

Circulating tumor cells (CTCs) have been introduced as a biomarker in detecting advanced epithelial ovarian cancer (EOC). The goals are to examine the prevalence of the invasive subpopulation of CTCs (iCTCs) in patients at high risk of EOC and to compare this biomarker to serum CA125.

We used a unique cell adhesion matrix (CAM)-based, functional cell enrichment and identification platform to isolate iCTCs from 129 preoperative patients. We confirmed the identity of iCTCs using positive epithelial (Epi+) markers and negative hematopoietic lineage (HL-) markers. Sensitivity and specificity of the assays were examined and iCTCs/CA125 were correlated with overall survival (OS), progression-free survival (PFS) and clinical parameters.

We found a 41.2% sensitivity, 95.1% specificity and 77.8% positive predictive value (PPV) of the iCTC assay in detecting patients with stage I and II EOC malignancy, and a 83% sensitivity and 97.3% PPV in detecting all stages of EOC malignancy. However, a positive CA125 test provided weak evidence to detect stage I and II malignancy (61.6% PPV) and all EOC (92.1% PPV), because of its 76.2% specificity. A significantly stronger concordance in OS and PFS of clinical factors (tumor stage, debulking and platinum sensitivity) was noted for elevated iCTCs than for serum CA125.

The CAM-initiated CTC enrichment/identification method enabled the detection of early stage EOC. iCTCs were better correlated with worse OS and PFS, more specific and better PPV than CA125 in detecting EOC malignancy in patients at high risk of EOC.