Bju International | October 12, 2011

H Lepor, CD Cheli, RP Thiel, SS Taneja, J Laze, DW Chan, LJ Sokoll, L Mangold, AW Partin
BJU International
DOI: 10.1111/j.1464-410X.2011.10568.x

Abstract:

Nadir Ultrasensitive PSA levels has some value for predicting BCR following RD.

AccuPSA assays lower limit of PSA quantification of <0.01 pg/ml greatly enhances sensitivity and specificity of nadir PSA to predict BCR following RP. Our pilot study shows an AccuPSA of 3 pg/ml has a sensitory and specificity of 100% and 75% respectively for predicting 5 year BCR following RP.

Objectives:

• Proof of concept study to evaluate a novel digital single molecule immunoassay (AccuPSA) which detects PSA 1000 fold more sensitive than current PSA methods.
• To determine the ability of the AccuPSA assay to predict 5-year Biochemical recurrence (BCR)-free survival following radical prostatectomy (RP).

Patients and Methods:

• 31 frozen serum specimens obtained from specimen logs maintained at New York University Langone Medical Center and the Johns Hopkins University School of Medicine on men who had undergone RP with a minimum of 5 years PSA follow up for those without evidence of BCR.
• For all cases, pre-operative and pathological information were available and a serum specimen between 3 and 6 months following RP with PSA level of <0.1 ng/mL measured by conventional PSA methods at the time of serum collection.
• Specimens were tested with the AccuPSA method.
• A Cox proportional hazard model and Kaplan Meier analysis was performed to determine whether AccuPSA predicted risk of biochemical recurrence.

Results:

• Overall, 11 out of 31 (35.5%) of men developed a BCR.
• Mean AccuPSA nadir levels were significantly different (p<0.001) between the non- recurrent group (2.27 pg/ml) versus recurrent group (46.99 pg/mL).
• Using a multivariate Cox proportional hazards model, AccuPSA nadir level was a significant predictor of BCR-free survival (p<0.01).
• Kaplan Meir analysis up to 5 years showed that 100% of men with AccuPSA nadir values <3 pg/mL did not develop a BCR, whereas 62.5% of men with values >3 pg/mL developed a BCR (p=0.00024).
• The sensitivity, specificity, PPV and NPV of the AccuPSA method was 100%, 75%, 69% and 100%, respectively.

Conclusion:

• AccuPSA assay predicts 5-year BCR-free survival following RP.
• Identifying a reliable predictor of BCR soon after RP has important implications for frequency of PSA testing, selection of candidates for adjuvant therapy, and reassuring a large subset of men they are not at risk of recurrence.
• Larger studies are needed to validate these findings.