Phi:

FDA Approves New Blood Test to Improve Prostate Cancer Detection

Categories: Winter 2012
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Sometimes, the pearl is so obvious but, still, there’s a battle over getting it. ©photo by Cissy Lacks (from the Missouri Botanical Garden Chinese Lanterns Exhibit)

It’s been a long wait, but the FDA (U.S. Food and Drug Administration) has announced approval for Phi* (Prostate Health Index), a simple, non-invasive blood test that is 2.5 times more specific in detecting prostate cancer than PSA in patients with PSA values in the 4-10ng/mL range.

The test is not yet available but will be soon. At present, it is not covered by insurance but Beckman Coulter, developer of the test, hopes it will be covered once a billing code is assigned. In addition, Phi is proven to reduce the number of prostate biopsies in men whose PSA might otherwise indicate a recommendation for biopsy.

Typically, U.S. physicians recommend that men with a PSA in the range of 4-10ng/mL consider a prostate biopsy; however, an elevated PSA may be due to benign conditions other than cancer, which can lead to unnecessary biopsies.

Prostate Health Index helps physicians distinguish prostate cancer from benign conditions. The results of Phi’s multi-center clinical study showed a 31 percent reduction in unnecessary biopsies.

Prostate Health Index is a better test than total PSA or Free PSA because it provides more accurate information that physicians and patients need for better decision-making.

“Now, patients and physicians wondering what to do with an elevated PSA test result in the 4-10 ng/mL range have a new, noninvasive option. This test represents an advance in the science of prostate cancer management,” Dr. Catalona said.

Dr. Catalona led the multiinstitutional clinical trial that was submitted to the FDA for Phi approval.

Phi combines three markers: ProPSA, FreePSA and total PSA to determine the probability of cancer in a patient. The Prostate Health Index is more specific than conventional PSA testing.

“Phi has fewer false positives than existing tests and is more specific for aggressive prostate cancer. Phi takes diagnostic accuracy to about 75 per cent,” Dr. Catalona said.

Also, unlike existing tests, Phi is more likely than the existing PSA test to detect a Gleason 7 or higher prostate cancer before a biopsy.

“This predictive ability for cancer aggressiveness makes it significantly superior to previous PSA testing and provides additional information for making a decision about biopsy,” Dr. Catalona said.

* Phi is calculated by the following: the pro-PSA divided by the free-PSA times the square root of the total PSA.
See previous article in QUEST, “Phi Stands for Prostate Health Index,” page 8 of Summer/Fall 2012 issue on www.drcatalona.com

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