[PSA:alpha 1-antichymotrypsin ratio/total PSA in the diagnosis of prostatic cancer in the range of total PSA from 4 to 10 ng/ml].
OBJECTIVE
To evaluate the usefulness of the ratio PSA:alpha-1-antichymotrypsin/total PSA (C/T) in the diagnosis of prostate cancer in the range of total PSA between 4 and 10 ng/mL.


METHODS
By using home-made ELISAs we have determined plasmatic concentrations of total PSA and complex PSA:alpha-1-ACT in 300 patients with total PSA between 4-10 ng/mL. All samples were obtained before any manipulation that could interfere the PSA levels.


RESULTS
By prostatic biopsy 85 patients (28.3%) were diagnosed of prostate cancer (CaP) and 215 (71.6%) of benign prostatic hyperplasia (BPH). The mean values of the complex PSA:alpha-1-ACT (4.2 ng/mL in the BPH patients vs 5.0 ng/mL in the CaP patients) and of the C/T ratio (0.70 vs 0.82, respectively) showed significant differences between both groups (p = < 0.0001). The total PSA did not show differences (6.1 ng/mL vs 6.0 ng/mL; p = 0.79). From all three parameter evaluated, the ratio C/T had the biggest area under the ROC (0.884) and statistically significant differences in comparison with total PSA (0.490; p = < 0.001) and the complex PSA:alpha-1-ACT (0.696: p = < 0.001). Therefore, by using a ratio C/T > 0.62 to decide the performance of a biopsy, 27% of the patients with BPH could have avoided this procedure with a 100% sensitivity. Increasing the ratio to 0.68 the specificity is 47% and the sensitivity is 95.2%. Rectal examination did not have influence on the cut-off, sensitivity, specificity and area under the ROC of the ratio C/T.


CONCLUSIONS
Our results confirm that the ratio C/T improve the diagnostic capacity of the total PSA between 4-10 ng/ml. Moreover, the rectal examination does not influence the selection of ratio C/T cut-off suggestives of CaP neither the diagnostic efficacy.
Martínez Sarmiento
M
M
Servicio de Urología, Hospital Universitario La Fe, Valencia.
España
F
F
Royo
M
M
Estellés
A
A
Aznar
J
J
Vera Donoso
C D
CD
Medina
P
P
Jiménez Cruz
J F
JF
D000368:Aged; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000175:diagnosis*; D000514:alpha 1-Antichymotrypsin / Q000097:blood*
D000514:alpha 1-Antichymotrypsin; D017430:Prostate-Specific Antigen