New test better personalizes treatment for prostate cancer

Toronto, ON – Researchers at the Ontario Institute for Cancer Research (OICR) and University Health Network (UHN), have identified a new DNA-based test that could be used to better predict how prostate cancer patients will respond to treatment and to prevent relapse. The study was co-led by Dr. Rob Bristow, a clinician-scientist at Princess Margaret Cancer Centre and Dr. Paul Boutros, a principal investigator at OICR. Their findings were published online November 13 in the journal The Lancet Oncology.

“Prostate cancer is the most common cancer among Canadian men and is diagnosed in one of seven Canadian men. Current tools used to determine the optimal treatment for individual patients are imprecise,” said Dr. Tom Hudson, president and scientific director of OICR. “This test is a promising new tool that will generate more accurate information about how tumours will respond to treatment and provide more targeted treatment options for patients.”

Between 30 and 50 percent of prostate cancer patients treated with image-guided radiotherapy or radical prostatectomy (removal of the prostate) see their cancer recur. These patients require more aggressive treatment such as chemotherapy or hormone therapy. By identifying these patients at the outset and treating them more aggressively from day one, clinicians hope to prevent relapse. Patients who were not likely to relapse would also be spared these systemic treatments and their side effects.

The test is a simple biopsy performed in patients before treatment occurs. The biopsy is analyzed for two characteristics: genes identified with prostate cancer that may have been activated, and the oxygen content of the tissue. The study has shown that with these characteristics combined the recurrence of cancer can be predicted within three days with 80 percent accuracy. Emilie Lalonde, a PhD student co-supervised by Drs. Bristow and Boutros, and first-author of the study, notes “This is the first time the genomics and oxygen-content have been linked together to predict patient outcomes.”

“This is the first test of its kind that doesn’t require surgery to decide if additional therapy is required,” said Dr. Boutros. “From a patient perspective all that is needed is a biopsy. The information provided by this test could be given to the patient to make a better decision about his own health. There is currently a real dilemma in identifying the men who would benefit from aggressive treatment and those men who would not – this test will provide much more accurate information and allows for improved treatment decisions.”

The test is now undergoing additional validation studies which will be conducted over the next few years. Researchers estimate that it could be in the clinic within two to five years.

Funding for the study was provided by Prostate Cancer Canada, the Movember Foundation, OICR and the Princess Margaret Cancer Foundation, with assistance from the Wellcome Trust Clinical Research Facility, Addenbrooke’s Clinical Research Centre.