Genomic analysis of prostate cancer suggests best plan after surgery
Mapping the future for cancer research: TCGA project
A genomic tool can help doctors and patients make a more informed decision on the need for radiation therapy after surgery for prostate cancer.
"We are moving away from treating everyone the same," said first author Robert Den, MD, Assistant Professor of Radiation Oncology and Cancer Biology at Thomas Jefferson University, in Philadelphia, Pennsylvania. "Genomic tools are letting us gauge which cancers are more aggressive and should be treated earlier with radiation, and which ones are unlikely to benefit from additional therapy."
Although surgery for prostate cancer is meant to be curative, in some men, the cancer can regrow. Doctors have developed high risk criteria based on clinical factors, but these criteria are imperfect predictors of cancer returning, or recurrence. Only about 50% of high risk patients ever go on to develop metastases, raising the question of whether those who receive additional therapy are being overtreated.
In an attempt to better understand how to treat their patient population, researchers led by Robert B. Den, MD, and Adam Dicker, MD, PhD, Chairman of the Department of Radiation Oncology at Jefferson, together with other members of the Kimmel Cancer Center Genitourinary team assessed whether a genomic test designed to predict prostate cancer metastasis could also predict which patients would most benefit from radiation treatment after surgery. Their findings were published in the International Journal of Radiation*Oncology*Biology*Physics (2014; doi:10.1016/j.ijrobp.2014.04.052).
The test, called Decipher, from the genome diagnostics company GenomeDx, generates a gene signature from a patient's cancer tissue sample. Based on this signature, the test stratifies patients into high, intermediate, and low risk categories for cancer recurrence and metastases.
The researchers tested the genomes from tumor samples of 139 patients who had received radiation therapy following prostate surgery at Jefferson. Using medical records, the researchers grouped the patients by the treatments they received after surgery, and matched their records to the results of the genomic analysis.
The genomic analysis correctly predicted outcomes. The patients with a high Decipher score were more likely to develop metastases than those with a low score. In addition, those with a high Decipher score who received radiation earlier had longer survival than those who did not receive radiation immediately after surgery. The results showed that patients treated with radiation after surgery maintained low PSA levels for twice as long than those who were not treated with radiation.
"Our analysis suggests that genomic analysis scores could be used, in concert with other diagnostic measures such as PSA testing, to help determine which patients would benefit from additional radiation therapy and more aggressive measures, and which are less likely to benefit," said Den.The study was supported by GenomeDx, and three of its authors are employees of GenomeDx.