Cancer Research Lab

The results of a single total prostate-specific antigen test, done between the ages of 44 and 50, can reliably predict prostate cancer up to 25 years later, new research shows.

Dr. Hans Lilja, from Memorial Sloan-Kettering Cancer Center in New York, and colleagues analyzed the long-term predictive power of total PSA, free PSA, and human kallikrein 2 levels measured between the ages of 44 and 50 years in 21,277 men enrolled in the Malmo (Sweden) Preventive Project between 1974 and 1986. The analysis focused on the 498 patients who developed prostate cancer during follow-up through 1999, and on 1222 matched control patients who did not.

Cancer risk was 1.0% to 7.5% for men with a total PSA of 0.5 ng/mL or lower, the investigators report in the February 1st issue of the Journal of Clinical Oncology.

At follow-up, up to 25 years later, men with a total PSA of 0.51 to 1.0 ng/mL had a 2.51-fold increase in prostate cancer risk compared with men with levels of 0.5 ng/mL or lower.

Men with total PSA levels of 2.01 to 3.00 ng/mL, which are often considered within the normal range, had a 19.1-fold increase in prostate cancer risk compared with men who had levels of 0.5 ng/mL or lower.

Free PSA and human kallikrein 2 levels in middle age were also significant predictors of prostate cancer later on, the report indicates. However, in predicting the long-term risk of prostate cancer, these measures did not provide useful information beyond that obtained with total PSA testing alone.

“The current data suggest that early biochemical changes (ie, slightly increased release of PSA and human kallikrein 2 into blood) indicate a predisposition to prostate cancer that may be detectable two decades before the disease is diagnosed clinically,” Dr. Lilja and colleagues conclude.

They caution that “recommendations to undergo biopsy on the basis of our findings would be premature, given that biopsies performed 15 to 25 years before the cancer would otherwise be diagnosed may not be informative.”

“Our data strongly suggest that we should encourage all men to get a PSA test at age 45 - 50, not to try to detect cancer, but to work out their long-term cancer risk,” Dr. Lilja said.

“We should now focus our subsequent screening efforts on the men at highest risk, spending our time and energy making sure that these men come in for regular screening (e.g. yearly) and making sure that they get the very best tests available. Men at lower risk of cancer may not require such intensive screening.”