Table 1.
Performance characteristics measured in the analytical validation of CMx CTC assay.
| Performance characteristics | Definition | Sample composition | Measured parameter | |
|---|---|---|---|---|
| 1 | Accuracy (recovery efficiency) | Percent (recovered cells/spiked-in cells) | 33 Spiked samples in 4 concentrations in medium and blood | Percent recovery efficiency |
| 2 | Linearity | Linearity plot of percent (recovered cells/spiked-in cells) | 33 Spiked samples of 2 to 189 cells in medium and blood | Regression curve in linear plot for recovered versus spiked cells |
| 3 | LOD | Limit of detection | 52 Spiked blood samples containing 2 to 281 cells | Lowest measurable and quantifiable CLC count per 2 mL blood |
| 4 | LOB and specificity | Limit of blank and rate of false-positive detection | 8 Nonspiked medium and 32 healthy control blood samples | CTC detection in nonspiked medium and blood |
| 5 | Precision (reproducibility) | Intra-assay variability (3 tests) | Spiked blood samples in 3 concentrations: high (96–181 cells), medium (12–21 cells), and low (2–11 cells) | Percent coefficient of variation of recovery efficiency for 3 concentrations (high, medium, low) in 3 test conditions |
| Inter-assay variability (3 days) | ||||
| Inter-operator variability (3 operators) |
CTC: circulating tumor cell; CLC: cancer cell line cell.