Table 1.
Description of 24 discrepant test results
| No. | Tumour cell% | Sequence 1 | Assay 1 | Sequence 2 | Assay 2 | Sequence new DNA | Final interpretation | Test | Explanation |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 80 | c.35_36delinsAG | wt | c.35_36delinsAG | wt | c.35_36delinsAG | c.35_36delinsAG | FNA | not targeted by assay |
| 2 | 80 | c.38_39delinsAG | wt | c.38_39delinsAG | wt | c.38_39delinsAG | FNA | not targeted by assay | |
| 3 | 90 | [c.38G>A; 40G>A] | wt | [c.38G>A; 40G>A] | wt | [c.38G>A; 40G>A] | [c.38G>A; 40G>A] | FNA | not targeted by assay |
| 4 | 80 | c.35G>A | wt | c.35G>A | wt | wt | wt | FPS | |
| 5 | 60 | c.34G>T | wt | c.34G>T | c.34G>T | c.34G>T* | c.34G>T | FNA | |
| 6 | 50 | c.35G>A | wt | c.35G>A | c.35G>A | c.35G>A* | c.35G>A | FNA | |
| 7 | 70 | c.38G>A | wt | c.38G>A | c.38G>A | c.38G>A | c.38G>A | FNA | |
| 8 | 80 | c.37G>T | c.35G>T | c.37G>T | wt | c.37G>T | FNA | not targeted by assay | |
| 9 | 70 | wt | c.35G>T | wt | c.35G>T | wt/ c.35G>T# | c.35G>T | FNS | heterogeneity |
| 10 | 20 | wt | c.34G>C | wt | c.34G>C | c.34G>C | FNS | low tumour cell% | |
| 11 | 20 | wt | c.35G>A | wt | c.35G>A | c.35G>A** | c.35G>A | FNS | low tumour cell% |
| 12 | 10 | wt | c.35G>A | wt | c.35G>A | c.35G>A* | c.35G>A | FNS | low tumour cell% |
| 13 | 20 | wt | c.35G>T | wt | c.35G>T | c.35G>T | FNS | low tumour cell% | |
| 14 | 10 | wt | c.35G>T | wt | wt | c.35G>T** | c.35G>T | FNS | low tumour cell% |
| 15 | 80 | wt | c.35G>A | wt | c.35G>A | wt | wt | FPA | high δ Ct |
| 16 | 50 | wt | c.35G>A | wt | wt | wt | FPA | high δ Ct | |
| 17 | 80 | wt | c.38G>A | wt | c.38G>A | wt | wt | FPA | high δ Ct |
| 18 | 30 | wt | c.38G>A | wt | wt | wt | wt | FPA | high δ Ct |
| 19 | 50 | wt | c.34G>T | wt | wt | wt% | wt | FPA | . |
| 20 | 50 | wt | c.38G>A | wt | wt | wt% | wt | FPA | |
| 21 | 80 | wt | c.34G>T | c.34G>T | c.34G>T | c.34G>T | FNS | ||
| 22 | 50 | wt | c.35G>A | c.35G>A | c.35G>A | c.35G>A | c.35G>A | FNS | |
| 23 | 50 | wt | c.35G>T | c.35G>T | c.35G>T | c.35G>T | c.35G>T | FNS | |
| 24 | 10 | wt | c.38G>A | wt | c.38G>A | Inconclusive | low tumour cell% and high δ Ct |
For the second DNA isolation tissue was derived from a different cube of the same tumour.
*For the second DNA isolation tissue derived from metastatic tissue was used with a higher tumour cell percentage.
DNA isolated from two different regions of the tumour showed wild-type with sequencing and with the assay wild-type in one sample and a c.35G>T mutation in another sample indicating intratumoral heterogeneity.
In the newly isolated DNA the real-time PCR based assay also showed wild-type KRAS.
wt 5 wild-type.
FNA 5 false negative result assay.
FPS 5 false positive result sequencing.
FNS 5 false negative result sequencing.
FPA 5 false positive result assay.
Bold figures indicate difference in significance vs other columns.