Variation of serum prostate-specific antigen levels: an evaluation of year-to-year fluctuations

James A Eastham ¹, Elyn Riedel , Peter T Scardino

⁰Memorial Sloan-Kettering Cancer Center, New York, NY, USA. easthamj@mskcc.org

Jama +

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May 29, 2003

View abstract on PubMed

Summary

Prostate-specific antigen (PSA) levels fluctuate naturally year-to-year. A single elevated PSA test result may be unreliable, and repeat testing is recommended before further prostate cancer screening.

Area Of Science

Urology
Oncology
Biochemistry

Background

Serum prostate-specific antigen (PSA) testing is a common tool for early prostate cancer detection.
However, the specificity of PSA testing is limited, leading to questions about its routine use.

Purpose Of The Study

To investigate whether natural year-to-year variations in PSA levels can render a single test result unreliable.
To assess the impact of PSA fluctuations on prostate cancer screening protocols.

Main Methods

Retrospective analysis of PSA levels from 972 unscreened men over a 4-year period.
Consecutive blood samples were analyzed for total and free PSA.
Abnormal results were defined by various PSA level cutoffs, age-specific cutoffs, free-to-total ratio, and PSA velocity.

Main Results

A significant proportion of men with initially abnormal PSA levels showed normal results on subsequent tests.
For instance, 44% of men with PSA > 4 ng/mL and 55% with elevated age-specific cutoffs had normal readings at later visits.
PSA velocity exceeding 0.75 ng/mL/year also showed variability.

Conclusions

An isolated elevation in PSA level may not be indicative of cancer and requires confirmation.
Repeat PSA testing several weeks later is advised before initiating further diagnostic procedures like prostate biopsy.

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