Is low-grade prostatic intraepithelial neoplasia a risk factor for cancer?

High-grade prostatic intraepithelial neoplasia (HGPIN) is generally accepted to be a precursor lesion of prostate cancer. The likely outcome of isolated low-grade PIN (LGPIN) lesions in prostate biopsies remains unclear. A follow-up study of 106 patients with LGPIN- and HGPIN lesions was performed.

In a 2-y period, 207 men were diagnosed with isolated PIN on standard systematic sextant biopsy of the prostate. In total, 104 patients had LGPIN and 103 had HGPIN. No patients had ever received androgen deprivation therapy, chemotherapy or radiation therapy. In all, 106 patients who underwent repeat second or third sextant biopsies were analysed in the study; 30% of these patients received a selenium-vitamin E supplement for at least 6 months.

In total, 43 had LGPIN and 63 HGPIN on the first biopsy. The mean age was 63.5 y (range 46-77) in the LGPIN group and 64.9 y in the HGPIN group. The mean total PSA was 6.96 ng/ml (range 0.59-34.13) in the LGPIN group and 8.44 ng/ml (range 0.59-35.3) in the HGPIN group. In the LGPIN group, 30% of the patients had cancer in at least one of the repeat biopsy cores. In the HGPIN group, 27% had cancer in at least one of the repeat biopsy cores. The mean total PSA of patients who had cancer in repeat biopsies with LGPIN was 7.84 ng/ml (range 2.92-34.13). The mean total PSA of the patients who had cancer in repeat biopsy in the HGPIN was 6.73 ng/ml (range 0.56-25). There was no significant difference in PSA and pathological stage between those patients who did and those who did not receive selenium-vitamin E supplements.

These data are intriguing since the risk of finding prostate carcinoma on repeat sextant biopsy in the LGPIN group is 30%. This is higher than commonly reported. The importance of recognising and re-biopsying HGPIN was confirmed. If chemoprevention could be shown to be effective, it might be beneficial not only in HGPIN but also in LGPIN. The possible activity of chemopreventive agents and their combination with iso-flavonoids needs further investigation.