Genetic test that analyzes DNA to identify men at greatest risk for developing the disease could become common clinical laboratory screen for cancer
Researchers in the UK believe a common spit test can be more accurate at determining which men are more likely to develop prostate cancer than the clinical laboratory prostate-specific antigen (PSA) blood test currently used by the National Health Service (NHS) for that diagnosis.
During a recent study, scientists at the Institute of Cancer Research, London (ICR), found that germline DNA extracted from saliva, which was then used to derive polygenic risk scores for cancer, resulted in a higher percentage of participants “found to have clinically significant disease” than the percentage that would have been identified with the use of PSA or MRI.
The salvia test works by analyzing men’s DNA to find out if they are genetically pre-disposed to developing the disease. Men who find out they are likely to develop prostate cancer can then pursue further testing and scans.
“The test assesses 130 genetic variants to provide a risk score for prostate cancer, which is the second most common cause of cancer deaths in men in the UK,” The Guardian reported.
The study found that 187 of the men in the study had prostate cancer. According to the American Cancer Society, one in eight men will be diagnosed with prostate cancer in their lifetime.
“We can identify men at risk of aggressive cancers who need further tests and spare the men who are at lower risk from unnecessary treatments,” said study leader Rosalind Eeles, PhD, of the ICR London, in The Guardian.
“With this test, it could be possible to turn the tide on prostate cancer,” Rosalind Eeles, PhD, of the Institute of Cancer Research, London, told the BBC. (Photo copyright: Prostate Cancer UK.)
Landmark Discovery
Michael Inouye, PhD, professor of systems genomics and population health at the University of Cambridge, told the BBC that researchers will look back on this study “as a landmark.” He also acknowledged that it would be a long road before widespread implementation of the test.
While some sources call the ICR’s test promising, they also acknowledge it may only have a modest effect and that there may be possible racial disparities in the findings. The study was primarily based on people with European ancestry. According to Prostate Cancer UK, black men in the UK have double the risk of developing the disease. A similar trend can be observed in the US, Statistica reported.
Dusko Ilic, PhD, professor in stem cell sciences at King’s College London, told the BBC that there was “no direct evidence” of these findings having an effect on survival or quality of life. He stressed the need for more studies to better assess the value of the test.
The salvia test is expected to be included in Prostate Cancer UK’s TRANSFORM trial, a $58 million research program partly funded by the NHS to determine the best way to screen for cancer in the UK.
Effect on Clinical Pathologists
Prostate cancer is expected to surge in the US over the next 15 years, according to UC Davis Health. Thus, pathologists should expect more men to seek ways to assess their risk. Pathologists would be wise to educate themselves fully on new and emerging tests and tools to best meet the needs of their patients.
Given the publicity generated by former President Biden’s announcement that he has an advanced case of prostate cancer, clinical laboratories should also expect more patients to request diagnostic tests that either screen for or confirm the presence of the disease.
The focus of the ongoing GenoVA study is to “determine the clinical effectiveness of polygenic risk score testing among patients at high genetic risk for at least one of six diseases measured by time-to-diagnosis of prevalent or incident disease over 24 months,” according to the National Institutes of Health.
The scientists used data obtained from 36,423 patients enrolled in the Mass General Brigham Biobank. The six diseases they researched were:
The polygenic scores were then tested among 227 healthy adult patients to determine their risk for the six diseases. The researchers found that:
11% of the patients had a high-risk score for atrial fibrillation,
7% for coronary artery disease,
8% for diabetes, and
6% for colorectal cancer.
Among the subjects used for the study:
15% of the men in the study had a high-risk score for prostate cancer, and
13% of the women in the study had a high score for breast cancer.
The researchers concluded that the implementation of PRS may help improve disease prevention and management and give doctor’s a way to assess a patient’s risk for these conditions. They published their findings in the journal Nature Medicine, titled, “Development of a Clinical Polygenic Risk Score Assay and Reporting Workflow.”
“We have shown that [medical] laboratory assay development and PRS reporting to patients and physicians are feasible … As the performance of PRS continues to improve—particularly for individuals of underrepresented ancestry groups—the implementation processes we describe can serve as generalizable models for laboratories and health systems looking to realize the potential of PRS for improved patient health,” the researchers wrote.
Using PRS in Clinical Decision Support
Polygenetic risk scores examine multiple genetic markers for risk of certain diseases. A calculation based on hundreds or thousands of these genetic markers could help doctors and patients make personalized treatment decisions, a core tenet of precision medicine.
“As a primary care physician myself, I knew that busy physicians were not going to have time to take an entire course on polygenic risk scores. Instead, we wanted to design a lab report and informational resources that succinctly told the doctor and patient what they need to know to make a decision about using a polygenic risk score result in their healthcare,” epidemiologist Jason Vassy, MD, told The Harvard Gazette. Vassy is Associate Professor, Harvard Medical School at VA Boston Healthcare System and one of the authors of the research.
“This is another great example of precision medicine,” Jason Vassy, MD (above), Adjunct Assistant Professor, General Internal Medicine at Boston University School of Medicine, told WebMD. “There’s always been a tantalizing idea that someone’s genetic makeup might help tailor preventative medicine and treatment.” Personalized clinical laboratory testing is increasingly becoming based on an individual’s genetics. (Photo copyright: Harvard Medical School.)
Increasing Diversity of Patients in Genomic Research
The team did encounter some challenges during their analysis. Because most existing genomic research was performed on persons of European descent, the risk scores are less accurate among non-European populations. The researchers for this study addressed this limitation by applying additional statistical methods to qualify accurate PRS calculations across multiple racial groups.
“Researchers must continue working to increase the diversity of patients participating in genomics research,” said Matthew Lebo, PhD, Chief Laboratory Director, Laboratory Molecular Medicine, at Mass General Brigham and one of the authors of the study. “In the meantime, we were heartened to see that we could generate and implement valid genetic scores for patients of diverse backgrounds,” he told The Harvard Gazette.
The team hopes the scores may be utilized in the future to help doctors and patients make better decisions regarding preventative care and screenings.
“It’s easy to say that everyone needs a colonoscopy at age 45,” Vassy told WebMD. “But what if you’re such a low risk that you could put it off for longer? We may get to the point where we understand risk so much that someone may not need one at all.”
Future of PRS in Clinical Decision Making
The scientists plan to enroll more than 1,000 patients in a new program and track them for two years to assess how medical professionals use PRS in clinical care. It is feasible that patients who are at high risk for certain diseases may opt for more frequent screenings or take preventative medicines to mitigate their risk.
“Getting to that point will take time,” Vassy added. “But I can see this type of information playing a role in shared decision making between doctor and patient in the near future.”
The team also established resources and educational materials to assist both doctors and patients in using the scores.
“It’s still very early days for precision prevention,” Vassy noted, “but we have shown it is feasible to overcome some of the first barriers to bringing polygenic risk scores into the clinic.”
More research and studies are needed to prove the effectiveness of using PRS tests in clinical care and determine its role in customized treatment plans based on personal genetics. Nevertheless, pathologists and medical scientists will want to follow the GenoVA study.
“It is probably most helpful to think of polygenic risk scores as a risk factor for disease, not a diagnostic test or an indication that an individual will certainly develop the disease,” Vassy said. “Most diseases have complex, multifactorial etiologies, and a high polygenic risk score is just one piece of the puzzle.”
Pathologists and clinical laboratory managers may want to stay informed as researchers in the GenoVA study tease new useful diagnostic insights from their ongoing study of the whole human genome. Meanwhile, the GenoVA team is moving forward with the 1,000-patient study with the expectation that this new knowledge may enable earlier and more accurate diagnoses of the health conditions that were the focus of the GenoVA study.
