When his doctor tells a man that his prostate-specific antigen (PSA) level is a little high, it usually causes, understandably, a lot of anxiety. Unfortunately, this often leads to a painful biopsy to find out if the patient does in fact have cancer, and a lot of the time it turns out that he doesn't.

"The current methods for screening, the PSA and digital rectal exam, are really quite poor and they actually over-predict," Kar Wassmann, CEO of Source MDx (Boulder, Colorado), told Diagnostics & Imaging Week.

Wassmann said that 1.2 million men a year undergo a biopsy as a result of these tests, which are "very painful" and are associated with some risk of complications. The biopsies also run about $2,000 apiece, he said, a cost that could have been avoided if there were a more accurate way to screen for prostate cancer.

Source MDx has developed a blood test that may provide just such a solution.

A study led by researchers at Dana-Farber Cancer Institute (Boston) suggests that the new blood test used in combination with a conventional PSA screening sharply increases the accuracy of prostate cancer diagnosis, and could eliminate tens of thousands of unnecessary prostate biopsies annually.

At the annual meeting of the American Society of Clinical Oncology (Alexandria, Virginia) in Orlando, Florida, William Oh, MD, and Robert Ross, MD, reported on Sunday that the six-gene molecular diagnostic test, when combined with a PSA test, accurately detected prostate cancer more than 90% of the time. Earlier studies suggest that the conventional PSA test is 60% to 70% accurate in detecting cancer.

Wassmann said the study results were "very well received" at the meeting. "There was a poster session that lasted four hours, a lot of senior people came and talked to Drs. Oh and Ross and myself and it's a very, very solid statistical analysis of close to 500 patients – a size of a study that gets people's interest."

According to the company, nearly two-thirds of biopsies performed do not find any cancerous cells. This high rate of false positive PSA test results underscores the need for a more accurate method for detecting prostate cancer, said Oh, who is the clinical director of the Lank Center for Genitourinary Oncology at Dana-Farber.

The two-year study involved 484 participants. The group comprised 204 men with known prostate cancer, 110 men with benign prostatic hypertrophy (BPH), and 170 healthy men in a control group. (BPH can elevate PSA levels in the blood, which often leads to a biopsy to rule out prostate cancer.) These groups were split into age-matched training and validation sets.

The researchers sought to measure the accuracy of a six-gene whole blood RNA transcript-based diagnostic test developed by Source MDx, both in terms of its ability to detect prostate cancer and its ability to identify people who don't have prostate cancer.

According to the company, Source MDx researchers developed the test after initially working with a set of 174 candidate genes whose activity was compared in the different study groups. They narrowed the pool down to just six genes that, as a group, were highly sensitive in predicting which patients had prostate cancer and which were normal.

Oh said the study found that "the six-gene model was more accurate than PSA alone at predicting cancer if you had it and no cancer if you didn't. The test's accuracy improved even more when PSA measurements were added. Combined, the two tests achieved a diagnostic accuracy of more than 90% in specificity and sensitivity and eliminated most of the false-positives yielded by the PSA test.

Based on these findings, the researchers plan to conduct a larger, multicenter clinical trial involving nearly 1,000 men to determine if the findings remain valid.

"These findings are very encouraging and suggest that this new test could spare tens of thousands of men from undergoing an unnecessary biopsy," Oh said. "However, until we can verify our findings, it is important to recognize that the PSA test, despite its limitations, is still the best test available for diagnosing prostate cancer at this time."

The study was funded in part by Source MDx and a Prostate Cancer SPORE grant at Dana-Farber/Harvard Cancer Center.

In March, Soar BioDynamics (San Francisco) released its first product – Soar Dynamic Screening – that is also aimed at helping doctors more accurately diagnose prostate cancer. According to the company, the Soar Dynamic Screening demonstrates a new approach to healthcare by providing men a detailed analysis of their prostate health based on several factors beyond the standard PSA test.