Resumen

LOPEZ LUQUE, A. et al. Determination of free prostatic specific antigen cut point for the selection of patients in first prostate biopsy. Actas Urol Esp [online]. 2006, vol.30, n.1, pp.13-17. ISSN 0210-4806.

Objetives: Determine the cut point of free PSA rate for optimize the first prostate biopsy indication. Material and methods: Prospective trial between june 2002-september 2004, We included patients in first prostate biopsy with normal rectal digital examen, total PSA between 3-10 ng/ml and normal transrectal prostate ultrasound. We realize descriptive stadistic analisis of variables age, total PSA, prostate volume and % free PSA and analitic stadistic analisis with ROC curves of variables total PSA and % free PSA for determine as of her predicts the best one rate of prostate cancer. Results: We reclute 727 men with a mean age 62.91 years, total PSA mean 6.12 ng/ml, prostate volume mean 42.78 cc and % free PSA mean 15.22%. We had 106 prostate cancer, the prostate cancer rate in first biopsy was 14.6%; 77 cases had 1 lobe prostate cancer and 29 in 2 lobes. The most frecuent gleason was 6 (46 cases 43.4%) and the second gleason 7 (43 cases 40.6%). In the ROC curves analysis, total PSA had area under the curve 0.476 (p=0.3) and 0.611 (p=0.023) for % free PSA. The optime cut point for % free PSA in our trial was 19% (Sensibility 91.4% and Specificity 20%).The use of this cut point had allowed the saving us 138 biopsies (19.11%) with the lost one of diagnose of 10 cases of cancer of prostate. Conclusions: The use of the % free PSA is useful and allows in our region the best indication of the patients who are going to first biopsy of prostate, avoiding the accomplishment of unnecessary biopsies.

Palabras clave : Prostate cancer; Total PSA; Free PSA; ROC curve; Cut point; Tansrectal ultrasound prostate biopsy.

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