Table 3.
Factors affecting the HPV diagnostics in breast tissue.
| Factors | Commentary |
|---|---|
| Sampling | |
| Sample size | Low sample size influences the statistical power of the research [139] |
| Type of analyzed samples (FFPE tissue, fresh-frozen tissue) | Formalin-induced DNA fragmentation in FFPE samples [140] |
| Age of samples (especially in case of FFPE) | Significant degradation of DNA in 4–6 years of storage [141] |
| Contamination | Manipulation with the sample |
| Diagnostics | |
| Diagnostic techniques (ISH, PCR, NGS) | It is impossible to confirm that the positive reactions are directly from mammary cells in case of PCR method [116] |
| Designed PCR primers | Variable sensitivity and specificity [8] |
| Viral factors | |
| Viral load | Extremely low viral load causes false test negativity [73] |
| Less common types of HPV undetected by PCR, etc. | Detection methods are in most cases used for the common hrHPV types |
FFPE, formalin-fixed paraffin-embedded; ISH, in situ hybridization; PCR, polymerase chain reaction; NGS, next-generation sequencing; HPV, human papillomavirus.