Difficult-to-diagnose prostate cancers better discovered using PSA-drug therapy combo

A union of novel drug therapies and changes in prostate specific antigen (PSA) levels over time has yielded a new method for screening prostate cancers of the most aggressive and elusive kind. 

Researchers from the NewYork-Presbyterian Hospital/Weill Cornell Medical Center performed a two-phase study with 276 male enrollees to better understand the role of PSA levels in prostate cancer detection. Each participant possessed three key qualifications — a PSA greater than 4, two or more negative biopsies under their belts and proof they had undergone a normal digital rectal examination. The results revealed that PSA is a more effective indicator of prostate cancer when reviewed alongside an additional drug therapy than when it is used by itself, which is the technique physicians currently employ.

"At a time when the value of PSA is being increasingly debated, we have shown that when used in a specific way, it can be of great value in identifying men with previously undetected prostate cancer," the study's lead investigator, Steven A. Kaplan, MD, the E. Darracott Vaughan Jr., Professor of Urology at Weill Cornell Medical College and director of the Iris Cantor Men's Health Center at NewYork-Presbyterian/Weill Cornell, said in a news release.

"We have shown that using PSA with these drugs can help us differentiate prostate cancer from benign prostate disease in patients who are difficult to diagnose," Kaplan continued. "It also demonstrates a better way to use both the PSA test and these powerful drugs."

Kaplan and his team decided to focus on the group of men who presented a “diagnostic dilemma” to physicians — those patients who churn out numerous negative biopsies despite having prostate cancer. Whereas the PSA test alone “measures multiple factors associated with prostate disease, including enlargement of the prostate and inflammation,” it does not proffer definitive grounds upon which physicians can make a solid diagnosis. Therefore, researchers opted to use two 5-alpha-reductase inhibitor drugs — finasteride and dutasteride — in conjunction with a PSA test to observe whether PSA levels remain consistently high following the shrinking of the prostate or continue to rise even after reaching its lowest point. Kaplan’s theory states if either of these instances are the case, the presence of cancer is likely.

During the first phase of the study, 97 patients were given 5 milligrams of finasteride or 0.5 milligrams of dutasteride daily. The participants’ PSA levels were monitored over the course of the ensuing 12 months — once at the 6 month marker, and a second time at the culmination of the study period. At one year, a transrectal ultrasonography and a biopsy were also performed. Findings confirmed that a year of drug therapy reduced PSA in all the men by an average of 48 percent, but the reduction magnitude proved to be considerably less in 28 percent of the patients who had biopsies that detected cancer.

The second phase included 179 subjects who all received the same drug therapy, but only the patients with a PSA alteration of 0.4 ng/dl were required to undergo biopsies. Forty-two men (28 percent of the subject pool) had biopsies performed; 26 (54 percent) of those participants tested positive for cancer and of those stricken, 77 percent possessed high-grade tumors. Only those who needed biopsies received them in phase two, whereas all men in phase one went through the procedure regardless of necessity.

The precision of the Kaplan team method is substantial, saving lives, time and equipment on both sides of the examination table.

"Our study shows these drugs may be most helpful in helping us diagnose undetectable prostate cancer," Kaplan concluded.

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