Deletion of 18q recurrently occurs in prostate cancer. To evaluate its clinical relevance, dual labeling fluorescence in-situ hybridization (FISH) using probes for 18q21 and centromere 18 was performed on a prostate cancer tissue microarray (TMA). An 18q deletion was found in 517 of 6,881 successfully analyzed cancers (7.5%). 18q deletion was linked to unfavorable tumor phenotype. An 18q deletion was seen in 6.4% of 4,360 pT2, 8.0% of 1,559 pT3a and 11.8% of 930 pT3b-pT4 cancers (P < 0.0001). Deletions of 18q were detected in 6.9% of 1,636 Gleason ≤ 3 + 3, 6.8% of 3,804 Gleason 3 + 4, 10.1% of 1,058 Gleason 4+3, and 9.9% of 344 Gleason ≥ 4 + 4 tumors (P = 0.0013). Deletions of 18q were slightly more frequent in ERG-fusion negative (8.2%) than in ERG-fusion positive cancers (6.4%, P = 0.0063). 18q deletions were also linked to biochemical recurrence (BCR, P < 0.0001). This was independent from established pre- and postoperative prognostic factors (P ≤ 0.0004). In summary, the results of our study identify 18q deletion as an independent prognostic parameter in prostate cancer. As it is easy to measure, 18q deletion may be a suitable component for multiparametric molecular prostate cancer prognosis tests.
Keywords: 18q deletion; prognosis; prostate cancer; tissue microarray.