title: Prostate specific antigen levels during and after external beam radiotherapy for localized carcinoma of the prostate: predictor of therapeutic efficacy.
abstract: For 105 patients with locoregional carcinoma of the prostate, prostate specific antigen (PSA) levels were evaluated before, during and after external beam radiotherapy. The median follow-up is 17 months. In 51 patients (48.5%) initial PSA levels exceeded the maximum normal value of 20 ng/ml. Nine patients kept non-declining high levels just after radiotherapy. Only one of these is free of disease. Assuming PSA levels decrease exponentially during radiotherapy, a mean half-life of 62 days (median 54, SD 26 days) was calculated. Three out of five patients with a PSA half-life of more than 88 days relapsed as compared to a 8% (3/37) relapse rate in patients with a "normal" half-life. Prolonged PSA half-life suggests residual disease. PSA levels are expected to further decrease after radiation. Six months after irradiation persistent high PSA levels were found in 14/51 (27.5%) patients. Only four of them had no evidence of manifest disease. Important negative prognostic factors for disease control in our series were non-declining high levels of PSA, a PSA serum half-life exceeding 88 days and persistence of elevated PSA values longer than six months after treatment. In our opinion, PSA is a valuable marker in the follow-up of prostate cancer patients during and after radiotherapy.
authors.affiliation: Department of Radiation Oncology, Dr. B. Verbeeten Instituut, Tilburg, The Netherlands.
authors.forename: P
authors.initials: P
authors.lastname: Rodrigus
authors.forename: A A
authors.initials: AA
authors.lastname: van Landeghem
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000951:Antigens, Neoplasm / Q000097:blood / Q000528:radiation effects*; D014408:Biomarkers, Tumor / Q000097:blood / Q000528:radiation effects*; D006207:Half-Life; D006801:Humans; D008297:Male; D008875:Middle Aged; D010315:Particle Accelerators; D011379:Prognosis; D017430:Prostate-Specific Antigen; D011471:Prostatic Neoplasms / Q000097:blood* / Q000532:radiotherapy; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy; D012074:Remission Induction; D013997:Time Factors
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D017430:Prostate-Specific Antigen