[Circulating prostate cancer specific antigens in benign hypertrophy and localized cancer of the prostate]. / L'antigène prostatique spécifique circulant dans l'hypertrophie bénigne et le cancer localisé de la prostate.

In benign hypertrophy of the prostate (88 patients) there is a good correlation between the circulating specific prostate antigen (SPA) and the size of the prostate or of the adenoma. This correlation disappears with an adenocarcinoma where tumor volume increases (46 patients). Used as a screening test for cancer, serum levels of SPA, with a threshold value of 2.5 ng/ml, has a 91 per cent sensitivity and a 37 per cent specificity. At 15 ng/ml the sensitivity is 50 per cent and the specificity is 85 per cent. Alone, the SPA level is a poor diagnostic tool: using the low threshold (2.5 ng/ml) leads to needle biopsy in most all benign hypertrophies; with the high threshold (15-23 ng/ml), 50 per cent of the localized cancers go undetected. However, for a level greater than 15 ng/ml, SPA is an argument strongly suggesting prostate adenocarcinoma. The capacity of benign hypertrophy of the prostate to "secrete" SPA is 5 times greater than the normal peripheral prostate; the capacity of cancer is 20 times greater than that of the adenoma. Individual variability in serum levels of SPA, expressed per cm3 of prostate tissue is too great to give a precise interpretation as a function of volume.

[Circulating prostatic-specific antigen in benign hypertrophy and localized prostate cancer: can PSA be considered a screening examination for localized cancer?]. / Le PSA circulant dans l'hypertrophie bénigne et le cancer localisé de la prostate: le PSA peut-il être considéré comme un examen de dépistage du cancer localisé?

Prostate-specific antigen (PSA) is increasingly used in the diagnosis of prostatic pathology. Its usefulness in the early diagnosis of prostatic cancer is controversial. The aim of the study is to evaluate the sensitivity and specificity of PSA in a population with prostate diseases. Moreover, we wanted to know if the measure of the prostate volume may increase the sensitivity of the test. In benign prostatic hypertrophy (88 patients), a good correlation exists between circulating PSA and the prostatic volume or the volume of the adenoma. This correlation disappears in the presence of an adenocarcinoma at the profit of the tumor volume (46 patients). Used as a means of screening for cancer, the serum level of PSA with a threshold value of 2.5 ng/ml has a sensitivity of 91% and a specificity of 32%. The sensitivity is 50% and the specificity is 85% at a level of 15 ng/ml. Taken alone, the level of PSA is inadequate for diagnosis: If the lower level is chosen (2.5 ng/ml), the majority of benign prostatic hypertrophies will be the object of a biopsy. If the higher level is chosen (15-23 ng/ml), 50% of localized cancers of the prostate will escape detection. Nevertheless, a level of PSA < 15 ng/ml is an argument for a strong suspicion in favor of an adenocarcinoma of the prostate. The capacity of BPH to "secrete" serum PSA is five times greater than that of the normal peripheral prostate, and the capacity of cancer is 20 times greater than that of an adenoma. The individual variability of serum PSA per cubic centimeter of prostatic tissue is too great to allow a precise interpretation as a function of volume.