Deoxyribonucleic acid ploidy and serum prostate specific antigen predict outcome following salvage prostatectomy for radiation refractory prostate cancer.

PURPOSE

We assessed clinical and pathological variables for the ability to predict improved outcome following salvage prostatectomy for radiation refractory prostate cancer. We identify factors that might assist in selection of candidates for this procedure.

MATERIALS AND METHODS

Between 1966 and 1996, 108 patients (mean age 64.7 years) underwent salvage radical retropubic prostatectomy for radiation refractory prostate cancer. Preoperative serum prostate specific antigen (PSA), available in 70 patients treated since 1987, was less than 4 in 19, 4 to 10 in 31 and greater than 10 ng./ml. in 20. Serum PSA before radiotherapy was available in 37 patients. Serum PSA before radiotherapy and salvage surgery, tumor grade, deoxyribonucleic acid (DNA) ploidy and margin status were analyzed for the ability to predict cancer specific and progression-free survival (local, systemic and PSA 0.2 ng./ml. or greater). Complication rates were compared between early (before 1990) and late (1990 to 1996) salvage prostatectomy groups.

RESULTS

Overall cancer specific and progression-free survival at 10 years was 70 and 44%, respectively. The pathological stage was pT2N0 in 39%, pT3-4N0 in 42% and pTxN+ in 19% of cases. DNA ploidy was predominately nondiploid, that is diploid in 25%, tetraploid in 64% and aneuploid in 11% of tumors. Although preoperative serum PSA was not predictive of pathological stage, patients with preoperative PSA less than 10 ng./ml. had better progression-free survival than those with higher levels (p = 0.05). DNA ploidy was the strongest predictor of cancer specific (p = 0.002) and progression-free (p = 0.002) survival. Controlling for grade and PSA using the Cox proportional hazards model, DNA ploidy remained a significant predictor of prostate cancer death (p <0.001) and disease progression (p <0.001). Complication rates improved somewhat in more recently treated patients but incontinence and bladder neck contracture rates remained significant.

CONCLUSIONS

DNA ploidy and preoperative serum PSA appear to be the most important predictors of outcome following salvage prostatectomy for radiation refractory prostate cancer. Preoperative consideration of these factors may be helpful in selecting candidates for this procedure.