Prostate cancer: is PSA velocity useful?

Racial differences in longitudinal changes in serum prostate-specific antigen levels: the Olmsted County Study and the Flint Men's Health Study

OBJECTIVE

To determine the distribution of, and racial differences in, changes in prostate-specific antigen (PSA) from a population-based sample of men.

MATERIALS AND METHODS

Data from 2 prospective cohort studies of a random sample of white men, aged 40-79 years in 1990, followed biennially through 2007, and African American men, aged 40-79 years in 1996, followed through 2000, were examined to assess the longitudinal changes in PSA concentrations. Serum PSA levels were determined at each examination for both cohorts and observations after a diagnosis of prostate cancer or treatment of benign prostatic hyperplasia were censored. The observed and estimated annual percentage of change in the serum PSA levels were examined by race.

RESULTS

At baseline, the median PSA level in the white men did not differ from the median level observed in the African American men (white men 0.9 ng/mL; African American men 0.9 ng/mL; P = .48). However, African American men had a much more rapid increase in the PSA level over time compared with the white men (median annual percent change in PSA for white men 3.6%/y, African American men 7.9%/y; P <.001).

CONCLUSION

These data suggest that African American men have more rapid rates of change in the PSA levels over time. If the difference in the rate of changes between African American and white men is an early indicator of future prostate cancer diagnosis, earlier detection in African American men could help to alleviate the racial disparities in prostate cancer diagnosis and mortality.

Early Detection of Cancer: Immunoassays for Plasma Tumor Markers

BACKGROUND: Plasma tumor biomarkers are widely used clinically for monitoring response to therapy and detecting cancer recurrence. However, only a limited number of them have been effectively used for the early detection of cancer. OBJECTIVE: To review plasma tumor markers used clinically for the early detection of cancer and to provide expert opinion about future directions. METHODS: Literature review, as well as our expert opinion, of plasma tumor markers that have been widely accepted for the early detection of cancer. RESULTS: In the United States, only prostate specific antigen (PSA), cancer antigen 125 (CA125), and alpha-fetoprotein (AFP) have been clinically used for the early detection of prostate, ovarian, and liver cancers, respectively. Both analytical and clinical issues related to the use of these three markers were discussed. CONCLUSION: Few plasma tumor markers have been used effectively for the early detection of cancer, mainly due to their limited sensitivity and/or specificity. Multiple approaches have been developed to improve the clinical performance of tumor markers for the early detection of cancer. Metrological traceability and antibody specificity are important issues to ensure comparability of immunoassays for the measurement of plasma tumor markers.