New Evidence Supports Continued PSA Screening for Prostate Cancer

Laurie Barclay, MD

June 17, 2004

June 17, 2004 — Continued screening for prostate cancer with prostate-specific antigen (PSA) is warranted, according to the results of a study published in the June 14 issue of the Archives of Internal Medicine. A substantial proportion of consecutive patients with nonpalpable (T1c) prostate cancer diagnosed by PSA screening had clinically significant disease.

"The importance of screening for early-stage prostate cancer has been debated in the literature. However, there are well-established prognostic factors (Gleason score [GS], pretreatment PSA, and percent positive biopsy findings [%+Bx]) that predict biologically aggressive disease," write Ryan P. Smith, MD, and colleagues from the University of Pennsylvania in Philadelphia. "These factors, together with a patient's age and general state of health, will permit physicians to project the effect of a prostate tumor over the patient's expected lifetime."

From 1991 through 2002, 977 patients with T1c prostate cancer were evaluated and classified according to pretreatment PSA level, GS, %+Bx, and age.

Of the 977 patients, 601 (61.5%) were found to be at risk for clinically significant tumors. These included 130 patients classified as high risk based on tumor characteristics alone (GS = 8-10 or PSA level >20 ng/mL; or GS = 7 or PSA level >10-20 ng/mL and >50%+Bx), with a historical four-year PSA control of 10% to 30% after definitive therapy. Forty-five additional patients were classified as intermediate risk (GS = 7, PSA level >10-20 ng/mL, and 34%-50%+Bx), with a historical four-year PSA control of 50% to 60% after definitive therapy.

Based on age and GS, additional patients were identified with a cumulative anticipated prostate cancer mortality greater than 30% to 50%, including 89 patients with GS = 7 and age 70 years, and 337 patients with GS = 6 and age 65 years.

A potential study limitation is underestimation of the incidence of clinically significant disease because of the conservative definition of significant disease.

"A significant proportion of patients with nonpalpable disease diagnosed as having prostate cancer by PSA screening have clinically significant cancers," the authors write. "This supports the continued use of PSA screening."

The authors report no relevant financial interest in this article.

Arch Intern Med. 2004;164:1227-1230

Reviewed by Gary D. Vogin, MD

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