In what may be a diagnostic advance, US and Swedish researchers have linked five inherited genetic mutations to the development of a particularly aggressive and deadly form of prostate cancer.
The findings could someday lead to development of an easy-to-administer blood test to screen for such mutations to help physicians assess the long-term risk faced by newly diagnosed prostate cancer patients, the researchers suggested.
"The ability to distinguish patients at elevated risk for having aggressive, life-threatening prostate cancer at the time of diagnosis could improve care for the subset of cases most likely to benefit from aggressive therapy and help avoid over-treatment of patients whose tumours are likely to remain indolent," the study team, led by Janet L. Stanford, co-director of the Fred Hutchinson Cancer Research Center's programme in prostate cancer research, reported in the online edition of Cancer Epidemiology, Biomarkers and Prevention.
At issue are longstanding concerns about unnecessary over-treatment of many prostate cancer patients who actually face a relatively low risk for fast disease progression and death. Because treatment can bring about undesirable side effects, such as sexual impotence and urinary incontinence, an effort has been under way to achieve a more personalised assessment of a patient's particular prognosis after diagnosis.
Markers and tumours
"Biomarkers that could distinguish between patients with indolent vs. more aggressive tumours are urgently needed," Stanford said. "The panel of markers we've identified provides the first validated evidence that inherited genetic variants play a role in prostate cancer progression and mortality. Ultimately these markers could be used in the clinic, along with other known predictors that are used to assess tumour aggressiveness, such as a high Gleason score, to identify men with a high-risk profile."
The authors, looking for genetic differences that could highlight risk differences, gathered blood samples from more than 1,300 prostate cancer patients living in the Seattle region. All were between the ages of 35 and 74 when diagnosed.
DNA analyses of the samples were compiled with those of nearly 2,900 Swedish prostate cancer patients.
The result: Five single-letter mutations (or SNPs) were isolated among the patients' "DNA alphabet" as having a significant bearing on prostate cancer progression in terms of affecting cell death, tumor growth, inflammation, androgen hormone levels, blood-vessel development and bone density.
Patients found to have at least four out of the five cited SNP mutations appeared to face a 50 percent higher risk for dying from their disease compared with those who carried two or fewer of the mutations.
Improved treatments for prostate cancer
William Phelps, program director of translational and pre-clinical cancer research at the American Cancer Society, said the push to develop more revealing diagnostic tools is driven by an acknowledgement that current treatment options can debilitate patients.
"If the treatments we had for prostate cancer were very tolerable or very safe you would probably treat everybody," he explained. "But the treatments we have available today are less than ideal."
"So certainly we can try to improve treatment," Phelps noted. "But at the same time we can also try to improve ways to identify patients who are more likely to progress rapidly from those likely to be very slow going, so we can reserve treatment for only those instances when it's really necessary."
If there are markers that better define the men whose cancer is most likely to progress, "that would certainly prove very useful in the current climate," he said.
For more on prostate cancer, visit the U.S. National Institutes of Health.
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