Intro & Aims
The aim of this project is to review the correlation between Clinical P16 Immunohistochemistry(IHC) staining identification and PCR HPV analysis in head and Neck cancers. Prior to the introduction of the new TNM8 staging system, to asses the accuracy of clinical identification of P16 IHC. TNM 8 which will be rolled out in January 2018 will includes HPV p16-mediated oropharyngeal carcinoma (OPC). This will be the first time that there have been separate Clinical and Pathological N-Definitions and NHC Classifications
Over a 4 Month period in Department of Pathology, all samples from the head and Neck which were stained for P16 were collected. Cases were only added for Head and Neck Morphology codes. Once theses results were obtained comparison was made between IHC P16 Staining Identification and PCR for HPV.
Correlation between P16 and HPV PCR occurred in 70% of the cases. In theses that correlated 71% occurred in when the P16 was Negative, while occurring only in 29% of those P16s which were positive. Disagreement occurred between P16 IHC and PCR HPV in 20% of cases. Of these cases 75% of the disagreement was due to equivocal results for the P16 IHC. While 25% was due to a positive P16 false positive, however a false positive rate of only 5% is within the ranges previously recorded of between 3-38%. Errors in processing occurred in two cases.
- Reinforcing Subjective nature of P15 IHC with a bias towards P16 negative samples.
- Low Rate of False Positives 5%.
- Equivocal area occurs to those samples where staining is around 60-70% of nuclear and cytoplasmic staining subjectively.
- Continued use of both P16 and HPC PCR is advocated as advised by TNM8. Further review of this would be ideal following implementation of TNM8.