To the Editor.
—We read with great interest the article by Dr Catalona and colleagues.1 We have performed a similar study in a screening population with quite similar results.2 We used a different assay (Deltia ProStatus PSA Free/Total assay of Wallac Oy Company, Turkey, Finland) that automatically measures both free and total prostate-specific antigen (PSA) equimolarly at the same time in one sample.The most prominent conclusion from the article by Catalona et al is that percent free PSA (or free/total [F/T] ratio) increases specificity to predict positive prostate biopsies in men with prostate gland volume of 40 cm3 or more in the PSA range between 4.0 and 10.0 ng/mL at a sensitivity level of 90%. In that group, 38% of biopsies could have been avoided at the cost of 10% loss of detection, independent of the result of digital rectal examination (DRE). In the subgroup of
Bangma CH, Schröder FH. Free Serum Prostate-Specific Antigen and Screening for Prostate Cancer. JAMA. 1996;275(11):837-838. doi:10.1001/jama.1996.03530350019021