Aims Despite being one of the major pathways for the spread of malignant tumours, perineural invasion (PNI) has not conclusively been shown to have an independent prognostic value for prostate cancer. Prostatic biopsy constitutes the major pathology workload in prostate cancer and is the foundation for primary treatment decisions and for this reason we aimed to estimate the prognostic value of PNI in biopsies.
Methods We followed 918 men who underwent radical prostatectomy (RP) from the prospective and population based STHLM3 study until biochemical recurrence with a median follow-up of 4.1 years. To strengthen the evidence, we combined the estimates from the largest studies targeting the prognostic value of PNI in the biopsy. We also estimated the OR of advanced stage as radical prostatectomy for PNI positive and negative men.
Results The estimated prognostic value based on our data suggested an approximately 50% increased risk of biochemical recurrence if PNI was present in the biopsy (p=0.06). Even though not statistically significant on the 5% level, this estimate is consistent with similar studies, and by combining the estimates there is in fact strong evidence in support of an independent prognostic value of PNI in the biopsy (p<0.0001). There was also an independent increased risk of advanced stage at RP for positive men (OR 1.85, p=0.005).
Conclusions The evidence supporting a clinically relevant and independent prognostic value of PNI is strong enough to be considered for pathology reporting guidelines.
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Handling editor Runjan Chetty.
Contributors PS designed the study, performed the statistical analysis and drafted the manuscript. ME and HG collected data. ME supervised the study. LE assessed the biopsies, participated in the study design and participated in the drafting of the manuscript. BD and HS provided pathology expertise. TN provided urological expertise. All authors contributed in the interpretation of the study and critically reviewed the manuscript.
Funding The study was financed by Swedish Research Council, Swedish Cancer Society and Swedish Research Council for Health Working Life and Welfare (FORTE).
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request. The complete code for this project is freely available at https://github.com/PeterStrom/PNI_clinical and data for reproducing the analyses are available upon request.
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