High-grade prostatic intraepithelial neoplasia (PIN) is most likely a precursor of prostate cancer and is frequently associated with it, whereas the direct link between low-grade PIN and cancer is not established. The clinical evolution of isolated high-grade PIN has been the object of much concern because of the possibility of undiagnosed prostate cancer or the evolution of this premalignant lesion in invasive carcinoma.
High-grade PIN has been identified in approximately 4-14% of prostate needle biopsies.48-50 Evaluation pathology trends show that, of 62 537 initial prostate needle-core biopsies submitted by office-based urologists, processed at a single pathology laboratory, isolated high-grade PIN was diagnosed in 4.1% of the biopsies, a number which probably reflects the real incidence of this entity in general practice as opposed to reference centres.47 According to Zlotta et al. and Raviv et al.,51-53 analyzing 93 patients with diagnosis of isolated PIN without concurrent carcinoma, the cancer detection rate on repeat biopsy or operated specimen increased with PIN grades. In each PSA subgroup (0-4, 4.1-10, >10ng/ml) the subsequent cancer detection rate was higher for high-grade PIN than for low-grade PIN. Nearly 50% of patients with isolated high-grade PIN were found to have prostate cancer on repeat biopsy, whereas only 13% of patients with low-grade PIN did so.
Weinstein and Epstein noted that serum PSA levels were elevated in 90% of patients with high-grade PIN and cancer compared to 50% of those with PIN without associated cancer at the time of initial diagnosis, suggesting that serum PSA may be useful in distinguishing patients with PIN who will have cancer detected on repeat biopsy.54 In the study by Raviv etal.,51'52 the group of patients that later developed cancer had significantly higher PSA compared to patients without cancer on repeat biopsy. In high-grade PIN, the incidence of later cancer was 33% and 62%, respectively, when PSA was below 4ng/ml or above 10ng/ml.52 Therefore, all subgroups of patients with high-grade PIN, but especially those with elevated PSA, should undergo repeat biopsy. Low-grade PIN was associated with subsequent cancer in 42.8% of cases when PSA was above 10 ng/ml, in 10.7% when PSA was between 4 and 10 ng/ml and in none of the cases when PSA was ^4ng/ml.52 Low grade should cause no further action unless other factors, such as an elevated PSA, increase the suspicion of prostate cancer and should prompt repeat biopsies. The high detection rate of later cancer when PSA is over 10 ng/ml in low-grade PIN is similar to Cooner's report on the detection of prostate cancer without reference to PIN.53 When PSA is above 10 ng/ml and whatever PIN grade, it seems clear that the high detection rate is more a reflection of the undetected presence of cancer than of the presence of PIN.
Most experts agree that high-grade PIN is clearly a pre-neoplastic lesion because it fulfils all requirements for such a lesion. Thus, high-grade PIN, especially when associated with high PSA or abnormal DRE or TRUS, should be taken as a signal of high to extremely high probability of prostate cancer and repeat biopsies should be performed.53
• High-grade PIN in first prostate biopsy requires repeat biopsy.
Was this article helpful?