3-month Prostate-specific Antigen Research Articles

The serum prostate-specific antigen level three months after radiotherapy for prostate cancer: an early indicator of response to treatment

A total of 347 patients with stages A2-C adenocarcinoma of the prostate treated with external beam radiotherapy and with pretreatment and 3-month prostate-specific antigen (PSA) levels were studied to evaluate the potential prognostic significance of the fall in PSA concentration from its baseline (PSAB) to its 3-month (PSA3) level. PSA levels fell in 333 patients (96%). With two exceptions, the patients whose PSA level did not fall had low PSAB and remained without evidence of disease. Since PSA levels fall virtually always, the fact that a fall occurs is of no prognostic value. When the magnitude of the fall relative to baseline was examined, patients with the largest falls had the worst outcomes. This paradoxical result was explained by the relationship between PSAB and PSA3. Regression analysis showed that the fall in PSA level was approximately proportional to the cube root of the baseline value. Thus, patients with high PSAB had high falls, but a high PSAB was an ovewhelming predictor for poor outcome. Hence, PSA fall relative to baseline was not a meaningful prognostic factor. The only factor of prognostic value was the absolute PSA3 value. Patients with PSA3 ≤2 ng/ml fared well at 4 years (freedom from relapse, 91%; incidence of rising PSA profile, 20%); patients with PSA3 > 2, but <-10 ng/ml had an intermediate, individually indeterminate outcome (freedom from relapse, 51%; incidence of rising PSA profile, 58%); patients with PSA3 >10 ng/ml can be said to have failed treatment (freedom from relapse, 50%; incidence of rising PSA profile, 90%). Although this analysis is based on short follow-up, it shows that the PSA value at 3 months after radiation provides a remarkably early assessment of response to treatment and the only patients who can be clearly stated to have responded well to treatment are those whose PSA level falls to ≤ 2 ng/ml. The long-term implications of 3-month PSA values await further follow-up.

Serum prostate-specific antigen in monitoring the response of carcinoma of the prostate to radiation therapy

In order to assess the value of serum prostate-specific antigen (PSA) levels in the monitoring of patients with localized prostatic carcinoma undergoing radical radiation therapy, 146 previously untreated patients were entered into this study. Sixty to 70 Gy were administered to the prostate over 8 to 9 weeks. Serum PSA levels were measured prior to radiotherapy, every 3 months during the first year and every 6 months thereafter. Median follow-up was 28 months. Pretreatment PSA values exceeded 10 ng/ml in 62% (91/146). Initial PSA values were correlated with tumor size and Gleason score. Six months after completion of radiation therapy, PSA levels decreased as compared to initial value in 88.3% of the patients. It had fallen to 10 ng/ml or less in 54 (59%) out of the 91 patients with initial abnormal PSA levels. Patients whose initial PSA exceeded 50 ng/ml attained levels of 10 ng/ml or less in only 19% of the cases (6/32). Only 3 of the 55 patients (5.5%) with both initial and 6-month PSA values less than or equal to 10 ng/ml developed metastasis. Out of the 91 patients with initial PSA values over 10 ng/ml, 54 (59.6%) had a 6-month PSA level of 10 ng/ml or less, and only 4/54 (7.4%) relapsed. By contrast, 13 of the 37 patients (35.1%) with a 6-month PSA value persistently above 10 ng/ml relapsed. The 3-year relapse-free survival is 85.1% for patients with a 6-month PSA level less than or equal to 10 ng/ml, and 50.2% for patients with persistently elevated PSA values.(ABSTRACT TRUNCATED AT 250 WORDS)