The Decipher prostate cancer gene-expression classifier can predict patients’ risk of metastasis and prostate cancer-specific mortality (PCSM) using biopsy specimens prior to radical prostatectomy or radiotherapy plus androgen (hormonal) deprivation, according to a mixed-cohort study presented at the 2017 American Society of Clinical Oncology (ASCO) Genitourinary Cancers Symposium, held February 16–18 in Orlando, Florida.
Decipher is a 22-gene metastasis risk-predicting RNA gene expression signature designed for use after radical prostatectomy, using surgical specimens, to provide adjuvant or salvage treatment decision making. Decipher is one of several commercially-available genomic tissue tests (including Prolaris and Oncotype DX) used to help determine prostate cancer aggressiveness.
The Decipher signature includes gene markers for cell cycle proliferation, adhesion and motility, immune modulation, and androgen signaling pathways. Previous studies have evaluated the use of Decipher after radical prostatectomy. The authors of the new study sought to assess the Decipher classifier’s prognostic utility when used earlier, with biopsy specimens, in order to inform initial treatment decisions.
The team studied mortality and metastasis among 175 patients treated with radical prostatectomy at the Cleveland Clinic or Johns Hopkins or radiation plus androgen deprivation therapy (ADT) at Dana-Farber in Boston. Just over half of the patients’ cancers were deemed to be intermediate-risk, 33.7% were high-risk. Only 13% of cohort patients had low-risk prostate cancer. At a follow-up of 6 years, 32 patients had developed metastatic disease and 11 had died of prostate cancer.
The classifier scores did correlate with the risk of metastasis. According to Dr. Paul Nguyen, the lead investigator from Dana-Farber, “the 5-year distant metastasis risk by Decipher score showed that the high-risk patients had a 23.4% risk of 5-year metastasis, the intermediate-risk patients had a 9.3% risk of metastasis, and the low-risk patients had a 5% risk of metastasis at 5 years.” There was no difference in outcomes between patients treated with radical prostatectomy and those treated with radiotherapy and androgen inhibition. For low and intermediate risk patients, the Decipher score also stratifies the risk of distant metastasis and “in fact, identifies a very high-risk group for distant metastasis that developed a 33.1% risk of metastasis at 5 years,” Nguyen said.