Correlation between chromosome 9p21 locus deletion and prognosis in clinically localized prostate cancer

Some studies have reported that deletions at chromosome arm 9p occur frequently and represent a critical step in carcinogenesis of some neoplasms. Our aim was to evaluate the deletion of locus 9p21 and chromosomes 3, 7 and 17 in localized prostate cancer (PC) and correlate these alterations with prognostic factors and biochemical recurrence after surgery.

We retrospectively evaluated surgical specimens from 111 patients with localized PC who underwent radical prostatectomy. Biochemical recurrence was defined as a prostate-specific antigen (PSA) >0.2 ng/mL and the mean postoperative follow-up was 123 months. The deletions were evaluated using fluorescence in situ hybridization with centromeric and locus-specific probes in a tissue microarray containing 2 samples from each patient. We correlated the occurrence of any deletion with pathological stage, Gleason score, ISUP grade group, PSA and biochemical recurrence.

We observed a loss of any probe in only 8 patients (7.2%). The most common deletion was the loss of locus 9p21, which occurred in 6.4% of cases. Deletions of chromosomes 3, 7 and 17 were observed in 2.3%, 1.2% and 1.8% patients, respectively. There was no correlation between chromosome loss and Gleason score, ISUP, PSA or stage. Biochemical recurrence occurred in 83% cases involving 9p21 deletions. Loss of 9p21 locus was significantly associated with time to recurrence (p = 0.038).

We found low rates of deletion in chromosomes 3, 7 and 17 and 9p21 locus. We observed that 9p21 locus deletion was associated with worse prognosis in localized PC treated by radical prostatectomy.