New test improved prostate cancer risk assessment

A new genomic screening test significantly improved the ability to predict disease aggressiveness in patients at risk for prostate cancer, according to results presented at the American Urological Association Annual Meeting.

Oncotype DX (Genomic Health), based on 17 genes that signal risk for aggressive disease, was developed to overcome tumor heterogeneity and biopsy under-sampling.

The test helps physicians and patients at risk for prostate cancer choose the most appropriate treatment based on an individualized risk assessment. It also helps guide treatment decisions using the prostate needle biopsy sample taken prior to the removal of the prostate. Therefore, patients at low risk may avoid unnecessary radical prostatectomy and radiation.

“The results of our study showed that the individual biological information from the Oncotype DX prostate cancer test tripled the number of patients who can more confidently consider active surveillance and avoid unnecessary treatment and its potential side effects,” Peter R. Carroll, MD, MPH, professor and chair of the department of urology at the University of California, San Francisco, said in a press release.

“The test also identified a smaller number of patients who, despite seemingly low-risk clinical factors, had more aggressive disease,” Carroll added. “With these new study results, I believe we may be able to significantly increase the use of active surveillance, which has been limited to some extent by the absence of a validated genomic tool to more accurately distinguish low- and high-risk disease at the time of biopsy.”

An initial development study included 441 patients. Researchers analyzed 732 candidate genes and identified 288 that were predictive of clinical recurrence. In a second development study, a needle biopsy study of 167 low- to intermediate-risk patients confirmed 81 genes were strongly associated with adverse pathology, Carroll and colleagues wrote.

“Multivariate analysis of both development studies yielded 17 genes across multiple biological pathways (three stromal response, four cellular organization, three androgen, one proliferation and five reference genes) and a [genomic prostate score] algorithm,” the researchers wrote.

Researchers then conducted a validation study that included 395 patients. After adjusting for Cancer of the Prostate Risk Assessment and other standard pretreatment factors, the genomic prostate score strongly predicted high-grade and/or pT3 disease (P<.005).

Based on the addition of the biological information generated by the test, the percentage of patients identified as having low-risk disease and being potentially eligible for surveillance increased from about 10% to 26%.

Conversely, nearly 10% of patients originally classified as having very low- or low-risk disease were found to have more aggressive disease and, therefore, were re-classified as requiring immediate treatment.

“For men with prostate cancer, the ability to more precisely defines their risk level for aggressive disease is a significant leap forward,” Howard R. Soule, PhD, executive vice president and chief science officer of the Prostate Cancer Foundation, said in a press release. “Now men can have greater confidence in their treatment plans, knowing decisions are being made based on their individual biological information.”

For more information:

Cooperberg M. Abstract #2131. Presented at: American Urological Association Annual Meeting; May 4-8, 2013; San Diego.