Supersensitive PSA-analysis after radical prostatectomy: A powerful tool to reduce the time gap between surgery and evidence of biochemical failure

Background: Using three commercially available, unmodified PSA assays, 917 sera of 355 patients after radical prostatectomy underwent native and lyoph ilisation-concentrated PSA-detection to evaluate the benefit of serum conce ntration as a tool to increase sensitivity for earlier detection of recurre nt prostate cancer after RP. Materials and Methods: We evaluated Abbott IMX , Tosoh AIA-600 and DPC-Immulite Assay in the follow-up of 355 patients. Me an follow- up time is 374 days (43-2057). All sera underwent native analysi s and 4fold- lyoconcentration and subsequent triplicate standard analysis o n each assay. Evaluation of native and concentrated sera: A PSA-value of gr eater than or equal to 0,10 ng/ml was positive. Sera reading >0.10 ng/ml we re considered negative. In 4-fold concentrated sera this means a calculated increase of sensitivity to greater than or equal to 0.025 ng/ml. The avera ge day of detection of a first positive signal either in native or concentr ated sera for each assay was calculated as well as the time showing the ave rage day difference of earlier detection in the lyoconcentrated sera for ea ch assay. 20 Female sera were run and consistently read zero values in nati ve and concentrated sera. results: In 355 patients, the number of PSA-posit ive patients were 58 65 and 62 on Abbott, Tosoh and Immulite, respectively. 17/58 (29.3%), 19/65 (29.2%) and 20/62 (31.7%) patients could be identifie d earlier in lyoconcentrated than in native sera. A mean time advantage of 308-336 days was found. No patient who was positive according to supersensi tive criteria had a negative supersensitive result. in his later follow-up. 17/19 (89.4%) patients in the Tosoh, 17/20 (85%) in the Immulite and 10/17 (58.8%) in the Abbott were identified as PSA-positive within one year afte r RP. Conclusion: PSA was positive in lyoconcentrated sera a mean of one ye ar earlier than in native sera The maximum time advantage of lyoconcentrati on was 862 days, indicating PSA-recurrence 2.3 years earlier than standard analysis. 58.8-89.4% of patients with biochemical evidence of PSA-recurrenc e in supersensitive analysis were found within one year after RP. Lyoconcen tration increases PSA-signals reliably in different assays. It can be perfo rmed as a quick routine procedure.