A prospectively designed study establishes the17-gene Oncotype DX prostate cancer test as a robust and independent predictor of the aggressiveness of prostate cancer based on a patient’s diagnostic specimen. Tumor aggressiveness, as measured by the test’s Genomic Prostate Score, was similar in African American and white men.

“This study confirms the findings of a prior clinical validation study showing [the Genomic Prostate Score] as a predictor for adverse surgical pathology, a clinically actionable endpoint. The inclusion of genes representing multiple biologic pathways contributes to the robust predictive capacity of the assay. This assay should have clinical utility in informing decision-making regarding active surveillance vs immediate treatment for men with newly diagnosed prostate cancer,” said lead author Jennifer
Cullen, PhD, MPH, Director of Epidemiology Research at the Center for Prostate Disease Research, Uniformed Services University, Rockville, Maryland.¹ The results of this study have not been presented previously, she noted.

“If this test is done on the biopsy specimen before surgery, it can help with first-line treatment decisions. It is appropriate for patients who are interested in pursuing a watch-and-wait approach to their disease, especially who appear to have clinically low-risk tumors. If the [Genomic Prostate Score] is low, it could support a decision to defer treatment. If the result is high, it indicates more aggressive disease and supports a decision in favor of immediate treatment,” she explained.

“A majority of men are in this position: Can I delay treatment for my cancer? This test helps patients and physicians decide if immediate treatment is needed,” Dr. Cullen stated.

Study Details

The study included 402 men treated with radical prostatectomy between 1999 and 2011 at two U.S. military centers: Walter Reed National Military Center and Madigan Army Center. The Genomic Prostate Score was assessed from archival fixed paraffin-embedded needle biopsy tumor tissue, and the result was correlated with biochemical recurrence after surgery and with the finding of adverse pathology at surgery.

The primary aim of the study was to determine if the Genomic Prostate Score was associated with biochemical recurrence after surgery. The study showed that the score predicted a wide range of 5-year risk of biochemical recurrence and found that 25% of patients had a risk of less than 10% for a biochemical recurrence within 5 years of radical prostatectomy.

“This study validates [the Genomic Prostate Score] as a strong and independent predictor of biochemical recurrence following radical prostatectomy within all subgroups defined by clinical and pathologic features, including race,” Dr. Cullen stated.

In univariate analysis, the score was also associated with time to metastasis, she continued. In multivariate analysis adjusted for significant clinical and pathologic factors from the univariate analysis, Genomic Prostate Score was strongly associated with adverse pathology (P < .001), including both high-grade and non–organ-confined disease, in the overall cohort and within clinical and pathologic subgroups, including race and National Comprehensive Cancer Network risk groups.

Some unique aspects of this cohort of men include a high proportion of African American men, long-term subject follow-up with high retention rates, and an equal-access health-care setting.

The Oncotype DX prostate cancer test is commercially available but not yet covered by most insurers, Dr. Cullen said. The data on biopsy specimens have not been presented previously, she noted. Genomic Health has a patient assistance program for patients interested in getting the test. ■

Disclosure: Dr. Cullen has received research funding from Genomic Health.

Reference

1. Cullen J, Rosner I, Brand T, et al: A prospectively-designed study to determine the association of a 17-gene Genomic Prostate Score with recurrence following surgery for localized prostate cancer. ESMO 2014 Congress. Abstract LBA22. Presented September 28, 2014.