In-vitro radioimmunoassay of prostate specific antigen (PSA) for the screening and management of prostate cancer in Lebanon

Full text: Immunoassays for prostate-specific antigen (PSA) are used to detect early-stage prostate cancer, monitor disease progress, and evaluate therapeutic response. At least two forms of PSA, free PSA (F-PSA) and PSA complexed to alpha-1 anti-chymotrypsin (PSA-ACT) are detected by commercial PSA assays. The fraction of F-PSA is shown to be smaller in patients with untreated prostate cancer than in patients with benign prostate hyperplasia (BPH). Thus, combined measurements of both total and free PSA are used for a better discrimination between BPH and prostate cancer. Detection of PSA for screening of prostate cancer has been a subject of debate for many years. The reason of this debate is mainly because screening for prostate cancer is not cost-effective, as was shown by studies undertaken in Europe and United States. In Lebanon, no previous programs of screening for prostate cancer were done and so the incidence of this cancer is not known. Recently, the cancer registry in Lebanon found that lung and prostate are the highest cancers in the Lebanese men. The Lebanese association of urologists noted that 80% of men suffering from prostate cancer consult their urologists when the cancer is spread outside the prostate capsule. There is a socio-economic barrier behind this delay. We decided to undertake this study for the screening of prostate cancer in Lebanon, taking into consideration the above-mentioned facts and the experience of other countries. Volunteer men aged 45 and above, who were not visitors of a urology clinic, were selected randomly. A blood sample was withdrawn from each man, then a rectal examination was done and a questionnaire was filled. The blood serum separated was assayed for total PSA first and where abnormal or borderline, was assayed for free PSA. The percentage of free to total PSA was calculated. Men having borderline or abnormal results did undergo more investigations for the definitive diagnosis of their samples. IRMA (Immunoradiometric) technology, using coated tubes was used for both total and free PSA assays. Kits from Immunotech, France were generously purchased by the IAEA, under the Regional project RAW 6/007. A total of 4557 men were screened during the period from September 2000 to end of 2002. Of these 29 men were found to have prostate cancer. The total PSA level for these cases was between 3.2 - 73 ng/ml. 4 cases though were highly suspicious, but they still needed more investigations for the final diagnosis. Among the 29 cancer patients, 2 men died as they had extensive metastases when screening was done and 3 were detected early and are under treatment. The results obtained from our study showed that the incidence of prostate cancer is high in Lebanon. The use of radioimmunoassay technology for PSA assays in the screening for prostate cancer in the Lebanese was of great benefit. Now our priority is to increase the awareness of the population about the prostate cancer for its early detection. (author)