Age adjustment may be delaying detection of prostate cancers in senior men (9/24/2007)

Age adjustment, a method used by physicians to evaluate prostate-specific antigen (PSA) levels and cancer risk in men according to age, may be hindering the early detection of prostate cancer in older men, according to a study released Sept. 14 in the Journal of Urology.

The lead author is Amanda Reed, M.D., of The University of Texas Health Science Center at San Antonio's Department of Urology.

According to age adjustment, the PSA cutoff at which physicians recommend a prostate biopsy is based on the man's age. A physician adjusting for age may recommend a biopsy for a 50-year-old man when the man's PSA reaches 2.5 nanograms per milliliter (ng/ml), but not routinely recommend a biopsy for a 70-year-old until that man's PSA level reaches 6.5 ng/ml.

Historically, the rationale is that younger men may be at a higher risk over the long term from prostate cancer, whereas older men may have a lower risk from some slow-growing tumors.

But in her study, Dr. Reed found that the higher the PSA, the higher the risk of aggressive prostate cancer, and the older the man, the higher the risk of aggressive prostate cancer. "This is an important observation because many physicians do age adjustment," said co-author Ian M. Thompson Jr., M.D., professor and chair of the Department of Urology. "But it may be a very bad thing to do. In an older man, allowing a PSA to go high is, if you will, a 'perfect storm' of colliding risk factors. We may be delaying the diagnosis of some lethal cancers."

Dr. Reed also observed that in older African-American men, allowing PSA to rise to a higher level (such as 6.5 ng/ml in a 70-year-old) increased the risk of aggressive prostate cancer by as much as fourfold. A 55-year-old African-American man with a PSA of 2.5 ng/ml has an 8 percent risk of aggressive disease, compared to a 33 percent risk for a PSA of 6.5 ng/ml in a 70- year-old.

Drs. Thompson and Reed said a better approach is to consider all variables of a man's risk, including age, family history and PSA. A risk calculator at www.compass.fhcrc.org/edrnnci/bin/calculator/main.asp, based on data from the National Cancer Institute's Prostate Cancer Prevention Trial that ended in 2003, is an excellent tool to assess risk at all ages, they said.

Dr. Reed is a fourth-year resident in the Department of Urology.

Dr. Thompson holds the Henry B. and Edna Smith Dielmann Memorial Chair at the Health Science Center and the Glenda and Gary Woods Distinguished Chair in Genitourinary Oncology at the Cancer Therapy and Research Center (CTRC). He is director of the Genitourinary Clinic at CTRC.

Dr. Thompson is a member of the San Antonio Cancer Institute (SACI), one of the three National Cancer Institute Cancer Centers in Texas. SACI is the academic oncology partnership of the Health Science Center and CTRC.

Note: This story has been adapted from a news release issued by The University of Texas Health Science Center

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