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Researchers suggest that urologists consider PSA and PSA velocity values within a larger context when deciding whether to screen an older patient.
"We should be honest," said Vladimir Mouraviev, MD, PhD, research scientist in the division of urologic surgery at Duke University, Durham, NC. "These screening guidelines are a work in progress. PSA is an imperfect prognosticator, used alone. The physician also needs to consider family history or genetic predisposition for prostate cancer among first-tier relatives and prior biopsy data."
In research presented at the 2007 AUA annual meeting, Dr. Mouraviev, working with Leon Sun, MD, PhD, senior author Thomas J. Polascik, MD, and colleagues, used the Duke Prostate Cancer Outcomes database for the period January 1988 through December 2005 to review the records of 4,038 men over age 70 years with determinations of serum PSA and PSAV. The data represent 605 African-American men, 140 (23%) of whom had prostate cancer, and 3,433 Caucasian men, of whom 582 (16.9%) had prostate cancer. Median age was 75 years.
Not surprisingly, African-American men had higher levels of serum PSA concentrations and PSAV than the other men did, regardless of clinical evidence of cancer. Among men in the African-American subgroup, the odds of developing prostate cancer in a man with a PSA of 5.0 are 1.31 times that of a man with a PSA of 2.0 (95% confidence interval [CI]=1.21-1.41), whereas in the subgroup of Caucasian men, those odds are 1.12 (95% CI=1.09-1.15). No change was observed in Caucasian men with a 5-unit increase in PSAV levels (95% CI=.98-1.00).
"PSA remains a better screening tool for prostate cancer in older men than PSAV, especially in African-American men," Dr. Mouraviev said.
Based on the current data, he suggested that the PSA cutpoint at which specificity and sensitivity are optimal for African-American men is 4.0 ng/mL (71% specificity, 85% sensitivity) and for Caucasian men, 3.4 ng/mL (75% specificity, 72% sensitivity).
"There is an optimal tradeoff between sensitivity and specificity in these men," Dr. Mouraviev told Urology Times. "African-American men are unfortunately more susceptible to prostate cancer, especially the more aggressive form. If we [screen these men] using a lower PSA, we could pick up the cancer early."
While the research did not identify definitive PSA or PSAV values after which screening could be discontinued in older men, the data indicate that the value of PSA as a prostate cancer marker did not diminish with age. Further, PSA level appears to remain stable from the youngest men through the oldest men in the group, when measured at 3-year intervals, suggesting that the reliability of PSA as a marker for prostate cancer is consistent as men age.
As to the question of whether men over 70 should undergo PSA testing, Dr. Mouraviev said, "Be careful about drawing any conclusions about PSA use. There is also a moral issue in refusing to test these older patients.
"We have been very naïve in thinking that somehow we can discontinue screening in older men," he warned. "In terms of quality of life, some of these men are otherwise extremely healthy. We need to reconsider the traditional approach; we cannot ignore the many requirements of these patients."