New findings will help to identify those who need earlier prostate cancer screening.
The study was conducted at Case Western Reserve University School of Medicine in Cleveland, OH, and the results are now published Nature Genetics.
Cancer epidemiology researcher Frederick R. Schumacher, Ph.D., led an international team comprising over 100 researchers.
These genetic markers might make it easier to determine the necessity, as well as the rate, of regular prostate cancer screenings.
Genetic markers — also known as single nucleotide polymorphisms (SNPs) — are detected at the DNA level. These are not only linked with prostate cancer, but they can also serve as a signal to doctors that someone could have a greater risk of developing any number of specific diseases.
Before this study, around 100 SNPs had been identified that could be linked with a raised prostate cancer risk. These recent findings increase the known prostate cancer genetic markers by more than 50 percent.
Schumacher and colleagues examined the DNA sequences of around 140,000 men of European descent, including data from previous studies. Around 80,000 of these men had prostate cancer, while the other 60,000 had no evidence of the disease.
With these data, they were able to identify 63 new genetic markers in those with prostate cancer — markers that did not appear in the DNA of men without the disease.
"Our findings will allow us to identify which men should have early and regular PSA screenings and these findings may eventually inform treatment decisions," says Schumacher.
He also notes that this "genetic score" might be an important factor that doctors consider when approaching prostate cancer treatment, as well.
The researchers say that there are between 500 and 1,000 genetic markers that could be linked with prostate cancer. Schumacher notes that they do not need to map them all, though.
He estimates that they only need to know around 10–20 percent to make recommendations for screening guidelines.
Prostate cancer and screening
Prostate cancer is "the most common cancer" among men, say the National Cancer Institute (NCI), and it is also "the second leading cause of cancer death" in men in the United States.
The American Cancer Society (ACS) report that prostate cancer risk goes up with age, as around 6 out of every 10 cases "are found in men older than 65." It is also more common in people with a family history of the disease, especially if a brother or father has experienced it.
A prostate-specific antigen (PSA) screening test, designed to measure the amount of this protein in blood, can help to detect the possibility of prostate cancer. The PSA level is often raised in men with prostate cancer and will prompt further testing (and treatment) if needed.
The ACS currently have a few different recommendations for prostate cancer screening. First, they suggest that men talk with their healthcare provider about the risks and potential benefits of a PSA test.
For those who choose to have the screening and no prostate cancer is found, they say that those who have a PSA of under 2.5 nanograms per milliliter may not need to be retested for 2 years. Those who test at 2.5 nanograms per milliliter or higher should be rescreened annually.
Future work and next steps
As well as investigating which genetic variants are most likely to predict increased risk (work that Schumacher and colleagues are currently focused on), researchers are also looking at genetic changes in men of different races, including African Americans and those of Asian descent.
While there is more work still to come, these results are promising, as assessing prostate cancer risk is important to many men, as well as their friends and families.
Though this study was limited as it only looked at men of European descent, it looks as though further research into other backgrounds is already under way.