New findings may enable stratification of patients in terms of their long-term prostate cancer risk.
ORLANDO—Premalignant phases of prostate cancer occur over long periods of time and a single PSA measurement taken at age 44-50 can help predict prostate cancer diagnosis up to 30 years subsequently, according to updated findings from a study of Swedish men.
The study looked at data from a cohort of 21,277 men who submitted blood samples for a cardiovascular study during 1974-1986. The men were aged 50 years or younger at the time. The researchers previously reported that a single PSA measurement taken at age 44-50 strongly predicted prostate cancer diagnosis up to 25 years subsequently.
The update looked at five years of additional follow-up and allowed the researchers to address three new questions: Is the previously identified relationship between PSA and prostate cancer replicated in the new cases? Is PSA measured in men at age 40 or younger a predictor of subsequent prostate cancer? Can a single PSA predict prostate cancer occurring more than 25 years later?
For the update, researchers used three different definitions of prostate cancer in separate analysis: any prostate cancer; palpable cancer (cT2 or higher at diagnosis), and advanced cancer (cT3 or higher, or metastasis, at diagnosis).
Prostate cancers diagnosed in the update occurred in men younger at the time of their baseline PSA test (median 45 vs. 47 years), with a longer delay to subsequent diagnosis (median 22 vs. 17 years). The updated study produced similar results for the newly diagnosed cases compared with those in the researchers’ original reports. Moreover, the relationship between PSA and advanced cancer appeared to be stronger.
The investigators, who presented their findings at the American Urological Association annual meeting here, concluded that premalignant phases of prostate cancer occur over long periods and the carcinogenic process is associated with increased PSA. The findings suggest the possibility that extracellular PSA may itself affect carcinogenesis.
“We can conclude from our data that PSA is highly efficient as a risk stratifier,” said investigator Hans Lilja, MD, PhD, an attending research clinical chemist in the departments of clinical laboratories, surgery, and medicine at Memorial Sloan-Kettering Cancer Center in New York.
The new findings may give clinicians a better idea of how to stratify their patients in terms of very long-term risk of prostate cancer, Dr. Lilja said. Data show men aged 50 or younger, for example, who have a low PSA (at or below the population PSA median of 0.6 ng/mL), have a low long-term risk for prostate cancer and advanced prostate cancer, he noted.
Hence, these men would have little benefit from frequent repeated PSA testing. Men with higher PSA levels, however, are likely to benefit from more frequent testing, although Dr. Lilja noted that his study’s findings need to be validated in other cohorts.