Researchers found chemical changes in blood DNA that separated people at higher and lower risk of prostate and breast cancer years before diagnosis. For prostate cancer, the signal appeared 5 to 8 years before diagnosis, according to a study published in Cell Genomics.
The study was small and early. It used stored blood from 491 people in Canada, and the researchers describe the approach as a way to estimate risk, not to diagnose cancer. No test based on this work is available to patients.
Still, the research points toward a future in which a blood draw might help decide who needs closer cancer screening and who could safely have less.
Inside the Research
The team, from Oxford Population Health, the University of Toronto and the Ontario Institute for Cancer Research, used blood samples from the Ontario Health Study collected from people who were cancer-free at the time, according to the University of Oxford. Some later developed breast or prostate cancer; others stayed cancer-free.
Of the 491 samples, 171 came from people later diagnosed with breast cancer, 93 from people later diagnosed with prostate cancer, and 227 from matched cancer-free controls, News-Medical reported. Samples were drawn from two weeks to nine years before diagnosis.
The researchers looked at methylation, chemical tags on DNA that act like switches for gene activity. They analyzed cell-free DNA, fragments released into the blood as cells die. Rather than hunting for tumor DNA itself, the method looks for patterns that may reflect the body's early response to developing cancer.
For prostate cancer, the strongest signal came from methylation changes in DNA regions called silencers, which normally help switch genes off. People the model classified as high risk had a 3.55-fold higher rate of prostate cancer diagnosis during follow-up. For breast cancer, signals came from regions called enhancers and were weaker. The high-risk group had about a 2.3-fold higher rate, and the model could distinguish higher- and lower-risk women 1.5 to 8 years before diagnosis, according to the University of Toronto's Temerty Faculty of Medicine.
Researchers Say It Could Guide Screening, Not Replace It
The authors suggested that for prostate cancer, which has no population-wide screening program in many countries, this kind of test could eventually help identify people who need closer screening while sparing low-risk people unnecessary testing. For breast cancer, the signals were weaker, and the test would be better suited to complementing existing risk tools.
"Together, these studies chart a progression from detecting established tumors to identifying the earliest systemic signals of cancer development," said Philip Awadalla, professor of molecular genetics at Oxford Population Health and the University of Oxford's Big Data Institute, Medical Xpress reported. He said the work supports a future in which minimally invasive blood tests could complement existing screening. The study was led by Nicholas Cheng, who completed his doctorate at the University of Toronto under Awadalla's supervision.
The Evidence Check
This is early-stage research. The study included a few hundred people from one Canadian cohort, so the findings may not apply to other populations, including more racially and ethnically diverse U.S. groups. The researchers checked their signals against outside datasets, but that is not the same as testing the approach in a large new group followed forward in time.
The study showed that certain DNA patterns were associated with later diagnoses. It did not show that catching those signals leads to earlier treatment, fewer deaths, or better outcomes. A higher relative risk also does not mean a person with a positive signal will get cancer, and some people flagged as low risk still did.
Current medical guidance has not changed. In the U.S., mammograms every two years starting at age 40 are recommended for women at average risk, and men ages 55 to 69 are advised to discuss PSA testing for prostate cancer with a clinician. Those decisions should not be delayed while blood-based tests remain in development.
Weighing the Findings at Home
The findings are most relevant to people unsure how often to screen, including men deciding about PSA tests and women with a family history of breast cancer. For now, the practical steps are the same as before: Know your family history, talk with a clinician about personal risk, and keep up with recommended screenings.
People should be cautious about companies marketing early cancer blood tests based on headlines, especially direct-to-consumer tests that promise certainty. Ask any seller what studies support the test, whether it has FDA approval, and what happens after a positive result.
New symptoms such as a breast lump, nipple changes, blood in the urine or semen, or trouble urinating should be checked by a clinician promptly, regardless of any test.
Blood DNA patterns flagged higher cancer risk years early in this small study, especially for prostate cancer. It is a promising research direction, but it does not change screening today. MedicalDaily will report on larger validation studies as they appear.
Key Questions Answered
What did the study find?
Chemical changes in blood DNA separated people at higher and lower risk of prostate cancer 5 to 8 years before diagnosis, and of breast cancer 1.5 to 8 years before diagnosis.
How large was the study?
It analyzed blood from 491 people in the Ontario Health Study: 171 who later developed breast cancer, 93 who later developed prostate cancer, and 227 cancer-free controls.
Can I get this blood test?
No. It is a research tool and is not available to patients.
Does this replace mammograms or PSA testing?
No. The researchers describe it as a possible way to guide screening, not replace it. Current screening recommendations have not changed.
What happens next?
Researchers need larger studies in more diverse populations, plus trials showing whether acting on these signals improves outcomes.
Published by Medicaldaily.com
