Table 5.
Key features of the protocols for comparison
| Feature | PathVysion | PharmDx | INFORM | CISH |
| Reagents | Preparation required | Ready to use | Ready to use | Ready to use |
| Stability of reagents | pH requires checking | OK | OK | OK |
| DAPI | Bright | Low intensity | Not provided | - |
| Background | Orange fluorescence | Strong; green fluorescence | Faint; green fluorescence | - |
| Stability of signal | Good | Rapid quenching of FITC signal | Good | Excellent |
| HER2 probe | Spectrum Orange; clear signal but high background fluorescence | Texas red; strong clear signal | FITC; strong clear signal | Chromogenic; peroxidase-based immunodetection, clear signal |
| CEP17 probe | FITC; very strong signal, with blurring of large signals | FITC; faint and transient | - | - |
| Tissue morphology | Poor definition; control with H&E to view areas of interest | Very poor definition; control with H&E to view areas of interest | Poor definition; control with H&E to view areas of interest | Good definition, allowing simultaneous analysis of amplification and histopathology |
| Microscope | Fluorescent | Fluorescent | Fluorescent | Normal light |
| Storage | 1 year at -20°C | 1 year at -20°C | 1 year at -20°C | Long period at ambient temperature |
| Threshold | OK | OK | CISH threshold must be applied and borderline cases must be evaluated with a dual-probe method (5–10) |
DAPI, 4,6-diamidino-2-phenylindole; HER2, human epidermal growth factor receptor 2; CEP17, chromosome enumeration probe 17; FITC, fluorescein isothiocyanate; H&E, haematoxylin and eosin staining; CISH, chromogenic in situ hybridisation.