Detection of prostate cancer by prostate-specific antigen

Toward a prostate specific antigen-based prostate cancer diagnostic assay: preparation of keyhole limpet hemocyanin-conjugated normal and transformed prostate specific antigen fragments

Prostate specific antigen (PSA) molecules secreted by cancerous and normal prostate cells differ in their N-linked glycan composition, while the peptide backbone appears to be conserved. Antibodies selectively recognizing such differentially glycosylated PSA structures could form a basis for a new diagnostic assay for prostate cancer. Twenty-amino acid PSA fragments carrying di-, tri-, and tetrabranched complex-type glycans were prepared by total synthesis and conjugated to maleimide-modified keyhole limpet hemocyanin (KLH) carrier protein through backbone Cys residues. These glycopeptide/KLH conjugates were then used for antibody generation.

Impact of biochemical failure on long-term clinical outcome after radical prostatectomy for prostate cancer in Japan

Detailed information is needed to understand the impact of biochemical failure (bF) on long-term outcome after definitive therapy for prostate cancer. In all, 223 consecutive men treated with radical retropubic prostatectomy were followed and long-term clinical outcome was investigated. Pathological examination revealed more locally advanced tumors in this study compared with the typical cohorts seen in the Western series. The Cox proportional hazards model indicates pretreatment prostate-specific antigen levels and risk group stratification to be a significant predictors for bF (P<0.05), but not for overall survival. Seminal vesicle involvement was a significant predictor of systemic progression, cancer death and overall survival (P<0.05). Positive surgical margin and bF were also found to be independent predictors of overall survival (P<0.05). In contrast to reports from Western countries, this study found a significant correlation between bF after radical prostatectomy and overall survival. This may reflect years-later detection of prostate cancer in Japan compared with Western series. Biochemical failure may ultimately be translated into decreased overall survival after sufficient follow-up.

Chemical synthesis of normal and transformed PSA glycopeptides

Chemical syntheses are reported for prostate specific antigen (PSA) N-linked glycopeptide fragments consisting of an uneicosapeptide (residues 27-47 of PSA) with di-, tri-, and tetrabranched N-acetyllactosamine-type glycans. The syntheses involve simultaneous, multiple glycosylations of the corresponding pentasaccharide acceptors prepared from a common trisaccharide precursor. Globally deprotected glycans are aminated and then aspartylated with a hexapeptide, which is then extended using native chemical ligation (NCL). The glycopeptides will be used for the generation of antibodies that may form the basis for a new prostate cancer diagnostic assay.

Mass screening of prostate cancer in Changchun City of China

OBJECTIVES

Mass screening of prostate cancer in China had not been studied until now. To clarify the incidence of prostate cancer among the population of aged men in Changchun City of China, we performed a mass screening program for prostate cancer using prostate specific antigen (PSA).

METHODS

Men aged more than 50 years were examined by PSA, with a cut-off values 4.1 ng/ml. Subjects, whose serum PSA concentration was more than 4.1 ng/ml, were recommended to secondary examination of transrectal ultrasound-guided systematic six-sextant biopsy examination (TRUS-guided biopsy).

RESULTS

Between April 1998 and December 2000, in the urban area of Changchun City 4218 men over 50 years old were screened. As 190 men were found to have elevated PSA and 116 men underwent a TRUS-guided biopsy of the prostate, of whom 29 men were found to have cancer. In all, the age-adjusted PSA positive rate was 4.80%, cancer detection rate was 0.74%. The age-adjusted cancer detection rate was 0.78%. After adjusted for secondary examination rate, the cancer detection rate reached 1.28%. The cases of stage B with limited cancer within the prostate gland, accounted for 62% of 29 cancer cases. Stage B was much more detected (accounted for 60%) in the PSA range of 4.1-10.0 ng/ml. Stage C and D were much more detected (accounted for 85.71%) in the PSA range over 10.1 ng/ml, with a significant difference by Fisher exact test (P < 0.05). A significant correlation of age-adjusted PSA positive rate and age-adjusted cancer detection rate adjusted by secondary examination rate was showed in six groups of Community and Army, Factory, Corporation, Post and Telecom Office, Government and Academy, and University and Technical School (r = 0.898, P < 0.01). Both of the age-adjusted PSA positive rate and age-adjusted cancer detect rate of "Universities and Technical Schools" were significantly higher than that of "Factories" (chi2 test P < 0.05).

CONCLUSIONS

The prevalence of prostate cancer was not so low in Chinese people as expected. For 50 years or older men, cancer detection rate was 0.74%, The age-adjusted cancer detect rate was 0.78%. Much more early stage cancer could be detected in the screening using serum PSA. For the different company the detection rate of prostate cancer varied each other among the groups. Age-adjusted cancer detection rate in "Universities and Technical Schools" were significantly higher than in "Factories", suggesting environment factor or diet might be associated with the prostate cancer.