16-Gene Signature Predicts Prostate Cancer Relapse: Presented at AACR

A new gene expression assay appears to be a better predictor of relapse and disease-free survival than the Gleason score in patients who have undergone prostatectomy for prostate cancer, researchers report.

Tracy M. Downs, MD, assistant clinical professor of surgery, Department of Urology, University of California, San Diego, United States, presented the findings at a press conference here on April 3rd in a poster session at the 97th Annual Meeting of the American Association for Cancer Research (AACR).

"It's a real problem to stratify prostate cancer patients who have a Gleason score of 6 or 7 after surgery," Dr. Downs said during a press conference held to announce the findings. "Half of patients with these scores do well, and the other half don't, but we cannot now predict who will fall into those groups."

In an attempt to move beyond Gleason scores, Dr. Downs and colleagues profiled formalin-fixed, paraffin-embedded samples of prostate carcinoma using an oligo-probe set for 512 prioritized genes with read-out on universal fiber optic bead arrays.

Tissue samples were obtained from 74 patients, retrieved from the VA San Diego Healthcare System a median of 44 months after surgery. Samples were excluded if patients received adjuvant therapy or if there was residual cancer in the prostate after resection.

From this the researchers identified 16 genes that are predictive of relapse, said Jian-Bing Fan, PhD, director of scientific research, Illumina, Inc, San Diego, California, United States. Illumina, Inc. is developing the assay and funded the research.

The gene expression signature is based on 11 genes that correlated positively and 5 genes that correlated negatively with Gleason scores obtained from histological examination (R =.63).

"This gene expression score seems to work much better than the Gleason score," Dr. Fan said. "Using it, we were able to stratify patients into 2 very distinct groups, 1 that has a 75% chance of relapse and 1 that only has a 20% chance of relapse."

Further study to validate the assay is planned.