Perineural Invasion Linked With Prostate Cancer Bone Metastasis

Perineural invasion (PNI) was a significant predictor of increased risk for bone metastases in men with prostate cancer who had suspicion for bone metastases after a whole-body bone scan (WBBS), according to the results of a review published in Prostate.

According to the review, clinicians currently have few factors that help to predict recurrence, prognosis or bone metastasis in men with prostate cancer. In addition to Gleason score, some research has suggested that PNI in the prostate specimen may indicate metastasis of the disease.

In this study, Seyfettin Ciftci, MD, of the Sivas Numune State Hospital, Sivas, Turkey, and colleagues reviewed data from 633 men with prostate cancer diagnosed with transrectal ultrasound guided prostate biopsy (TRUS-Bx) who underwent WBBS between 2008 and 2014. All men underwent WBBS and those whose scans returned suspicion for bone metastasis had a follow-up MRI.

“Our results showed that PNI in the TRUS-Bx specimens is the most powerful predictive histopathological feature for bone metastasis, by increasing the risk of bone metastasis 11-fold in NCCN bone scan indicated patients,” wrote the authors.

The researchers divided the men into two groups based on NCCN criteria. Group 2 (n = 371) was all asymptomatic patients, all patients with Gleason sum of 8 or greater, all clinical stage T3 or T4 patients, clinical T1 patients with tPSA > 20, and clinical T2 patients with tPSA > 10. Group 1 (n = 262) was all remaining men: those classified as bone scan not indicated.

Results of the review indicated that in Group 1 there was no significant association between PNI and bone metastasis. However, the researchers noted that there were only 12 men in Group 1 with metastatic disease.

In contrast, there was a significant relationship between PNI and bone metastasis in Group 2 (P = .001). The sensitivity and specificity of PNI for bone metastasis was 72.4% and 81.7%, respectively. The positive predictive value was 77.7%.

“PNI, Log tPSA, Gleason score, positive digital rectal exam, and clinical stage were significant covariates for the prediction of bone metastasis in univariate logistic regression (LR) analyses,” the researchers wrote. “All of these parameters except digital rectal exam also continued to be significant factors in multivariate LR analysis.”

Patients positive for PNI had an 11-fold increased risk for bone metastases compared with men who were negative for PNI.

“Although PNI is a routinely reported adverse pathological feature on prostate biopsy, only 43% of experienced surgeons stated that reporting of PNI in pathology would influence their treatment decision while 57% reported that it would not,” the researchers wrote in their discussion of the study results. “According to our results, PNI in biopsy specimens has a predictive potential on bone metastasis … we recommend that PNI in TRUS-Bx specimens should be taken into consideration by physicians during prostate cancer treatment and clinical care.”