New DNA test could lead to better detection, fewer biopsies
TORONTO, Nov. 18, 2015 /CNW/ - If you're a man aged 50 or older, chances are your doctor has talked to you about prostate cancer. You likely know that a blood test can be used to detect raised levels of prostate specific antigen (PSA) and that a biopsy may be ordered if your PSA level is high.
But routine screening for cancer using the PSA blood test is controversial, with many experts saying it's far too inaccurate and does more harm than good. Finding a better test is the aim of Dr Eleftherios Diamandis, a researcher and clinical biochemist at Mount Sinai Hospital and senior scientist at the Lunenfeld-Tanenbaum Research Institute, part of Sinai Health System, in Toronto. Thanks to a grant from the Canadian Cancer Society, he's developing an innovative DNA semen test for prostate cancer that he hopes will provide men with more certainty and less pain.
Perhaps the biggest problem with the PSA blood test is that most men with high PSA don't actually have prostate cancer (called a false positive result). A high PSA score could be caused by a variety of other factors, such as an enlarged prostate gland, an infection, recent sexual activity or even some medications. "Most men in their 60s and 70s have some kind of urological problem," says Dr Diamandis.
Doctors will usually recommend a biopsy to determine the cause of elevated PSA, but this biopsy is painful (a needle goes through the wall of the rectum and into the prostate to take samples) and can occasionally lead to serious side effects. Only about a third of men who undergo a biopsy actually have prostate cancer. Dr Diamandis and his team foresee a future where men would first be tested using existing methods, such as the PSA test. Those men with raised PSA levels would then be further screened with the semen test, to show whether the biomarkers of prostate cancer are present and zero in on who really needs an invasive biopsy. This 2-step screening process could radically cut down on the number of unnecessary biopsies by allowing men and their doctors to make more informed decisions.
Dr Diamandis is confident that his new genomic approach to prostate cancer testing will work. "We already know the 20 most frequent gene mutations in prostate cancer," says Dr Diamandis. "We predict we will be able to test a semen sample for any of these 20 gene mutations, resulting in very few false positives. This would be far superior to the PSA test." In addition, he says, a semen DNA test could cost less than current methods. Once his study is complete in 2 years, he hopes to see the semen test go to clinical trials.
"There is a significant need to identify better biomarkers to detect prostate cancers early and accurately. For Canadian men, prostate cancer is the most frequently diagnosed cancer and the third most common cause of cancer-related death," says Dr Siân Bevan, Director of Research at the Canadian Cancer Society. "We need tools to distinguish which prostate cancers require aggressive treatment and which don't."
Dr Diamandis' research has been made possible by a $200,000 Innovation Grant from the Canadian Cancer Society, generously supported by the Haladner Memorial Foundation Research Fund in memory of Gertrude Green. Last year, the Society invested $44 million in Canadian cancer research projects like Dr Diamandis'. As the 2nd largest national charitable funder of prostate cancer research in Canada, the Canadian Cancer Society is a leader in the fight against prostate cancer.
"Thanks to Canadian Cancer Society donors, we are proud to invest in excellent Canadian scientists like Dr Diamandis who could change the way we diagnose cancers, increase survival and improve quality of life," says Dr Bevan.
About the Canadian Cancer Society
The Canadian Cancer Society funds the best cancer research in Canada thanks to our generous donors and our rigorous peer-review process. We are the largest national charitable funder of cancer research in Canada, funding hundreds of researchers in universities, hospitals and research centres. For more information, visit cancer.ca or call our toll-free bilingual Cancer Information Service at 1-888-939-3333 (TTY 1-866-786-3934).
SOURCE Canadian Cancer Society (National Office)
For further information: Rosie Hales, Communications Specialist, Canadian Cancer Society, [email protected], 416-934-5338