Antibody to p53 a marker for nonpalpable prostate cancer

Measuring serum p53 antibody titers along with prostate specific antigen (PSA) levels appears to be a sensitive way to identify prostate cancer in patients with negative results on a digital rectal examination (DRE), investigators in Japan report. Such an assay may therefore assist physicians in deciding when a prostate biopsy is necessary.

In the January issue of the Journal of Urology, Dr. Hiroyoshi Suzuki and colleagues note that PSA is not a prostate cancer-specific protein, and that a more sensitive and specific diagnostic test would be worthwhile. Serum p53-Abs are detectable in patients with different types of cancer, and p53 mutations prolong the half-life of its protein product.They measured PSA, prostate volume, PSA density, PSA density of the transition zone, and ratio of the free to total PSA, and used an enzyme-linked immunoabsorbent assay to measure p53-Abs in patients treated at Chiba University Hospital. Included were 50 patients with benign prostate disease and 103 patients with prostate cancer, including 40 patients with T1c stage cancer.Unlike PSA and PSA derivatives, p53-Abs levels were not related to clinical stage. However, for patients with no DRE findings, p53-Abs possessed the highest efficiency of all the measured parameters. Total PSA did not differ significantly between patients with these low-grade tumors and those with benign disease (8.54 ng/mL versus 9.89 ng/mL). The p53-Abs titers were 0.403 and 1.594 (p < 0.0001)So for example, at a specificity of 90%, p53-Abs had a specificity of 56%, compared with 36% for PSA density. Therefore, four T1c tumors would be missed and 28 of 50 unnecessary biopsies in patients with no malignancy could be avoided.'Compared with PSA parameters, the p53-Abs titer does not require ultrasonography and it is more sensitive for detecting prostate cancer inpatients who have high PSA and negative DRE,' Dr. Suzuki's team points out. Thus, 'p53-Abs might be helpful in the clinical decision to perform prostate biopsy.'(Source: J Urol 2004;171:182-186: Reuters Health: January 13, 2004: Oncolink)