OBJECTIVE: To assess the reliability of a new measurement of prostate-specific 
antigen (PSA) using a blotting-paper assay (nanotest) compared to the standard 
PSA immunoassay.
SUBJECTS AND METHODS: The PSA level was measured in 205 men volunteers (median 
age 70 years, range 41-75) using a nanotest and a standard PSA immunoassay, 
collected at the same time; 30 microL of capillary blood placed on to a blotting 
paper were collected for the nanotest and sent by mail to the same laboratory 
for the two assays. The results were compared statistically using the Spearman 
test, the intraclass correlation coefficient and the Bland-Altman test.
RESULTS: The nanotest threshold for an abnormal PSA level was 78 pg/mL, which 
corresponded to a standard PSA value of 3 ng/mL, with a sensitivity of 100%. 
There was a significant correlation (r = 0.98, Spearman test; P < 0.001) between 
the nanotest and the standard PSA assay. The intraclass correlation coefficient 
was 0.87. The Bland-Altman test showed a good agreement between the nanotest and 
the standard PSA assay, but there was an increasing proportional difference with 
increasing PSA value.
CONCLUSION: There was a very high correlation between the nanotest and the 
standard PSA assay, especially for standard PSA levels of <5 ng/mL. Economic and 
clinical studies are indicated to confirm the utility of the nanotest in 
organized mass screening of prostate cancer.