A RETROSPECTIVE STUDY OF HIGH-MOBILITY GROUP PROTEIN I(Y) AS PROGRESSION MARKER FOR PROSTATE-CANCER DETERMINED BY IN-SITU HYBRIDIZATION

In a previous study using RNA in situ hybridisation (RISH), we found a significant correlation between high mobility group protein I/Y, [HMG -ICY)] mRNA expression and tumour stage and grade in prostate cancer p atients, suggesting that HMG-I(Y)) might be a potential prognostic mar ker in prostate cancer. However, our clinical follow-up was limited be cause cryopreserved material was used. Assessing the potential prognos tic value of this molecule is of importance because the clinical cours e of prostate cancer patients remains unpredictable. Here we describe our results on paraffin-embedded archival material from a group of 102 patients undergoing radical prostatectomy. These were evaluated for t he presence of HMG-I(Y) using RISH, and a follow-up of 12-92 months (a verage 53 months) was available. In 2 of 14 prostate cancers in which the predominant histological pattern was of Gleason grade 1-2, a high HMG-I(Y) expression was observed, whereas in 19 of 23 Gleason grade 3, and. 34 of 35 Gleason grade 4-5 tumours, high HMG-I(Y) mRNA levels we re detected (chi-square=38.78, P<0.0001). Moreover, of tumours that ex pressed high HMG-I(Y) levels, 25% were organ confined (T1-2), in contr ast to 74.5% of the invading rumours (T3, chi-square=15.8, P<0.001), F urthermore, 57% of recurrent rumours showed high HMG-I(Y) expression. However, a multivariate regression analysis including Gleason grade, c linical tumour stage, HMG-I(Y) expression and prostate-specific antige n (PSA) levels showed Gleason grade as the most accurate predictor of progression. High HMG-I(Y) levels measured by RISH were indicative of a worse prognosis, albeit that additional value over the more subjecti ve grading methods was not evident.